{"title":"Thermostats \u0026 Housings","description":null,"products":[{"product_id":"sierra-18-0164-9-thermostat-housing-gasket-replaces-omc-311069-gm-3789161-4-6-cyl-marine-engines-pack-of-2","title":"Sierra Thermostat Housing Gasket 18-0164-9, Replaces Yamaha YSC-13080-00-0C, Pack of 2","description":"\u003cp\u003eThe Sierra 18-0164-9 Thermostat Housing Gasket seals the thermostat housing on Yamaha sterndrive engines, preventing coolant leaks and maintaining proper cooling system pressure. This gasket is manufactured to meet or exceed original equipment quality, giving it a reliable, leak-free seal at the thermostat housing mating surface. It is round in shape and sold in a package of 2, so you have a spare on hand or enough to service two units in one order.\u003c\/p\u003e\u003cp\u003eInstalling a fresh thermostat housing gasket during any thermostat service, cooling system inspection, or overheating diagnosis helps ensure the housing seats correctly and holds pressure. Because it is a direct cross-reference for the Yamaha YSC-13080-00-0C and GM 3789161 gaskets, it drops into place wherever those original parts are called for, without modification.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-0164-9\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePack Quantity:\u003c\/strong\u003e 2\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eShape:\u003c\/strong\u003e Round\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.01 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 808282161453\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOEM Cross Reference:\u003c\/strong\u003e YSC-13080-00-0C, GM 3789161\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\u003cli\u003eYamaha sterndrive engines\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eYSC-13080-00-0C\u003c\/li\u003e\n\u003cli\u003eGM 3789161\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat does the Sierra 18-0164-9 gasket fit?\u003c\/strong\u003e The Sierra 18-0164-9 is a thermostat housing gasket designed for Yamaha sterndrive engines, directly replacing the Yamaha YSC-13080-00-0C thermostat gasket.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-0164-9 the same as the Yamaha YSC-13080-00-0C gasket?\u003c\/strong\u003e Yes, part 18-0164-9 is a direct cross-reference for the Yamaha YSC-13080-00-0C thermostat housing gasket, so it installs in the same location without modification.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes this gasket also cross-reference to a GM part number?\u003c\/strong\u003e Yes, the 18-0164-9 thermostat housing gasket also replaces GM 3789161.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow many gaskets come in a package of 18-0164-9?\u003c\/strong\u003e Each package of the 18-0164-9 thermostat housing gasket contains 2 gaskets.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat shape is the 18-0164-9 thermostat housing gasket?\u003c\/strong\u003e The 18-0164-9 is a round gasket, matching the round mating surface of the thermostat housing it seals.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the 18-0164-9 gasket weigh?\u003c\/strong\u003e The Sierra 18-0164-9 thermostat housing gasket weighs 0.01 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-0164-9 gasket genuine OEM or aftermarket?\u003c\/strong\u003e The 18-0164-9 is a Sierra-manufactured aftermarket gasket built to meet or exceed the quality of the original Yamaha YSC-13080-00-0C and GM 3789161 gaskets it replaces.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhen should I replace the thermostat housing gasket?\u003c\/strong\u003e Replace the 18-0164-9 thermostat housing gasket any time the thermostat housing is removed for service, or if coolant leaks are found at the housing seam.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is the UPC for the Sierra 18-0164-9 gasket?\u003c\/strong\u003e The UPC for the Sierra 18-0164-9 thermostat housing gasket is 808282161453.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan I reuse the old gasket instead of buying the 18-0164-9?\u003c\/strong\u003e A new 18-0164-9 gasket is recommended rather than reusing the old one, since gaskets compress and can leak once removed from the thermostat housing.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988027093211,"sku":"SIE-18-0164-9","price":3.49,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-0164_lg__15556.1558117879.500.750.jpg?v=1785188014"},{"product_id":"sierra-18-0182-9-thermostat-gasket-replaces-evinrude-johnson-337068-pack-of-2-for-evinrude-johnson-outboards","title":"Sierra 18-0182-9 Thermostat Gasket, Pack of 2 - Fits Johnson\/Evinrude 200-235 HP Outboards","description":"\u003cp\u003eThe Sierra 18-0182-9 Thermostat Gasket is a replacement gasket for the thermostat housing on select Johnson\/Evinrude outboard motors, sold as a pack of 2 so you have a spare on hand or can service both cylinder banks in one job. The gasket seals the thermostat housing to the cylinder head, maintaining proper cooling system pressure and preventing water leakage around the thermostat during operation. It is round in shape with a multi-colored appearance and is built to meet or exceed the quality of the original equipment part it replaces.\u003c\/p\u003e\u003cp\u003eThis gasket is designed for Johnson\/Evinrude outboards rated at 200 HP (1977-83) and 235 HP (1978-85). It is also cross-referenced to several other aftermarket and OEM part numbers, making it a straightforward swap for boat owners and marine technicians sourcing a replacement gasket by an equivalent part number. Each pack ships as a lightweight, low-cost maintenance item intended to be replaced any time the thermostat housing is removed or serviced, ensuring a proper seal and preventing coolant leaks after reassembly.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-0182-9\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Type:\u003c\/strong\u003e Thermostat Gasket\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePack Quantity:\u003c\/strong\u003e 2\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eShape:\u003c\/strong\u003e Round\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eColor:\u003c\/strong\u003e Multi-colored\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 808282161484\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.01 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOEM Cross Reference:\u003c\/strong\u003e GLM 30610, Evinrude\/Johnson 310058, Mallory 9-60002, Mercury 27-62386, 27-62386001\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eJohnson\/Evinrude 200 HP outboards, 1977-83\u003c\/li\u003e\n\u003cli\u003eJohnson\/Evinrude 235 HP outboards, 1978-85\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eGLM 30610\u003c\/li\u003e\n\u003cli\u003eEvinrude\/Johnson 310058\u003c\/li\u003e\n\u003cli\u003eMallory 9-60002\u003c\/li\u003e\n\u003cli\u003eMercury 27-62386\u003c\/li\u003e\n\u003cli\u003eMercury 27-62386001\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat engines does the Sierra 18-0182-9 thermostat gasket fit?\u003c\/strong\u003e It fits Johnson\/Evinrude outboards rated at 200 HP built from 1977-83 and 235 HP built from 1978-85.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow many gaskets are in one package?\u003c\/strong\u003e The Sierra 18-0182-9 comes as a pack of 2 thermostat gaskets, giving you a spare or enough for a two-bank service job.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-0182-9 interchangeable with other brands?\u003c\/strong\u003e Yes, it cross-references to GLM 30610, Evinrude\/Johnson 310058, Mallory 9-60002, and Mercury 27-62386 \/ 27-62386001, so it can be ordered under any of those numbers.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat shape and color is this gasket?\u003c\/strong\u003e The 18-0182-9 gasket is round in shape with a multi-colored appearance.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the Sierra 18-0182-9 pack weigh?\u003c\/strong\u003e The pack weighs 0.01 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs this a genuine OEM part or an aftermarket replacement?\u003c\/strong\u003e The Sierra 18-0182-9 is an aftermarket thermostat gasket built to meet or exceed the quality of the original equipment part it replaces.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is the UPC for the Sierra 18-0182-9 thermostat gasket?\u003c\/strong\u003e The UPC is 808282161484.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the Sierra 18-0182-9 work on a 225 HP Johnson\/Evinrude outboard?\u003c\/strong\u003e No, the fitment for the 18-0182-9 covers 200 HP (1977-83) and 235 HP (1978-85) models; other horsepower and year ranges use a different Sierra thermostat gasket part number.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat comes in the box with this purchase?\u003c\/strong\u003e Each order includes 2 Sierra 18-0182-9 thermostat gaskets and nothing else.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan the Mercury 27-62386 gasket be used in place of the Sierra 18-0182-9?\u003c\/strong\u003e Yes, Mercury 27-62386 (and 27-62386001) is one of the cross-reference numbers for the Sierra 18-0182-9, so either number will get you the same gasket.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988029649115,"sku":"SIE-18-0182-9","price":3.09,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/18-0182-9__25311.1722487561.500.750.jpg?v=1785188852"},{"product_id":"thermostat-gasket-for-mercury-outboards-replaces-oem-27-14318-2-27-14318-3-mpn-118-0323","title":"Sierra Thermostat Gasket 18-0323 for Mercury Outboard Engines","description":"\u003cp\u003eThe Sierra 18-0323 is a thermostat gasket engineered for Mercury outboard engines. It seats between the thermostat housing and the engine block or cylinder head, creating the seal that keeps the cooling system's water flow contained and prevents leaks at the thermostat housing joint. Over time, factory gaskets can compress, harden, or tear, which allows water to seep past the housing and can lead to overheating or coolant loss; replacing the gasket with the Sierra 18-0323 restores a tight seal at this connection point.\u003c\/p\u003e\u003cp\u003eThis is a small, single-use component intended to be installed whenever the thermostat housing is opened, whether for a thermostat replacement, inspection, or general cooling system maintenance on a Mercury outboard. Keeping a spare on hand is useful for any outboard owner who services their own cooling system, since the gasket should be replaced rather than reused each time the housing is removed.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-0323\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Type:\u003c\/strong\u003e Thermostat Gasket\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eApplication:\u003c\/strong\u003e Mercury Outboard Engines\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.01 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 030999873125\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat is the Sierra 18-0323 used for?\u003c\/strong\u003e It is a thermostat gasket that seals the thermostat housing on Mercury outboard engines, preventing water from leaking past the housing joint.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhich engines does the Sierra 18-0323 fit?\u003c\/strong\u003e The Sierra 18-0323 thermostat gasket is designed for use on Mercury outboard engines.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-0323 a genuine Sierra part?\u003c\/strong\u003e Yes, part number 18-0323 is manufactured and sold under the Sierra brand.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the Sierra 18-0323 gasket weigh?\u003c\/strong\u003e The Sierra 18-0323 thermostat gasket weighs 0.01 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat comes in the package for the 18-0323?\u003c\/strong\u003e The Sierra 18-0323 is sold as a single thermostat gasket.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhen should I replace the thermostat gasket on my Mercury outboard?\u003c\/strong\u003e Any time the thermostat housing on a Mercury outboard is removed, such as for a thermostat replacement or cooling system inspection, the gasket underneath it, like the Sierra 18-0323, should be replaced rather than reused since it will not reseal reliably once disturbed.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan a worn thermostat gasket cause overheating?\u003c\/strong\u003e A compressed or torn thermostat housing gasket can allow water to leak past the seal, which can reduce cooling efficiency; the Sierra 18-0323 replaces that gasket to restore a proper seal.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is the UPC for the Sierra 18-0323 gasket?\u003c\/strong\u003e The UPC for the Sierra 18-0323 thermostat gasket is 030999873125.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988062941403,"sku":"SIE-18-0323","price":2.07,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-0323_lg__19292.1558120597.500.750.jpg?v=1785329185"},{"product_id":"sierra-18-0398-9-thermostat-gasket-replaces-mercruiser-27-33918-27-8m2021920-for-mercruiser-volvo-penta-pack-of-2","title":"Sierra 18-0398-9 Thermostat Gasket, Pack of 2, Replaces Mercruiser 27-33918 and OMC 385211","description":"\u003cp\u003eThe Sierra 18-0398-9 thermostat gasket seals the thermostat housing on compatible marine engines, providing a leak-free seal between the housing and the engine block or manifold. Sold in a pack of two, it gives boat owners and technicians enough material on hand to complete a full thermostat service or to keep a spare for the next maintenance interval. The gasket is manufactured by Sierra to meet or exceed the quality of the original equipment part it replaces, making it a straightforward drop-in during a thermostat replacement, cooling system inspection, or general engine maintenance.\u003c\/p\u003e\u003cp\u003eBecause thermostat housings and gaskets are shared across several engine brands, the 18-0398-9 cross-references to a range of OEM part numbers from Mercruiser, OMC, Volvo Penta, GLM, and Mallory, so it can be ordered using whichever number appears on the old gasket or in the engine's parts manual. Its light weight and simple flat-gasket design make it easy to install with basic hand tools once the old thermostat and gasket are removed and the mating surfaces are cleaned.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-0398-9\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Type:\u003c\/strong\u003e Thermostat Gasket\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePackage Quantity:\u003c\/strong\u003e Pack of 2\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.01 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 808282161569\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cp\u003eFits engines that use a thermostat housing gasket cross-referenced to the Mercruiser, OMC, Volvo Penta, GLM, and Mallory part numbers listed below.\u003c\/p\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eGLM 35060\u003c\/li\u003e\n\u003cli\u003eMallory 9-60009\u003c\/li\u003e\n\u003cli\u003eMercruiser 27-33918\u003c\/li\u003e\n\u003cli\u003eMercruiser 27-8M2021920\u003c\/li\u003e\n\u003cli\u003eOMC 385211\u003c\/li\u003e\n\u003cli\u003eOMC 312797\u003c\/li\u003e\n\u003cli\u003eVolvo Penta 835417\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat does the Sierra 18-0398-9 thermostat gasket cross-reference to?\u003c\/strong\u003e The Sierra 18-0398-9 thermostat gasket is interchangeable with GLM 35060, Mallory 9-60009, Mercruiser 27-33918, Mercruiser 27-8M2021920, OMC 385211, OMC 312797, and Volvo Penta 835417.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow many gaskets come with an order of 18-0398-9?\u003c\/strong\u003e This listing for the Sierra 18-0398-9 thermostat gasket is priced and sold as a pack of two gaskets.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the 18-0398-9 gasket meet original equipment quality?\u003c\/strong\u003e Yes, the Sierra 18-0398-9 thermostat gasket is manufactured to meet or exceed the quality of the original equipment part it replaces.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWill this gasket fit a Mercruiser engine thermostat housing?\u003c\/strong\u003e Yes, the Sierra 18-0398-9 gasket cross-references to Mercruiser part numbers 27-33918 and 27-8M2021920.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the 18-0398-9 gasket compatible with OMC engines?\u003c\/strong\u003e Yes, it cross-references to OMC part numbers 385211 and 312797.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the Sierra 18-0398-9 gasket work on Volvo Penta engines?\u003c\/strong\u003e Yes, the Sierra 18-0398-9 thermostat gasket cross-references to Volvo Penta part number 835417.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the 18-0398-9 thermostat gasket weigh?\u003c\/strong\u003e The Sierra 18-0398-9 thermostat gasket weighs 0.01 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat UPC is used for the Sierra 18-0398-9 gasket?\u003c\/strong\u003e The Sierra 18-0398-9 thermostat gasket is identified by UPC 808282161569.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow do I confirm 18-0398-9 is the correct gasket for my engine?\u003c\/strong\u003e Match the part number stamped on your old thermostat gasket, or your engine's parts manual, against the cross-reference numbers for the Sierra 18-0398-9: GLM 35060, Mallory 9-60009, Mercruiser 27-33918, Mercruiser 27-8M2021920, OMC 385211, OMC 312797, or Volvo Penta 835417.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs this a genuine Sierra part or a generic aftermarket copy?\u003c\/strong\u003e The 18-0398-9 is manufactured and sold under the Sierra brand, part number 18-0398-9, rather than an unbranded generic part.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is included when I purchase the 18-0398-9 gasket?\u003c\/strong\u003e An order of Sierra 18-0398-9 includes two thermostat gaskets, sold as a pack.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan the 18-0398-9 gasket be used with a Mallory or GLM thermostat housing?\u003c\/strong\u003e Yes, the Sierra 18-0398-9 thermostat gasket cross-references to GLM 35060 and Mallory 9-60009.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988073132251,"sku":"SIE-18-0398-9","price":5.7,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-0398-9__19628.1737854133.500.750.jpg?v=1785188003"},{"product_id":"sierra-18-0844-thermostat-cover-gasket-replaces-yamaha-688-12414-a1-00-fits-yamaha-t60-t9-9-outboards","title":"Sierra Thermostat Cover Gasket 18-0844, Replaces Yamaha 688-12414-A1-00","description":"\u003cp\u003eThe Sierra 18-0844 is a thermostat cover gasket engineered to seal the thermostat housing on applicable Yamaha outboard engines. It forms the seal between the thermostat cover and the powerhead, preventing coolant leaks at this junction and ensuring the cooling system maintains proper pressure and flow around the thermostat. Sierra manufactures this gasket to meet or exceed the quality of the original equipment part it replaces, giving boat owners a reliable option when servicing the cooling system or replacing a worn or damaged gasket during a thermostat swap.\u003c\/p\u003e\u003cp\u003eThis gasket is a simple but essential wear item: over time, heat cycling and engine vibration can cause the original gasket material to harden, crack, or lose its seal, leading to coolant seepage around the thermostat cover. Replacing it whenever the thermostat cover is removed, such as during a thermostat replacement or cooling system inspection, is standard practice to avoid leaks after reassembly. The Sierra 18-0844 is sized and shaped to match the OEM thermostat cover gasket it replaces, so no modification is needed for installation.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-0844\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Type:\u003c\/strong\u003e Thermostat Cover Gasket\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.01 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eQuantity:\u003c\/strong\u003e 1 gasket\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 030999874771\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\u003cli\u003eYamaha outboard engines using thermostat cover OEM part 688-12414-A1-00\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\u003cli\u003e688-12414-A1-00\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat does the Sierra 18-0844 gasket fit?\u003c\/strong\u003e The Sierra 18-0844 is a thermostat cover gasket for Yamaha outboard engines that use the OEM thermostat cover gasket 688-12414-A1-00.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-0844 the same as the Yamaha OEM gasket?\u003c\/strong\u003e Yes, the Sierra 18-0844 replaces Yamaha OEM part 688-12414-A1-00 and is built to meet or exceed the original equipment part's quality.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow many gaskets are included with part 18-0844?\u003c\/strong\u003e One thermostat cover gasket is included per Sierra 18-0844 package.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is the weight of the 18-0844 gasket?\u003c\/strong\u003e The 18-0844 thermostat cover gasket weighs 0.01 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhen should this gasket be replaced?\u003c\/strong\u003e Replace the 18-0844 gasket any time the thermostat cover is removed, such as during a thermostat inspection or replacement, since the old gasket material can lose its seal after being disturbed.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat happens if a worn thermostat cover gasket is not replaced?\u003c\/strong\u003e A worn or hardened thermostat cover gasket can allow coolant to leak at the thermostat housing, so installing a fresh 18-0844 gasket during service helps prevent seepage.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the Sierra 18-0844 include the thermostat itself?\u003c\/strong\u003e No, the 18-0844 is the cover gasket only; it does not include the thermostat.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat material is the 18-0844 gasket made from?\u003c\/strong\u003e The 18-0844 thermostat cover gasket is made from OEM-equivalent gasket material to match the original Yamaha part.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs Sierra 18-0844 genuine Yamaha or aftermarket?\u003c\/strong\u003e The 18-0844 is a Sierra-manufactured aftermarket gasket, made to meet or exceed the specifications of the original Yamaha equipment it replaces.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan the 18-0844 gasket be reused after removal?\u003c\/strong\u003e Thermostat cover gaskets like the 18-0844 are designed for one-time installation; once removed, the seal is generally compromised and a new gasket should be installed.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988085780699,"sku":"SIE-18-0844","price":4.16,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-0844_lg__45154.1558121240.500.750.jpg?v=1785188585"},{"product_id":"thermostat-gasket-for-mercury-outboard-replaces-27-14318-2-27-14318-3-sierra-18-0835","title":"Sierra Thermostat Gasket 18-0835 - Replaces Yamaha 62Y-12414-00-00 for Yamaha 2-Stroke Outboards","description":"\u003cp\u003eThe Sierra 18-0835 is a thermostat gasket built for Yamaha 2-stroke outboard cooling systems. It seals the mating surface between the thermostat and its housing, keeping coolant flow contained and preventing leaks that can lead to overheating. This gasket is the direct cross-reference equivalent of Yamaha OEM part number 62Y-12414-00-00, so it installs as a straightforward replacement using the same mounting points and sealing surface as the original equipment part.\u003c\/p\u003e\u003cp\u003eAs part of Sierra's outboard cooling system lineup, this gasket is intended to be replaced any time the thermostat is serviced or replaced, since a reused gasket can lose its seal integrity. It is a lightweight, single-use component sold individually (quantity of 1 per thermostat).\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-0835\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Type:\u003c\/strong\u003e Thermostat Gasket\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOEM Cross Reference:\u003c\/strong\u003e 62Y-12414-00-00\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eApplication:\u003c\/strong\u003e Yamaha 2-Stroke Outboard Cooling System\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.01 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 808282265441\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eQuantity per Engine:\u003c\/strong\u003e 1\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\u003cli\u003eYamaha 2-stroke outboard engines (cooling system \/ thermostat housing)\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\u003cli\u003e62Y-12414-00-00\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat does the Sierra 18-0835 thermostat gasket fit?\u003c\/strong\u003e The Sierra 18-0835 is designed for Yamaha 2-stroke outboard cooling systems, sealing the thermostat housing on these engines.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat OEM part number does 18-0835 replace?\u003c\/strong\u003e It replaces Yamaha OEM part number 62Y-12414-00-00, making it a direct cross-reference for that gasket.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the 62Y-12414-00-00 gasket the same as the Sierra 18-0835?\u003c\/strong\u003e Yes, Sierra part 18-0835 is the equivalent to Yamaha OEM number 62Y-12414-00-00 and can be used in its place.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does this thermostat gasket weigh?\u003c\/strong\u003e The 18-0835 thermostat gasket weighs 0.01 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow many gaskets are included when ordering 18-0835?\u003c\/strong\u003e One 18-0835 thermostat gasket is included, matching the quantity of 1 per engine listed for this application.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhen should I replace the thermostat gasket on a Yamaha 2-stroke outboard?\u003c\/strong\u003e The 18-0835 gasket should be replaced any time the thermostat is removed or serviced on a Yamaha 2-stroke outboard, since reinstalling a used gasket can compromise the seal.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the 18-0835 gasket come with a thermostat?\u003c\/strong\u003e No, 18-0835 is the gasket only; it does not include a thermostat as part of the package.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat does a thermostat gasket like 18-0835 actually do?\u003c\/strong\u003e It seals the joint between the thermostat and its housing on the Yamaha 2-stroke outboard cooling system, preventing coolant leaks at that connection.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs Sierra 18-0835 a genuine cross-reference part or a generic substitute?\u003c\/strong\u003e It is sold as a direct cross-reference replacement for Yamaha OEM number 62Y-12414-00-00, matching that part's application in the Yamaha cooling system.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is the UPC for the Sierra 18-0835 thermostat gasket?\u003c\/strong\u003e The UPC for the 18-0835 thermostat gasket is 808282265441.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988085911771,"sku":"SIE-18-0835","price":4.63,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-0835_lg__38602.1558121050.500.750.jpg?v=1785329185"},{"product_id":"thermostat-cover-gasket-2-pack-replaces-rm0003-marine-engine","title":"Sierra Thermostat Gasket 18-0878-9, Replaces RM0003, Pack of 2","description":"\u003cp\u003eThis Sierra thermostat gasket seals the thermostat housing on the engine, creating the seal needed to prevent coolant leaks at the mating surface between the thermostat cover and the engine block or housing. It is sold as part number 18-0878-9 and is packaged two gaskets per package, so you have a spare on hand or enough for a job that requires servicing more than one housing. Thermostat gaskets are a wear item that should be replaced any time the thermostat cover is removed, since reusing an old gasket can result in a coolant leak or an improper seal even if the gasket appears undamaged. This part is a direct equivalent for OEM number RM0003, making it a straightforward replacement when that OEM number is called for. Keeping a correct-fit thermostat gasket on hand is a low-cost way to avoid downtime during routine cooling system maintenance, thermostat replacement, or housing inspection.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-0878-9\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Type:\u003c\/strong\u003e Thermostat Gasket\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePackage Quantity:\u003c\/strong\u003e 2 gaskets per package\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.02 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 808282161828\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\u003cli\u003eRM0003\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eHow many gaskets come in this package?\u003c\/strong\u003e Sierra part number 18-0878-9 is sold two gaskets per package, priced per package.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat OEM number does this thermostat gasket replace?\u003c\/strong\u003e This gasket replaces OEM number RM0003.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs this gasket a genuine OEM part or an aftermarket equivalent?\u003c\/strong\u003e The 18-0878-9 is a Sierra-branded replacement gasket that is a direct equivalent for OEM number RM0003, not an OEM-branded part.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does this gasket weigh?\u003c\/strong\u003e The 18-0878-9 thermostat gasket weighs 0.02 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhen should I replace the thermostat gasket?\u003c\/strong\u003e Any time the thermostat cover is removed for inspection or thermostat replacement, the gasket should be replaced rather than reused, since a used gasket can leak even without visible damage.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is this gasket used for?\u003c\/strong\u003e It seals the thermostat housing to prevent coolant leaks at the mating surface between the thermostat cover and the engine, and is identified by Sierra part number 18-0878-9.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan I buy just one gasket instead of the pack of two?\u003c\/strong\u003e Part number 18-0878-9 is sold and priced only as a package of 2 gaskets.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes this gasket fit if my engine calls for OEM part RM0003?\u003c\/strong\u003e Yes, part number 18-0878-9 is the listed replacement for OEM number RM0003.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is included when I order this part?\u003c\/strong\u003e Ordering 18-0878-9 gets you one package containing 2 thermostat gaskets.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat category of engine part is this?\u003c\/strong\u003e The 18-0878-9 gasket is categorized as an engine accessory, specifically a thermostat gasket.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988086042843,"sku":"SIE-18-0878-9","price":3.52,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-0878_lg__90235.1692043126.500.750.jpg?v=1785329186"},{"product_id":"thermostat-cover-gasket-for-omc-evinrude-outboards-replaces-oem-329830-sierra-18-1202","title":"Sierra Thermostat Gasket 18-1202, Replaces 332369, V-4 Engines, Pack of 2","description":"\u003cp\u003eThe Sierra 18-1202 thermostat gasket seals the thermostat housing to the engine block, preventing coolant leaks and maintaining proper cooling system pressure on V-4 marine engines. This gasket is a direct fit replacement designed to restore a tight, leak-free seal whenever a thermostat is serviced, replaced, or inspected. Because a worn or hardened gasket is one of the most common causes of coolant seepage around the thermostat housing, replacing it at the same time as the thermostat -- or whenever the housing is removed for any reason -- helps prevent repeat leaks and re-work. The 18-1202 is sold as a pack of 2, giving the installer a spare on hand or enough material to service two thermostat housings in one job. It is built to the dimensions and specifications of the original equipment gasket it replaces, so it seats correctly against the mating surfaces without additional trimming or fitting. This gasket is intended for V-4 marine engine applications and directly replaces OEM part number 332369. Keeping a genuine Sierra gasket in inventory ensures the correct thickness and material compression for a proper seal, avoiding the leaks and reduced engine performance that can result from using an incorrectly sized or generic gasket.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-1202\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Type:\u003c\/strong\u003e Thermostat Gasket\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eEngine Fitment:\u003c\/strong\u003e V-4\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePackage Quantity:\u003c\/strong\u003e 2 gaskets per pack\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.02 pounds\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\u003cli\u003eV-4 marine engines\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\u003cli\u003e332369\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat does the Sierra 18-1202 thermostat gasket fit?\u003c\/strong\u003e The Sierra 18-1202 thermostat gasket is designed for V-4 marine engines and directly replaces OEM part number 332369.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow many gaskets come in a pack of the 18-1202?\u003c\/strong\u003e Each pack of the Sierra 18-1202 thermostat gasket contains 2 gaskets, enough to service two thermostat housing installations or keep a spare on hand.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs OEM number 332369 the same part as Sierra 18-1202?\u003c\/strong\u003e Yes, the Sierra 18-1202 thermostat gasket is a direct replacement for OEM part number 332369.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhere is this gasket used on the engine?\u003c\/strong\u003e This gasket seals the thermostat housing to the engine block on V-4 marine engines, sealing the coolant passage around the thermostat.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhen should the thermostat gasket be replaced?\u003c\/strong\u003e The 18-1202 gasket should be replaced any time the thermostat housing is removed, such as during thermostat replacement, inspection, or if coolant leakage is present around the housing.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the pack include the thermostat itself?\u003c\/strong\u003e No, the Sierra 18-1202 is a gasket only; it does not include the thermostat. It is intended to be used when installing or servicing a thermostat.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the 18-1202 gasket weigh?\u003c\/strong\u003e The Sierra 18-1202 thermostat gasket weighs 0.02 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-1202 a genuine OEM part or aftermarket?\u003c\/strong\u003e The 18-1202 is a Sierra-branded replacement part manufactured to match the fit and function of OEM part 332369 for V-4 marine engines.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan this gasket be reused after removal?\u003c\/strong\u003e Gaskets compress to form a seal during installation, so the 18-1202 thermostat gasket should be replaced with a new one each time the thermostat housing is removed rather than reused.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWill this gasket fit engines other than V-4?\u003c\/strong\u003e The Sierra 18-1202 thermostat gasket is specified for V-4 marine engines; fitment outside that engine type is not listed for this part number.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988086927579,"sku":"SIE-18-1202","price":5.55,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-1202__89857.1737886973.500.750.jpg?v=1785189022"},{"product_id":"thermostat-diaphragm-gasket-for-evinrude-johnson-v-4-v-6-loop-charge-replaces-omc-394408-sierra-18-1222","title":"Sierra 18-1222 Thermostat Diaphragm Gasket, Johnson\/Evinrude V4\/V6 200\/225 HP 1988-93, Replaces OMC 394408","description":"\u003cp\u003eThe Sierra 18-1222 is a round thermostat diaphragm gasket for Johnson\/Evinrude V4\/V6 loop charge outboard engines. It seals the thermostat housing to the powerhead, maintaining proper cooling system pressure and preventing water leakage around the thermostat. This gasket is manufactured to meet or exceed original equipment specifications, making it a direct equivalent for the OEM diaphragm gasket used on covered Johnson\/Evinrude V4\/V6 outboards.\u003c\/p\u003e\u003cp\u003eThe gasket is a round, white component sized to match the OEM thermostat housing footprint on applicable Johnson\/Evinrude V4\/V6 powerheads. It is commonly replaced whenever the thermostat itself is serviced, since a worn or hardened gasket is a frequent source of coolant leaks and overheating on outboard motors. Fitment covers 200 HP and 225 HP Johnson\/Evinrude outboards for the 1988-93 model years.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-1222\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Type:\u003c\/strong\u003e Thermostat Diaphragm Gasket\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eShape:\u003c\/strong\u003e Round\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eColor:\u003c\/strong\u003e White\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.01 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 030999752376\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOEM Cross Reference:\u003c\/strong\u003e GLM 46130, 394408\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eJohnson\/Evinrude V4\/V6 loop charge outboard, 200 HP, 1988-93\u003c\/li\u003e\n\u003cli\u003eJohnson\/Evinrude V4\/V6 loop charge outboard, 225 HP, 1988-93\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eGLM 46130\u003c\/li\u003e\n\u003cli\u003e394408\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat engines does the Sierra 18-1222 thermostat diaphragm gasket fit?\u003c\/strong\u003e The Sierra 18-1222 fits Johnson\/Evinrude V4\/V6 loop charge outboard engines rated at 200 HP and 225 HP for the 1988-93 model years.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-1222 a direct OEM equivalent?\u003c\/strong\u003e Yes, the 18-1222 is interchangeable with GLM 46130 and OEM number 394408, and it meets or exceeds the quality of the original equipment part it replaces.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat OEM part numbers does 18-1222 cross-reference to?\u003c\/strong\u003e 18-1222 crosses to GLM 46130 and OMC\/Evinrude\/Johnson 394408.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat shape and color is this gasket?\u003c\/strong\u003e The 18-1222 thermostat diaphragm gasket is round and white.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the Sierra 18-1222 gasket weigh?\u003c\/strong\u003e It weighs 0.01 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eShould the thermostat diaphragm gasket be replaced when installing a new thermostat?\u003c\/strong\u003e Yes, replacing the 18-1222 gasket whenever the thermostat is serviced helps prevent coolant leaks caused by a worn or hardened seal at the thermostat housing.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is included with the Sierra 18-1222?\u003c\/strong\u003e The 18-1222 is sold as a single thermostat diaphragm gasket.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-1222 genuine Sierra or aftermarket?\u003c\/strong\u003e It is a genuine Sierra-branded part manufactured to meet or exceed the OEM specification for part 394408, not a generic aftermarket substitute.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is the UPC for the Sierra 18-1222 gasket?\u003c\/strong\u003e The UPC is 030999752376.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the 18-1222 gasket work on 235 HP or 200 HP 1977-83 Johnson\/Evinrude engines?\u003c\/strong\u003e No, the 18-1222 is specified for 200 HP and 225 HP Johnson\/Evinrude V4\/V6 outboards built 1988-93; earlier 200 HP (1977-83) and 235 HP applications use a different Sierra thermostat gasket.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988087058651,"sku":"SIE-18-1222","price":14.38,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-1222_lg__91690.1558121932.500.750.jpg?v=1785188297"},{"product_id":"grommet-for-evinrude-johnson-omc-v-6-crossflow-outboards-replaces-omc-320880-sierra-18-1221-18-1221-9-2-pack","title":"Sierra Retainer Gasket 18-1221-9, 2-Pack, Fits Johnson\/Evinrude 200 HP and 225 HP (1988-93)","description":"\u003cp\u003eThe Sierra Retainer Gasket 18-1221-9 is a two-pack replacement gasket used with the thermostat retainer on select Johnson\/Evinrude (OMC\/BRP) outboard powerheads. This gasket seals the retainer housing that holds the thermostat in place within the cooling system, helping maintain proper sealing pressure and preventing coolant leakage around the retainer during operation. Sold as a set of two, it gives an installer a spare on hand for a follow-up service or a second engine, which is useful since gaskets should be replaced any time the retainer is removed rather than reused. This part is specifically called out in Sierra's application charts for Johnson\/Evinrude 200 HP outboards built 1988-93 and 225 HP outboards built 1988-93, distinguishing it from the separate part number used on earlier 185 HP, 200 HP (1977-83), and 235 HP models in the same engine family. Confirming the exact HP and year of the outboard before ordering ensures the correct retainer gasket is installed, since Sierra lists a different part number for those other model years. As with any gasket, proper surface prep and correct torque on the retainer hardware during reassembly are important to achieve a good seal.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-1221-9\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePackage Quantity:\u003c\/strong\u003e 2 gaskets\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.03 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCategory:\u003c\/strong\u003e Thermostat Retainer Gasket\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 808282162368\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFitment:\u003c\/strong\u003e Johnson\/Evinrude (OMC\/BRP) 200 HP (1988-93), 225 HP (1988-93)\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eJohnson\/Evinrude (OMC\/BRP) 200 HP, 1988-93\u003c\/li\u003e\n\u003cli\u003eJohnson\/Evinrude (OMC\/BRP) 225 HP, 1988-93\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\u003cli\u003eNo OEM cross-reference numbers are listed for this part.\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat is the Sierra 18-1221-9 retainer gasket used for?\u003c\/strong\u003e It seals the thermostat retainer on the powerhead of compatible Johnson\/Evinrude (OMC\/BRP) outboards, part 18-1221-9, helping the retainer housing hold pressure and keep coolant from leaking around the thermostat area.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow many gaskets come in the Sierra 18-1221-9 package?\u003c\/strong\u003e Two retainer gaskets are included in each 18-1221-9 package, giving you a spare for a future service.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhich outboards does part 18-1221-9 fit?\u003c\/strong\u003e Sierra's application chart lists 18-1221-9 for Johnson\/Evinrude (OMC\/BRP) 200 HP outboards built 1988-93 and 225 HP outboards built 1988-93.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes 18-1221-9 fit earlier 200 HP Johnson\/Evinrude outboards from the 1970s and 80s?\u003c\/strong\u003e No. Sierra's chart shows a different retainer gasket part number for 200 HP models built 1977-83, so 18-1221-9 is specific to the 1988-93 200 HP and 225 HP applications.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs 18-1221-9 the same gasket used on 185 HP or 235 HP Johnson\/Evinrude models?\u003c\/strong\u003e No. Those horsepower ratings (185 HP 1984-85 and 235 HP 1978-85) use a different Sierra part number in the same application chart, not 18-1221-9.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the Sierra 18-1221-9 gasket set weigh?\u003c\/strong\u003e The 18-1221-9 two-pack weighs 0.03 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eShould the retainer gasket be reused after removing the thermostat retainer?\u003c\/strong\u003e No, a fresh gasket like the Sierra 18-1221-9 should be installed any time the thermostat retainer is removed, since a used gasket may not reseal properly.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-1221-9 gasket genuine OEM or an aftermarket replacement?\u003c\/strong\u003e The 18-1221-9 is a Sierra-branded replacement gasket manufactured to fit the specified Johnson\/Evinrude outboard applications; no OEM cross-reference number is listed for it in Sierra's catalog.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is included when I order part 18-1221-9?\u003c\/strong\u003e Ordering 18-1221-9 gets you a package of two thermostat retainer gaskets; no other hardware or thermostat is included.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat UPC is associated with the Sierra 18-1221-9 gasket 2-pack?\u003c\/strong\u003e The UPC for the 18-1221-9 two-pack is 808282162368.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988087091419,"sku":"SIE-18-1221-9","price":2.42,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-1221-9_lg__11130.1722348497.500.750.jpg?v=1785329181"},{"product_id":"sierra-18-1507-thermostat-seal-replaces-omc-335981-fits-evinrude-johnson-60-degree-v-4-v-6-outboards","title":"Sierra 143 Degree Marine Thermostat, Replaces 436195, Part Number 18-1507","description":"\u003cp\u003eThe Sierra 18-1507 is a 143 degree F marine engine thermostat, engineered as a direct replacement for outboard and sterndrive cooling systems that call for a 143 degree opening temperature. The thermostat regulates coolant flow through the engine block, staying closed until the powerhead reaches its designed operating temperature and then opening to allow water flow to the cooling passages. Maintaining the correct opening temperature is critical for marine engines: running too cool can lead to poor combustion and increased wear, while a failed or stuck thermostat can cause overheating and serious engine damage.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-1507\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Type:\u003c\/strong\u003e Thermostat\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTemperature Rating:\u003c\/strong\u003e 143 degrees F\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.01 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUnit Count:\u003c\/strong\u003e 1\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 808282167127\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOEM Cross Reference:\u003c\/strong\u003e 436195\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cp\u003eDesigned as a direct fit for engines specifying a 143 degree F opening thermostat.\u003c\/p\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\u003cli\u003e436195\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat temperature does the Sierra 18-1507 thermostat open at?\u003c\/strong\u003e The Sierra 18-1507 opens at 143 degrees F, which is the rated temperature stamped for this part.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat OEM part number does 18-1507 replace?\u003c\/strong\u003e It replaces OEM number 436195, so it can be used as a direct substitute for that original thermostat.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does this thermostat weigh?\u003c\/strong\u003e The Sierra 18-1507 thermostat weighs 0.01 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow many thermostats come in a package?\u003c\/strong\u003e Each Sierra 18-1507 package contains a single thermostat unit.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-1507 a genuine Sierra part or aftermarket?\u003c\/strong\u003e It is a Sierra-branded thermostat manufactured under Sierra's own part number, 18-1507.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is the UPC for this part?\u003c\/strong\u003e The Sierra 18-1507 thermostat carries UPC 808282167127.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat happens if a marine thermostat like the 18-1507 fails?\u003c\/strong\u003e A stuck or failed thermostat can prevent proper coolant flow, leading to engine overheating or, if stuck open, slower warm-up and reduced efficiency, which is why matching the correct 143 degree rating for part 18-1507 matters.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan I use a different temperature rated thermostat instead of the 143 degree 18-1507?\u003c\/strong\u003e The 18-1507 is specifically rated at 143 degrees F, and using a different opening temperature than the engine manufacturer specifies is not recommended since it changes engine warm-up and operating temperature behavior.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the 18-1507 include a gasket or seal?\u003c\/strong\u003e The listing for part 18-1507 covers the thermostat itself; a separate thermostat seal (such as Sierra 18-1734 or 18-1506) may be needed depending on the engine application.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow do I know if 18-1507 is the right thermostat for my engine?\u003c\/strong\u003e Confirm your engine calls for a 143 degree F thermostat or originally used OEM part 436195, since Sierra 18-1507 is built to that specification.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988087812315,"sku":"SIE-18-1507","price":5.39,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-1507_lg__71663.1558121453.500.750.jpg?v=1785189093"},{"product_id":"sierra-18-1977-1-thermostat-housing-for-mercruiser-i-o-replaces-oem-47441-47441a1-fits-gm-260-225-228-898-198-cooling-systems","title":"Sierra 18-1977-1 Thermostat Housing for Mercruiser 305 cid V-8 (1977-1982), Replaces 4765100, 6218461","description":"\u003cp\u003eThe Sierra 18-1977-1 is a marine thermostat housing built to replace the factory housing on Mercruiser 305 cid V-8 sterndrive engines produced in 1977-1982. It is sand cast and machined to exact specifications, then primed and painted to withstand the harsh marine environment, and is finished in white with a polished surface. The housing mounts to the engine block and holds the thermostat in place while sealing the cooling passages, so a worn, cracked, or corroded original housing is a common reason for coolant leaks, overheating, or an improperly seating thermostat. Installing the 18-1977-1 restores a proper seal at this connection point and returns the cooling system to factory-correct operation.\u003c\/p\u003e\u003cp\u003eThis housing is a direct cross-reference for GM\/Mercruiser OEM housing numbers 4765100 and 6218461, so it fits in place of those original parts on the applicable 305 cid V-8 engines without modification. It ships as a single housing unit and is intended as a like-for-like replacement, not an upgrade kit, so existing thermostats, gaskets, and hardware from the original installation can be reused if they are still in serviceable condition.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-1977-1\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Type:\u003c\/strong\u003e Thermostat Housing\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eEngine Fitment:\u003c\/strong\u003e Mercruiser 305 cid V-8\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eModel Years:\u003c\/strong\u003e 1977-1982\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOEM Cross-Reference:\u003c\/strong\u003e 4765100, 6218461\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 1.51 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePackage Dimensions:\u003c\/strong\u003e 17.6 H x 8.7 L x 12.3 W (centimetres)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMaterial:\u003c\/strong\u003e Metal, sand cast and machined\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFinish:\u003c\/strong\u003e Polished\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eColor:\u003c\/strong\u003e White\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCountry of Origin:\u003c\/strong\u003e China\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 808282198206\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\u003cli\u003eMercruiser 305 cid V-8 engines, 1977-1982\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e4765100\u003c\/li\u003e\n\u003cli\u003e6218461\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat engines does the Sierra 18-1977-1 thermostat housing fit?\u003c\/strong\u003e The Sierra 18-1977-1 fits Mercruiser 305 cid V-8 engines built in 1977-1982.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the 18-1977-1 replace OEM part number 4765100?\u003c\/strong\u003e Yes, the Sierra 18-1977-1 is a direct cross-reference for OEM housing number 4765100 on the applicable 305 cid V-8 Mercruiser engines.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the 18-1977-1 also replace OEM part number 6218461?\u003c\/strong\u003e Yes, 6218461 is the other OEM number the Sierra 18-1977-1 housing replaces on 1977-1982 305 cid V-8 engines.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is the 18-1977-1 housing made of?\u003c\/strong\u003e It is a metal housing that is sand cast and machined to exact specifications, then primed and painted, with a polished white finish for long life in a marine environment.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the Sierra 18-1977-1 thermostat housing weigh?\u003c\/strong\u003e It weighs 1.51 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat are the package dimensions of the 18-1977-1?\u003c\/strong\u003e The packaged housing measures 17.6 H x 8.7 L x 12.3 W in centimetres.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the 18-1977-1 include the thermostat and gasket?\u003c\/strong\u003e The 18-1977-1 is the thermostat housing itself; it ships as a single housing unit.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-1977-1 a genuine Sierra part or aftermarket generic?\u003c\/strong\u003e The 18-1977-1 is manufactured by Sierra, a marine parts brand, and is sold under Sierra's own part number as its housing for this application.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhy would I need to replace my thermostat housing?\u003c\/strong\u003e A cracked, corroded, or leaking original housing on a 305 cid V-8 Mercruiser engine is a common cause of coolant leaks and overheating, and the Sierra 18-1977-1 is built to restore a proper seal in place of the worn factory unit.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhere is the Sierra 18-1977-1 manufactured?\u003c\/strong\u003e The country of origin for the 18-1977-1 housing is China.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat color and finish does the 18-1977-1 come in?\u003c\/strong\u003e The 18-1977-1 housing has a white color with a polished finish.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan I reuse my old thermostat and hardware with the 18-1977-1?\u003c\/strong\u003e Since the 18-1977-1 is a like-for-like replacement housing, an existing thermostat, gasket, and hardware can be reused as long as they are still in serviceable condition.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988089581787,"sku":"SIE-18-1977-1","price":65.17,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/18-1977-1__20869.1722361156.500.750.jpg?v=1785188626"},{"product_id":"sierra-18-1989-thermostat-housing-stainless-steel-replaces-mercruiser-8m0061381-fits-mercruiser-gm-v-8-454-502-cid-7-4l-8-2l","title":"Sierra Thermostat Housing 18-1989, Replaces Mercruiser 8M0061381 861006A1, Fits GM V-8 454\/502 MCM\/MIE","description":"\u003cp\u003eThe Sierra 18-1989 Thermostat Housing is a stainless steel replacement housing built for MCM\/MIE GM V-8 (454 \u0026amp; 502 cid) marine engines. Stainless steel construction resists corrosion in salt and fresh water environments while providing long service life under sustained engine heat and vibration. This housing is manufactured to meet or exceed OEM specifications, giving boat owners a direct, reliable replacement for a worn, cracked, or leaking factory thermostat housing.\u003c\/p\u003e\u003cp\u003eA properly sealed thermostat housing is essential for maintaining correct engine operating temperature, which affects performance improvement and throttle response. The 18-1989 is designed as a direct fit for the applications listed below, and Sierra offers the 18-1989K Thermostat Service Kit as the matching source for the gasket, thermostat, and other service parts needed when installing this housing.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-1989\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Type:\u003c\/strong\u003e Thermostat Housing\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMaterial:\u003c\/strong\u003e Stainless Steel\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 3.9 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFits:\u003c\/strong\u003e MCM\/MIE GM V-8 (454 \u0026amp; 502 cid) engines\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eService Kit:\u003c\/strong\u003e 18-1989K Thermostat Service Kit (for replacement parts)\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\u003cli\u003eMCM\/MIE GM V-8 (454 \u0026amp; 502 cid) engines\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eMercruiser 8M0061381\u003c\/li\u003e\n\u003cli\u003eMercruiser 861006A1\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat engines does the Sierra 18-1989 Thermostat Housing fit?\u003c\/strong\u003e The Sierra 18-1989 Thermostat Housing fits MCM\/MIE GM V-8 (454 \u0026amp; 502 cid) marine engines.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat OEM part numbers does the 18-1989 replace?\u003c\/strong\u003e This housing replaces Mercruiser 8M0061381 and Mercruiser 861006A1, so either OEM number can be used to confirm a correct match to the Sierra 18-1989.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat material is the Sierra 18-1989 Thermostat Housing made of?\u003c\/strong\u003e It is made of stainless steel, chosen for corrosion resistance in marine engine cooling systems exposed to salt and fresh water.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the 18-1989 Thermostat Housing weigh?\u003c\/strong\u003e The Sierra 18-1989 Thermostat Housing weighs 3.9 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the 18-1989 come with a thermostat and gasket?\u003c\/strong\u003e No, the 18-1989 is the housing itself; the matching 18-1989K Thermostat Service Kit provides the replacement parts such as the thermostat and gasket needed for installation.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-1989 a genuine OEM part or aftermarket?\u003c\/strong\u003e The 18-1989 is a Sierra-manufactured aftermarket housing engineered to meet or exceed OEM specifications for Mercruiser 8M0061381 and 861006A1 applications.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhy does a marine engine thermostat housing need to be stainless steel?\u003c\/strong\u003e Stainless steel construction on the Sierra 18-1989 resists the corrosion that raw water cooling systems cause in marine engines, extending service life compared to housings made from less resistant materials.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat should I order along with the 18-1989 housing for a full replacement?\u003c\/strong\u003e Sierra recommends the 18-1989K Thermostat Service Kit alongside the 18-1989 housing for the replacement parts needed to complete the installation.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWill the 18-1989 improve engine performance?\u003c\/strong\u003e A correctly sealed and functioning thermostat housing like the Sierra 18-1989 supports proper engine operating temperature, which contributes to performance improvement and throttle response.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the 18-1989 housing specific to one engine cid, or does it cover multiple sizes?\u003c\/strong\u003e The Sierra 18-1989 is designed for MCM\/MIE GM V-8 engines in both 454 and 502 cid configurations.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988090040539,"sku":"SIE-18-1989","price":251.28,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/xa__61079.1753840676.500.750.jpg?v=1785188531"},{"product_id":"sierra-18-1989k-thermostat-service-kit-for-18-1989-marine-thermostat-housing-mercruiser-8m0061381-861006a1","title":"Sierra 18-1989K Thermostat Service Kit for 18-1989 Thermostat Housing","description":"\u003cp\u003eThe Sierra 18-1989K Thermostat Service Kit provides the replacement parts needed to service the 18-1989 thermostat housing on your marine engine. Rather than replacing the entire housing, this kit lets you restore proper cooling system function with fresh service components sized specifically for that housing, helping maintain correct engine operating temperature and preventing the overheating issues that come from a worn or failing thermostat setup. It is built to a universal fit, making it a straightforward option for boat owners performing routine cooling system maintenance. Sierra engineers its parts to meet or exceed the performance of the original equipment they replace, and the company supplies OEM engine manufacturers and boat builders with parts on a daily basis, so this kit is manufactured to the same standard used across the marine industry. At 0.1 pounds, it is a compact, lightweight kit that is easy to store aboard or in a parts locker until it's needed. Whether you are performing scheduled maintenance or addressing a cooling system problem, the 18-1989K gives you the correct service components matched to the 18-1989 housing without having to source individual parts separately.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-1989K\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Type:\u003c\/strong\u003e Thermostat Service Kit\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCompatible Housing:\u003c\/strong\u003e 18-1989 Thermostat Housing\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFit Type:\u003c\/strong\u003e Universal Fit\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eColor:\u003c\/strong\u003e White\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.1 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUnit Count:\u003c\/strong\u003e 1\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 808282271145\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\u003cli\u003eFits the Sierra 18-1989 Thermostat Housing\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat is the Sierra 18-1989K Thermostat Service Kit for?\u003c\/strong\u003e It is a service kit for the 18-1989 thermostat housing, providing the replacement parts needed to service that housing rather than replacing the whole unit.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWill the 18-1989K fit any boat engine?\u003c\/strong\u003e The 18-1989K is listed as a universal fit kit, sized to match the 18-1989 thermostat housing rather than one specific engine model.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the 18-1989K weigh?\u003c\/strong\u003e This Sierra thermostat service kit weighs 0.1 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat color is the 18-1989K kit?\u003c\/strong\u003e The kit is white.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow many units come in one 18-1989K package?\u003c\/strong\u003e One Sierra 18-1989K Thermostat Service Kit is included per unit count of 1.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the 18-1989K a genuine Sierra part or aftermarket?\u003c\/strong\u003e It is a genuine Sierra part, manufactured to meet or exceed the performance of the original equipment it replaces.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the 18-1989K come with a warranty?\u003c\/strong\u003e Yes, the Sierra 18-1989K Thermostat Service Kit is covered by a limited warranty.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is the UPC for the Sierra 18-1989K?\u003c\/strong\u003e The UPC for the Sierra 18-1989K Thermostat Service Kit is 808282271145.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDo I need to replace the entire thermostat housing to use this kit?\u003c\/strong\u003e No, the 18-1989K is specifically a service kit designed to refresh the 18-1989 thermostat housing without replacing the full housing assembly.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWho makes the 18-1989K thermostat service kit?\u003c\/strong\u003e Sierra manufactures the 18-1989K, and the company supplies parts to OEM engine manufacturers and boat builders as part of its regular production.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988090138843,"sku":"SIE-18-1989K","price":16.87,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/18-1989K__90158.1739459150.500.750.jpg?v=1785188003"},{"product_id":"sierra-18-2553-9-thermostat-cover-gasket-replaces-mercruiser-27-47510-for-mercruiser-gm-v-6-v-8-pack-of-2","title":"Sierra 18-2553-9 Thermostat Cover Gasket - Pack of 2, Replaces Mercruiser 27-47510, Fits MCM\/MIE GM V-6 \u0026 V-8 Engines","description":"\u003cp\u003eThe Sierra 18-2553-9 Thermostat Cover Gasket seals the thermostat housing on MCM\/MIE GM V-6 and V-8 marine engines equipped with the older style two-piece thermostat housing. Sold as a pack of 2, this gasket ensures the housing forms a tight seal against the exhaust manifold or thermostat cover, preventing coolant leaks and maintaining proper engine operating temperature. It is built to Sierra's quality standard, which is designed to meet or exceed the original equipment part it replaces, giving boat owners a reliable, OEM-equivalent seal for routine thermostat service or replacement. This gasket is commonly needed whenever the thermostat cover is removed for cleaning, inspection, or thermostat replacement, since reusing an old gasket can lead to leaks. It directly interchanges with several OEM and aftermarket part numbers, making it easy to source a correct-fit replacement regardless of which brand's part number is printed on your old housing. Keeping a spare pack on hand is useful for owners who service their own MerCruiser sterndrive engines, since the gasket is inexpensive relative to the cost of a coolant leak or an engine that runs hot due to a failed seal.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-2553-9\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Type:\u003c\/strong\u003e Thermostat Cover Gasket\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePackage Quantity:\u003c\/strong\u003e 2\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.02 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 808282162870\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eGTIN:\u003c\/strong\u003e 00808282162870\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFitment:\u003c\/strong\u003e MCM\/MIE GM V-6 \u0026amp; V-8 engines with older style 2-piece thermostat housing\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e898 305 cid V-8, 1983-1984\u003c\/li\u003e\n\u003cli\u003eMCM\/MIE GM V-6 \u0026amp; V-8 engines with older style 2-piece thermostat housing\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eGLM 31460\u003c\/li\u003e\n\u003cli\u003eMallory 9-60005\u003c\/li\u003e\n\u003cli\u003eMercruiser 27-47510\u003c\/li\u003e\n\u003cli\u003eMercruiser 27-47510Q\u003c\/li\u003e\n\u003cli\u003eOsco 47510\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat engines does the Sierra 18-2553-9 thermostat cover gasket fit?\u003c\/strong\u003e The 18-2553-9 fits MCM\/MIE GM V-6 and V-8 marine engines that use the older style two-piece thermostat housing, including the 898 305 cid V-8 application built for 1983-1984.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow many gaskets come in a pack?\u003c\/strong\u003e Each Sierra 18-2553-9 package includes 2 thermostat cover gaskets, so you get a spare or enough for a two-sided housing in one purchase.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the 18-2553-9 gasket compatible with Mercruiser 27-47510?\u003c\/strong\u003e Yes, the Sierra 18-2553-9 thermostat cover gasket is interchangeable with Mercruiser 27-47510 and 27-47510Q, so it installs as a direct replacement for either of those OEM part numbers.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat other part numbers does this gasket cross-reference with?\u003c\/strong\u003e Besides the Mercruiser 27-47510 and 27-47510Q numbers, the 18-2553-9 also interchanges with GLM 31460, Mallory 9-60005, and Osco 47510.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs this an OEM or aftermarket gasket?\u003c\/strong\u003e The 18-2553-9 is a Sierra aftermarket gasket manufactured to meet or exceed the specifications of the original equipment part it replaces.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the 18-2553-9 gasket weigh?\u003c\/strong\u003e The Sierra 18-2553-9 thermostat cover gasket pack weighs 0.02 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhen should I replace my thermostat cover gasket?\u003c\/strong\u003e A thermostat cover gasket like the 18-2553-9 should be replaced any time the thermostat housing is removed for service, since reusing the old gasket can allow coolant to leak from the seal.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the 18-2553-9 work with the newer style thermostat housing?\u003c\/strong\u003e No, the 18-2553-9 is designed for the older style two-piece thermostat housing on MCM\/MIE GM V-6 and V-8 engines, not the newer housing designs.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is the UPC for the Sierra 18-2553-9 gasket?\u003c\/strong\u003e The Sierra 18-2553-9 thermostat cover gasket has UPC 808282162870.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan I use the 18-2553-9 gasket on a GM V-6 engine, not just V-8?\u003c\/strong\u003e Yes, the Sierra 18-2553-9 is listed to fit both GM V-6 and V-8 MCM\/MIE engines with the older two-piece thermostat housing.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988106981595,"sku":"SIE-18-2553-9","price":4.73,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-2553-9__38426.1737864401.500.750.jpg?v=1785188130"},{"product_id":"sierra-18-2546-9-thermostat-cover-gasket-replaces-johnson-evinrude-321184-fits-v-6-outboards-pack-of-2","title":"Sierra 18-2546-9 Thermostat Gasket for Johnson\/Evinrude V6 Outboard Engines, OEM 321184, Pack of 2","description":"\u003cp\u003eThe Sierra 18-2546-9 Thermostat Gasket seals the thermostat cover on Johnson\/Evinrude V6 outboard engines, preventing coolant leaks at the cover-to-housing joint so the cooling system maintains proper pressure and circulation. Each package contains two gaskets, giving you a spare on hand for the next service interval or a second engine. The gasket is molded from plastic and is designed as a direct fit for the thermostat cover assembly on applicable V6 outboards, correlating to OEM part number 321184.\u003c\/p\u003e\u003cp\u003eThis gasket is a wear item that should be replaced any time the thermostat cover is removed, whether during a thermostat replacement, cooling system inspection, or general engine service, since reusing a compressed or hardened gasket can allow coolant to seep past the cover and lead to overheating or reduced coolant flow. Installation is straightforward: remove the thermostat cover, clean the mating surfaces of old gasket material, position the new 18-2546-9 gasket, and reinstall the cover per the engine's service procedure. Sierra manufactures this part to meet or exceed the specifications of the original equipment part it replaces, making it a reliable choice for engine owners and marine service shops maintaining Johnson\/Evinrude V6 outboards.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-2546-9\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Type:\u003c\/strong\u003e Thermostat Cover Gasket\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePackage Quantity:\u003c\/strong\u003e 2 gaskets per pack\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMaterial:\u003c\/strong\u003e Plastic\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eColor:\u003c\/strong\u003e No Color\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eEngine Compatibility:\u003c\/strong\u003e Johnson\/Evinrude V6 outboard engines\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOEM Cross Reference:\u003c\/strong\u003e 321184\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 808282162818\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.03 pounds\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\u003cli\u003eJohnson\/Evinrude V6 outboard engines\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\u003cli\u003e321184\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat does the Sierra 18-2546-9 gasket fit?\u003c\/strong\u003e The Sierra 18-2546-9 is designed for the thermostat cover on Johnson\/Evinrude V6 outboard engines.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow many gaskets come in a pack?\u003c\/strong\u003e Each package of the Sierra 18-2546-9 contains two thermostat cover gaskets.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the 18-2546-9 gasket the same as OEM part 321184?\u003c\/strong\u003e Yes, the Sierra 18-2546-9 corresponds to OEM part number 321184 and is built to meet or exceed the original equipment specification.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat material is the thermostat gasket made from?\u003c\/strong\u003e The 18-2546-9 gasket is made of plastic, matching the material used for the original thermostat cover gasket.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhen should I replace this gasket?\u003c\/strong\u003e Replace the 18-2546-9 gasket any time the thermostat cover is removed, such as during a thermostat swap or cooling system service, since a reused gasket can leak coolant.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the gasket weigh?\u003c\/strong\u003e The Sierra 18-2546-9 thermostat gasket pack weighs 0.03 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs this a genuine Sierra part or an aftermarket copy?\u003c\/strong\u003e The 18-2546-9 is a genuine Sierra part manufactured to meet or exceed the specification of the original equipment part it replaces.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDo I need any other parts to complete a thermostat cover reseal?\u003c\/strong\u003e The 18-2546-9 package supplies the two thermostat cover gaskets; the thermostat itself and other cover hardware are separate parts not included in this package.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat color is the gasket?\u003c\/strong\u003e The Sierra 18-2546-9 gasket has no distinct color, consistent with its plastic construction.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs installation of the 18-2546-9 gasket difficult?\u003c\/strong\u003e No special tools are needed; installation involves removing the thermostat cover, cleaning the mating surfaces, and fitting the new 18-2546-9 gasket before reinstalling the cover.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988107047131,"sku":"SIE-18-2546-9","price":2.95,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-2546-9__83944.1722367523.500.750.jpg?v=1785188339"},{"product_id":"sierra-18-2554-9-thermostat-cover-gasket-2-pack-replaces-mercruiser-27-41812-fits-mercruiser-gm-v-6-v-8","title":"Sierra Thermostat Cover Gasket 18-2554-9, Replaces 27-41812, Fits MCM\/MIE GM V-6 \u0026 V-8 Engines - Pack of 2","description":"\u003cp\u003eThe Sierra 18-2554-9 Thermostat Cover Gasket seals the thermostat housing on MCM\/MIE GM V-6 \u0026amp; V-8 marine engines, preventing coolant leaks at this common failure point. Each package contains two gaskets, giving boat owners a spare for the next service interval or enough material to service two engines in one job. This gasket is a direct fit replacement for the OEM thermostat cover gasket used on these engine families, restoring a proper seal without modification.\u003c\/p\u003e\u003cp\u003eInstalling a fresh thermostat cover gasket during any thermostat replacement, cooling system inspection, or routine maintenance helps prevent coolant seepage that can lead to overheating or corrosion around the housing. Because the part is sold in a pack of two, it supports both immediate repair needs and future maintenance planning.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-2554-9\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Type:\u003c\/strong\u003e Thermostat Cover Gasket\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePackage Quantity:\u003c\/strong\u003e 2 gaskets per pack\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eEngine Fitment:\u003c\/strong\u003e MCM\/MIE GM V-6 \u0026amp; V-8 engines\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.08 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOEM Cross Reference:\u003c\/strong\u003e 27-41812, 27-90556, 27-41812Q\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 808282162887\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\u003cli\u003eMCM\/MIE GM V-6 \u0026amp; V-8 engines\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e27-41812\u003c\/li\u003e\n\u003cli\u003e27-90556\u003c\/li\u003e\n\u003cli\u003e27-41812Q\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat engines does the 18-2554-9 thermostat cover gasket fit?\u003c\/strong\u003e The Sierra 18-2554-9 is designed for MCM\/MIE GM V-6 \u0026amp; V-8 marine engines.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow many gaskets come in a pack?\u003c\/strong\u003e Each 18-2554-9 package includes 2 thermostat cover gaskets, enough for a repair with a spare or for servicing two engines.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhich OEM part numbers does this gasket replace?\u003c\/strong\u003e It replaces OEM numbers 27-41812, 27-90556, and 27-41812Q on MCM\/MIE GM V-6 \u0026amp; V-8 engines.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-2554-9 a genuine OEM part or an aftermarket equivalent?\u003c\/strong\u003e It is an aftermarket gasket manufactured by Sierra to match the fit and function of the OEM thermostat cover gasket it replaces.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the gasket weigh?\u003c\/strong\u003e The 18-2554-9 thermostat cover gasket weighs 0.08 pounds per pack.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhen should I replace the thermostat cover gasket?\u003c\/strong\u003e Replace the 18-2554-9 gasket any time the thermostat cover is removed, such as during thermostat replacement or if coolant seepage is noticed at the housing.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes this gasket fit both port and starboard engines?\u003c\/strong\u003e The 18-2554-9 is not side-specific; it fits MCM\/MIE GM V-6 \u0026amp; V-8 engines generally, based on engine family rather than mounting side.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is the difference between 18-2554-9 and 18-2555-9?\u003c\/strong\u003e 18-2554-9 is the thermostat gasket for GM V-6 \u0026amp; V-8 engines, while 18-2555-9 is a separate Sierra part number for 4-cylinder engine applications; make sure to order the number matching your engine.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan I use one gasket from the pack and save the other?\u003c\/strong\u003e Yes, the 18-2554-9 is sold as a pack of 2, so one gasket can be installed now and the second kept as a spare for a future service.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is included with the 18-2554-9 purchase?\u003c\/strong\u003e The package contains 2 Sierra thermostat cover gaskets; no thermostat or additional hardware is included.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988107079899,"sku":"SIE-18-2554-9","price":12.21,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-2554-9__36089.1732158012.500.750.jpg?v=1785188831"},{"product_id":"sierra-18-2733-water-shutter-for-mercruiser-stern-drive-replaces-92802-pkg-of-2","title":"Sierra 18-2733 Water Shutter, Replaces 92802 and 99370A2, Package of 2","description":"\u003cp\u003eThe Sierra 18-2733 is a marine water shutter designed for stern drive cooling systems, sold as a package of 2. Water shutters regulate raw water flow through the exhaust and cooling passages, helping maintain proper engine operating temperature and preventing exhaust water from backing up into the engine when it is not running. This part is built to meet or exceed the specifications of the original equipment it replaces, making it a direct, reliable substitute for worn or failed shutters.\u003c\/p\u003e\u003cp\u003eMeasuring 3.175 inches in length and 2.5 inches in width, the 18-2733 is manufactured under the Sierra brand for durability in continuous exposure to raw water and marine exhaust conditions. It replaces OEM numbers 92802 and 99370A2, so it fits applications originally equipped with either of those parts. Because it ships as a package of 2 and is priced per package, buyers replacing shutters in pairs can source both from a single part number.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-2733\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eLength:\u003c\/strong\u003e 3.175 inches\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWidth:\u003c\/strong\u003e 2.5 inches\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.14 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePackage Quantity:\u003c\/strong\u003e 2 (priced per package)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 808282124670\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\u003cli\u003eFits applications originally equipped with OEM water shutter 92802 or 99370A2\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e92802\u003c\/li\u003e\n\u003cli\u003e99370A2\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat does the Sierra 18-2733 water shutter do?\u003c\/strong\u003e It regulates raw water flow through a stern drive's cooling and exhaust passages, helping the engine reach and hold proper operating temperature and limiting water backing up into the exhaust when the engine is off.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow many shutters come in a package of the 18-2733?\u003c\/strong\u003e The 18-2733 is sold as a package of 2 and is priced per package, not per individual shutter.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat OEM part numbers does the Sierra 18-2733 replace?\u003c\/strong\u003e It replaces OEM numbers 92802 and 99370A2, so either of those part numbers can be cross-referenced to the 18-2733.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat are the dimensions of the 18-2733 water shutter?\u003c\/strong\u003e It measures 3.175 inches in length and 2.5 inches in width.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the Sierra 18-2733 weigh?\u003c\/strong\u003e Each package weighs 0.14 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-2733 an OEM part or an aftermarket replacement?\u003c\/strong\u003e The 18-2733 is a Sierra-brand replacement part engineered to meet or exceed the specifications of the original equipment water shutter it replaces (92802 or 99370A2).\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWill the 18-2733 fit any boat with a water shutter?\u003c\/strong\u003e It is a direct replacement only for applications that originally used OEM water shutter 92802 or 99370A2; confirm your original part number before ordering.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is included when I order the Sierra 18-2733?\u003c\/strong\u003e One package containing 2 water shutters (Sierra part number 18-2733) is included.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is the UPC for the Sierra 18-2733 water shutter?\u003c\/strong\u003e The UPC is 808282124670.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan I order a single water shutter instead of a pair?\u003c\/strong\u003e No, the Sierra 18-2733 is packaged and priced as a set of 2 shutters.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988109603035,"sku":"SIE-18-2733","price":26.96,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-2733_lg__12501.1558123391.500.750.jpg?v=1785188495"},{"product_id":"sierra-18-2732-9-water-shutter-for-mercruiser-stern-drives-replaces-oem-60930-pack-of-2","title":"Sierra 18-2732-9 Water Shutter, Replaces 60930, for Mercruiser Stern Drives - Pack of 2","description":"\u003cp\u003eThe Sierra 18-2732-9 Water Shutter is a metal water shutter designed for use with Mercruiser stern drives, sold as a pack of two so both shutters can be replaced together. Water shutters mount in the drive's water intake path and regulate cooling water flow, an important wear item to inspect and replace when servicing a stern drive's cooling system. Each shutter measures 6.125 inches in length by 2.360 inches in width and is finished in black metal construction built to hold up in the marine cooling environment.\u003c\/p\u003e\u003cp\u003eThis part is manufactured to meet or exceed the original equipment part it replaces, giving boat owners a direct, reliable replacement option when the original shutter has worn out or is no longer available. Because it ships as a pack of two, it is well suited to servicing both shutters in a stern drive at the same time rather than ordering single units separately.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-2732-9\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Type:\u003c\/strong\u003e Water Shutter\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePackage Quantity:\u003c\/strong\u003e 2 water shutters per package\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eLength:\u003c\/strong\u003e 6.125 inches\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWidth:\u003c\/strong\u003e 2.360 inches\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMaterial:\u003c\/strong\u003e Metal\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eColor:\u003c\/strong\u003e Black\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.14 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 808282166823\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eApplication:\u003c\/strong\u003e Mercruiser stern drives\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOEM Cross Reference:\u003c\/strong\u003e 60930\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cp\u003eDesigned for use with Mercruiser stern drives.\u003c\/p\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\u003cli\u003e60930\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat does the Sierra 18-2732-9 water shutter fit?\u003c\/strong\u003e The Sierra 18-2732-9 water shutter is designed for use with Mercruiser stern drives.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat OEM part number does the 18-2732-9 replace?\u003c\/strong\u003e It replaces OEM part number 60930, so it can be ordered as a direct replacement for that original part.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow many water shutters come in this package?\u003c\/strong\u003e This listing is for a pack of 2 water shutters, part number 18-2732-9, so both units in a stern drive can be replaced at once.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat material is the 18-2732-9 water shutter made of?\u003c\/strong\u003e It is made of metal, finished in black, for durability in the marine cooling environment.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat are the dimensions of the Sierra 18-2732-9 water shutter?\u003c\/strong\u003e Each shutter measures 6.125 inches in length by 2.360 inches in width.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the Sierra 18-2732-9 water shutter weigh?\u003c\/strong\u003e The 18-2732-9 water shutter weighs 0.14 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-2732-9 a genuine OEM part or an aftermarket replacement?\u003c\/strong\u003e It is a Sierra aftermarket replacement manufactured to meet or exceed the original equipment part it replaces, part number 60930.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan the 18-2732-9 be used to replace just one shutter, or must both be replaced?\u003c\/strong\u003e The 18-2732-9 is sold as a pack of 2, so while both are included, buyers servicing only one shutter can retain the extra unit for a future replacement.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is the UPC for the Sierra 18-2732-9 water shutter pack?\u003c\/strong\u003e The UPC for the Sierra 18-2732-9 two-pack water shutter is 808282166823.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the Sierra 18-2732-9 water shutter work with inboard engines?\u003c\/strong\u003e No, the 18-2732-9 water shutter is designed for use with Mercruiser stern drives, not inboard engines.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow do I know if my Mercruiser stern drive needs a new water shutter?\u003c\/strong\u003e A worn or damaged water shutter can affect cooling water flow in a Mercruiser stern drive; if the original shutter matching OEM number 60930 is worn, the Sierra 18-2732-9 is a direct replacement.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988109701339,"sku":"SIE-18-2732-9","price":73.61,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/Untitled-1__13204.1771533092.500.750.jpg?v=1785188147"},{"product_id":"thermostat-cover-gasket-for-mercruiser-4-cylinder-engines-replaces-27-896561-27-89656-sierra-18-2831-9-pack-of-2","title":"Sierra 18-2831-9 Thermostat Cover Gasket, Replaces 27-475901 and 27-47590, 4 Cylinder Engines, Pack of 2","description":"\u003cp\u003eThe Sierra 18-2831-9 Thermostat Cover Gasket seals the thermostat housing on 4 cylinder marine engines, preventing coolant leaks at the thermostat cover joint. Each package contains 2 gaskets, so a spare is on hand for a future service or so both sides of a twin-engine boat can be serviced from a single purchase. The gasket is manufactured by Sierra to replace OEM part numbers 27-475901 and 27-47590, giving boat owners a direct-fit option for thermostat housing service without sourcing the original equipment part. Sierra parts are built to meet or exceed the specifications of the original equipment they replace, making this gasket a straightforward choice when doing a thermostat swap, a cooling system inspection, or general engine maintenance. Because a worn or damaged thermostat cover gasket is a common source of small coolant leaks and overheating complaints, keeping a correct-fit gasket like the 18-2831-9 on hand simplifies routine thermostat service. This is a lightweight, low-cost component but proper fit and sealing are essential to keeping the cooling system airtight and leak-free.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-2831-9\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Type:\u003c\/strong\u003e Thermostat Cover Gasket\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePackage Quantity:\u003c\/strong\u003e Pack of 2\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eEngine Fitment:\u003c\/strong\u003e 4 Cylinder\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOEM Cross Reference:\u003c\/strong\u003e 27-475901, 27-47590\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 808282163389\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eGTIN:\u003c\/strong\u003e 00808282163389\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.03 pounds\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\u003cli\u003e4 Cylinder engines\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e27-475901\u003c\/li\u003e\n\u003cli\u003e27-47590\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat does the Sierra 18-2831-9 gasket fit?\u003c\/strong\u003e The Sierra 18-2831-9 Thermostat Cover Gasket is designed for 4 cylinder marine engines and seals the thermostat housing cover.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow many gaskets come in a package?\u003c\/strong\u003e Part number 18-2831-9 is sold in a package of 2 gaskets, giving you a spare for a future thermostat service.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat OEM part numbers does this gasket replace?\u003c\/strong\u003e It replaces OEM numbers 27-475901 and 27-47590, so either of those part numbers can be cross-referenced to the Sierra 18-2831-9.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-2831-9 a genuine OEM part or an aftermarket replacement?\u003c\/strong\u003e It is a Sierra-manufactured aftermarket gasket built to meet or exceed the specifications of the original 27-475901 and 27-47590 OEM parts it replaces.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the gasket weigh?\u003c\/strong\u003e Each package of the 18-2831-9 Thermostat Cover Gasket weighs 0.03 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhen should the thermostat cover gasket be replaced?\u003c\/strong\u003e Replace the gasket whenever the thermostat housing is opened for service or if coolant seepage is visible at the thermostat cover joint; the 18-2831-9 is sized for that resealing job on 4 cylinder engines.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan I use one gasket from the pack and save the other?\u003c\/strong\u003e Yes, the 18-2831-9 is sold as a pack of 2, so one gasket can be installed now and the second kept as a spare for the next service.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the 18-2831-9 gasket require any sealant to install?\u003c\/strong\u003e The dossier does not specify a sealant requirement for the 18-2831-9; follow your engine's thermostat housing service procedure when installing.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs this the same gasket used on 6 cylinder engines?\u003c\/strong\u003e No, the Sierra 18-2831-9 is specified for 4 cylinder engines; a different Sierra part number covers 4 and 6 cylinder applications with a different OEM cross-reference.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is the UPC for the Sierra 18-2831-9?\u003c\/strong\u003e The UPC for this thermostat cover gasket package is 808282163389.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988131131611,"sku":"SIE-18-2831-9","price":3.71,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-2831-9__61405.1737845920.500.750.jpg?v=1785188391"},{"product_id":"sierra-18-2917-9-thermostat-gasket-for-mercruiser-gm-v-6-v-8-replaces-27-53045-pack-of-2","title":"Sierra 18-2917-9 Thermostat Housing Gasket - Pack of 2 for MerCruiser MCM\/MIE GM V-6 \u0026 V-8 Engines","description":"\u003cp\u003eThe Sierra 18-2917-9 is a thermostat housing gasket for marine inboard engines, sold as a pack of 2 so you have a spare or can service both the thermostat housing and a related joint in the same job. It is designed to seal the thermostat housing against the cylinder head or manifold, preventing coolant loss and maintaining proper engine operating temperature. The gasket has a round profile sized to match the thermostat housing bore and bolt pattern on the engines it is built for.\u003c\/p\u003e\u003cp\u003eThis gasket fits MCM\/MIE GM V-6 and V-8 marine engines. It is specifically listed for 5.7L MIE engines, including engine model F622100 (serial number 0K999999) and engine model L002003 and up, where it is used alongside companion gasket part numbers 18-3647 and 18-3649 in the thermostat housing assembly. Replacing a worn or hardened thermostat housing gasket is a routine part of cooling system maintenance and is typically done any time the thermostat housing is removed for inspection, cleaning, or thermostat replacement, to ensure a leak-free reseal.\u003c\/p\u003e\u003cp\u003eSold under Sierra's marine engine parts line, this gasket is identified by UPC 808282164195 and is built to be a direct fit for the engines and thermostat housings listed above.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-2917-9\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Type:\u003c\/strong\u003e Thermostat Housing Gasket\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePack Quantity:\u003c\/strong\u003e 2\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eShape:\u003c\/strong\u003e Round\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMaterial:\u003c\/strong\u003e Other\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.02 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 808282164195\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eGTIN:\u003c\/strong\u003e 00808282164195\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFits:\u003c\/strong\u003e MCM\/MIE GM V-6 and V-8 engines\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e5.7L MIE, engine model F622100, serial number 0K999999\u003c\/li\u003e\n\u003cli\u003e5.7L MIE, engine model L002003 and up\u003c\/li\u003e\n\u003cli\u003eMCM\/MIE GM V-6 and V-8 engines\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat engines does the Sierra 18-2917-9 thermostat gasket fit?\u003c\/strong\u003e The 18-2917-9 fits MCM\/MIE GM V-6 and V-8 marine engines, and is specifically listed for 5.7L MIE engines under engine model F622100 (serial number 0K999999) and engine model L002003 and up.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow many gaskets come in one package?\u003c\/strong\u003e Sierra part 18-2917-9 is sold as a pack of 2 thermostat housing gaskets, giving you enough for the job plus a spare.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is the shape of this gasket?\u003c\/strong\u003e This thermostat housing gasket is round in shape, matching the profile of the thermostat housing bore it seals.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the 18-2917-9 gasket weigh?\u003c\/strong\u003e Each package of the Sierra 18-2917-9 thermostat gasket weighs 0.02 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs this gasket a genuine Sierra part?\u003c\/strong\u003e Yes, part number 18-2917-9 is a Sierra branded thermostat housing gasket, not a generic substitute.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat other parts are used with the 18-2917-9 gasket in the thermostat housing assembly?\u003c\/strong\u003e On 5.7L MIE engines, the 18-2917-9 gasket is used together with companion gasket part numbers 18-3647 and 18-3649 in the thermostat housing assembly.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the UPC on this gasket match the packaging I should expect?\u003c\/strong\u003e Yes, the Sierra 18-2917-9 thermostat gasket carries UPC 808282164195, which you can check against the packaging to confirm you have the correct part.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhen should I replace the thermostat housing gasket?\u003c\/strong\u003e The 18-2917-9 gasket should be replaced any time the thermostat housing is removed, such as during thermostat replacement or cooling system service, since a used gasket will not reseal reliably.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWill this gasket fit non-MIE MerCruiser engines?\u003c\/strong\u003e The 18-2917-9 is listed for MCM\/MIE GM V-6 and V-8 engines, with confirmed fitment on 5.7L MIE models F622100 and L002003 and up; fitment outside of those engines is not specified.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat material is the 18-2917-9 gasket made from?\u003c\/strong\u003e The material for the Sierra 18-2917-9 thermostat gasket is listed simply as Other, without a more specific composition given by the manufacturer.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988133195995,"sku":"SIE-18-2917-9","price":6.87,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-2917-9__30131.1737884303.500.750.jpg?v=1785188577"},{"product_id":"marine-thermostat-140f-for-evinrude-johnson-3-cylinder-90-degree-looper-outboards-replaces-omc-394409-434137-sierra-18-3500","title":"Sierra 18-3500 Thermostat, 140 Degree F, Replaces 437090, Fits Evinrude E115\/E135\/E150\/E175 Outboards","description":"\u003cp\u003eThe Sierra 18-3500 is a 140 degree F thermostat built for Evinrude outboard engines, regulating engine cooling water flow to keep the powerhead operating within its designed temperature range. Maintaining the correct opening temperature protects the engine from the damage caused by running too hot or too cold, and a worn or stuck thermostat is a common cause of overheating alarms and inconsistent engine temperatures. This thermostat is constructed of metal for durability in the marine cooling system environment and is engineered to meet or exceed the performance of the original equipment part it replaces.\u003c\/p\u003e\u003cp\u003eThe 18-3500 is a direct fit for specific Evinrude outboard models and years as listed below, and it cross-references to OEM part number 437090, making it a straightforward like-for-like replacement during routine cooling system maintenance or when troubleshooting an overheating condition.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-3500\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Type:\u003c\/strong\u003e Thermostat\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTemperature Rating:\u003c\/strong\u003e 140 degrees F\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMaterial:\u003c\/strong\u003e Metal\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.05 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 808282159689\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eReplaces (OEM):\u003c\/strong\u003e 437090\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFitment:\u003c\/strong\u003e Evinrude E115 (1997); Evinrude E135, E150, E175 (2000-06)\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eEvinrude E115 (1997)\u003c\/li\u003e\n\u003cli\u003eEvinrude E135, E150, E175 (2000-06)\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\u003cli\u003e437090\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat temperature rating is the Sierra 18-3500 thermostat?\u003c\/strong\u003e The Sierra 18-3500 is a 140 degree F thermostat, meaning it begins to open at that temperature to regulate engine cooling water flow.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhich Evinrude outboards does the 18-3500 thermostat fit?\u003c\/strong\u003e It fits the Evinrude E115 (1997 model year) and the Evinrude E135, E150, and E175 (2000-06 model years).\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the Sierra 18-3500 replace OEM part 437090?\u003c\/strong\u003e Yes, the 18-3500 is a direct cross-reference to OEM part number 437090.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is the 18-3500 thermostat made of?\u003c\/strong\u003e It is made of metal, providing durability for use in the marine engine cooling system.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the Sierra 18-3500 thermostat weigh?\u003c\/strong\u003e It weighs 0.05 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-3500 a genuine OEM part or an aftermarket replacement?\u003c\/strong\u003e It is a Sierra-manufactured replacement thermostat engineered to meet or exceed the performance of the original 437090 part it replaces, not a repackaged OEM component.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWill a stuck or worn thermostat cause my outboard to overheat?\u003c\/strong\u003e Yes, a failed thermostat is a common cause of overheating alarms and inconsistent running temperature, which is why replacing it with a correctly rated part like the 18-3500 is important.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the 18-3500 fit engines outside the listed Evinrude E115\/E135\/E150\/E175 range?\u003c\/strong\u003e Fitment for the 18-3500 is confirmed for the Evinrude E115 (1997) and E135, E150, E175 (2000-06); it should not be assumed to fit other models or years.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is included when I order the 18-3500?\u003c\/strong\u003e The order includes one Sierra 18-3500 140 degree F thermostat.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat UPC does the Sierra 18-3500 thermostat use?\u003c\/strong\u003e The UPC for this thermostat is 808282159689.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan I identify the correct replacement thermostat by the OEM number 437090?\u003c\/strong\u003e Yes, OEM number 437090 cross-references directly to the Sierra 18-3500 thermostat.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988149612763,"sku":"SIE-18-3500","price":27.64,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/18-3500__00571.1737875979.500.750.jpg?v=1785188170"},{"product_id":"thermostat-housing-for-mercruiser-gm-v6-v8-305-350-454-502-cid-closed-cooling-systems-replaces-807074a1-sierra-18-3531","title":"Sierra Thermostat Housing 18-3531 for 7.4L 454 V-8 MIE Closed Cooling Engines, 1996-1997","description":"\u003cp\u003eThe Sierra 18-3531 is a marine engine thermostat housing built to fit MerCruiser 7.4L EFI MIE 454 cubic inch V-8 engines equipped with closed (freshwater) cooling, model years 1996-1997, within the serial number range F874815 to K999999. The thermostat housing is the component that bolts to the engine and holds the thermostat in place, sealing the coolant circuit so the engine's cooling system can regulate operating temperature correctly. Replacing a cracked, corroded, or leaking thermostat housing with a properly fitted unit like the 18-3531 helps prevent coolant loss and overheating on engines running a closed cooling setup.\u003c\/p\u003e\u003cp\u003eThis housing is sold as a standalone replacement part for the applications listed above. Always confirm your engine's model year and serial number fall within the listed range before ordering, since MerCruiser 7.4L applications changed housing part numbers across different cooling configurations and production runs.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-3531\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Type:\u003c\/strong\u003e Thermostat Housing\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 1.41 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eEngine Application:\u003c\/strong\u003e 7.4L EFI MIE 454\/V-8\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCooling System:\u003c\/strong\u003e Closed Cooling (Freshwater Cooling)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eModel Years:\u003c\/strong\u003e 1996-1997\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSerial Number Range:\u003c\/strong\u003e F874815 to K999999\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 808282183189\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\u003cli\u003eMerCruiser 7.4L EFI MIE 454\/V-8, Closed Cooling (FWC), model years 1996-1997, serial numbers F874815 to K999999\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat engines does the Sierra 18-3531 thermostat housing fit?\u003c\/strong\u003e The 18-3531 fits MerCruiser 7.4L EFI MIE 454 cubic inch V-8 engines with closed (freshwater) cooling, model years 1996-1997, within serial number range F874815 to K999999.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the 18-3531 work on standard cooling 7.4L engines?\u003c\/strong\u003e No, the 18-3531 is designated for closed (freshwater) cooling 7.4L EFI MIE 454\/V-8 engines specifically; a different housing part number applies to standard cooling versions of the 7.4L MIE engine.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the 18-3531 thermostat housing weigh?\u003c\/strong\u003e The Sierra 18-3531 thermostat housing weighs 1.41 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow do I know if my engine's serial number is in range for this housing?\u003c\/strong\u003e The 18-3531 covers MerCruiser 7.4L EFI MIE FWC 454\/V-8 engines with serial numbers between F874815 and K999999; check your engine's serial tag against that range before ordering.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the 18-3531 a genuine Sierra part?\u003c\/strong\u003e Yes, 18-3531 is the Sierra manufacturer part number for this thermostat housing, not a generic or unbranded substitute.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat model years does the 18-3531 cover?\u003c\/strong\u003e This housing is specified for 1996-1997 model year MerCruiser 7.4L EFI MIE FWC 454\/V-8 engines.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is included with the 18-3531?\u003c\/strong\u003e The 18-3531 is sold as a standalone thermostat housing; it does not include the thermostat itself unless otherwise noted at purchase.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhy replace a thermostat housing instead of just the thermostat?\u003c\/strong\u003e If the housing itself is cracked, corroded, or no longer sealing properly, replacing just the thermostat will not stop coolant leaks or overheating; the 18-3531 replaces the housing component that seals the coolant circuit.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the UPC for the 18-3531 thermostat housing 808282183189?\u003c\/strong\u003e Yes, the Sierra 18-3531 thermostat housing carries UPC 808282183189.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan the 18-3531 be used on a 7.4L MIE engine without closed cooling?\u003c\/strong\u003e No; the 18-3531 is built for the closed (freshwater) cooling configuration of the 7.4L EFI MIE 454\/V-8, so it should not be used on a standard raw-water cooled version of that engine.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988150759643,"sku":"SIE-18-3531","price":18.37,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/18-3531__11789.1737885550.500.750.jpg?v=1785188238"},{"product_id":"marine-thermostat-130f-for-mercury-mariner-200-225-250-3-0l-efi-dfi-outboards-replaces-mercury-885599004-sierra-18-3535","title":"Sierra 18-3535 Thermostat 130F, Replaces Mercury 885599004, Fits Mercury\/Mariner 200\/225\/250 HP Outboards","description":"\u003cp\u003eThe Sierra 18-3535 is a 130 degree F (54 degree C) thermostat built for Mercury\/Mariner outboard engines. It regulates coolant flow through the engine's cooling system, opening at its rated temperature to help the engine reach and hold proper operating temperature. The housing is white with a digital, no-backlight display and push-button\/touch control.\u003c\/p\u003e\u003cp\u003eThis thermostat is a direct replacement for Mercury Marine OEM part 885599004 and is engineered to meet or exceed the original equipment part it replaces. It fits a range of Mercury\/Mariner 3.0L DFI DTS and 3.0L EFI outboards spanning the 200, 225, and 250 horsepower lines, including the SeaPro and 250 Long EFI variants, as identified by their serial number breakpoints below. Each unit weighs 0.09 pounds.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-3535\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Type:\u003c\/strong\u003e Thermostat\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTemperature Rating:\u003c\/strong\u003e 130 degrees F (54 degrees C)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eReplaces (OEM):\u003c\/strong\u003e 885599004\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eColor:\u003c\/strong\u003e White\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDisplay Type:\u003c\/strong\u003e Digital, no backlight\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eControl Type:\u003c\/strong\u003e Push-button\/touch control\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.09 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 808282241216\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFitment:\u003c\/strong\u003e Mercury\/Mariner outboards: 200 3.0L DFI DTS (ALL), 200 3.0L EFI (2003 \u0026amp; Up)(OT750164 \u0026amp; Up), 200 DFI (1997 \u0026amp; Up)(OG386496 \u0026amp; Up), 225 3.0L EFI (1999 \u0026amp; Up)(OG760300 \u0026amp; Up), 225 3.0L EFI SeaPro (2004 \u0026amp; Up)(OT801000 \u0026amp; Up), 225 3.0L DFI DTS (2003 \u0026amp; Up)(OT599000 \u0026amp; Up), 225 DFI (1998 \u0026amp; Up)(OG590000 \u0026amp; Up), 250 3.0L EFI (1999 \u0026amp; Up)(OG760300 \u0026amp; Up), 250 Long 3.0L EFI (OT861319 \u0026amp; Up)\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eMercury\/Mariner 200 3.0L DFI DTS (ALL)\u003c\/li\u003e\n\u003cli\u003eMercury\/Mariner 200 3.0L EFI (2003 \u0026amp; Up)(OT750164 \u0026amp; Up)\u003c\/li\u003e\n\u003cli\u003eMercury\/Mariner 200 DFI (1997 \u0026amp; Up)(OG386496 \u0026amp; Up)\u003c\/li\u003e\n\u003cli\u003eMercury\/Mariner 225 3.0L EFI (1999 \u0026amp; Up)(OG760300 \u0026amp; Up)\u003c\/li\u003e\n\u003cli\u003eMercury\/Mariner 225 3.0L EFI SeaPro (2004 \u0026amp; Up)(OT801000 \u0026amp; Up)\u003c\/li\u003e\n\u003cli\u003eMercury\/Mariner 225 3.0L DFI DTS (2003 \u0026amp; Up)(OT599000 \u0026amp; Up)\u003c\/li\u003e\n\u003cli\u003eMercury\/Mariner 225 DFI (1998 \u0026amp; Up)(OG590000 \u0026amp; Up)\u003c\/li\u003e\n\u003cli\u003eMercury\/Mariner 250 3.0L EFI (1999 \u0026amp; Up)(OG760300 \u0026amp; Up)\u003c\/li\u003e\n\u003cli\u003eMercury\/Mariner 250 Long 3.0L EFI (OT861319 \u0026amp; Up)\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\u003cli\u003e885599004\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat temperature does the Sierra 18-3535 thermostat open at?\u003c\/strong\u003e 130 degrees F (54 degrees C) is the rated opening temperature of the Sierra 18-3535 thermostat, which controls coolant flow in Mercury\/Mariner outboard engines.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhich Mercury\/Mariner outboards does part number 18-3535 fit?\u003c\/strong\u003e The Sierra 18-3535 fits Mercury\/Mariner 200 3.0L DFI DTS (ALL), 200 3.0L EFI (2003 \u0026amp; Up, OT750164 \u0026amp; Up), 200 DFI (1997 \u0026amp; Up, OG386496 \u0026amp; Up), 225 3.0L EFI (1999 \u0026amp; Up), 225 3.0L EFI SeaPro (2004 \u0026amp; Up), 225 3.0L DFI DTS (2003 \u0026amp; Up), 225 DFI (1998 \u0026amp; Up), 250 3.0L EFI (1999 \u0026amp; Up), and 250 Long 3.0L EFI (OT861319 \u0026amp; Up).\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the 18-3535 a direct replacement for Mercury 885599004?\u003c\/strong\u003e Yes, Sierra 18-3535 directly replaces Mercury Marine OEM part 885599004.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the Sierra 18-3535 thermostat weigh?\u003c\/strong\u003e 0.09 pounds is the weight of the Sierra 18-3535 thermostat.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat color is the Sierra 18-3535 thermostat housing?\u003c\/strong\u003e White is the housing color of the Sierra 18-3535 thermostat.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is included when I order the 18-3535?\u003c\/strong\u003e One Sierra 18-3535 thermostat is included per unit.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-3535 an OEM or aftermarket part?\u003c\/strong\u003e Sierra 18-3535 is an aftermarket thermostat engineered to meet or exceed the Mercury OEM part 885599004 that it replaces.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the 18-3535 have a digital display?\u003c\/strong\u003e Yes, a digital display with no backlight is built into the Sierra 18-3535 thermostat, along with push-button\/touch control.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWill the 18-3535 fit both the standard 250 EFI and the 250 Long EFI?\u003c\/strong\u003e Both are covered: the Sierra 18-3535 fits the Mercury\/Mariner 250 3.0L EFI (1999 \u0026amp; Up) as well as the 250 Long 3.0L EFI (OT861319 \u0026amp; Up).\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is the UPC for the Sierra 18-3535 thermostat?\u003c\/strong\u003e 808282241216 is the UPC assigned to the Sierra 18-3535 thermostat.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988150792411,"sku":"SIE-18-3535","price":89.35,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-3535_lg__21125.1558125835.500.750.jpg?v=1785188249"},{"product_id":"marine-thermostat-50c-for-yamaha-outboards-replaces-60v-12411-00-fits-f115-vz250-z300-sierra-18-3525","title":"Sierra Thermostat 18-3525 for Yamaha 2-Stroke Outboards VZ200, V225, VZ250","description":"\u003cp\u003eThe Sierra 18-3525 is a replacement cooling system thermostat engineered for Yamaha 2-stroke outboard engines. It regulates engine operating temperature by controlling coolant flow through the cooling system, helping the engine reach and maintain proper running temperature for efficient performance and long-term reliability. This thermostat is a direct application-specific part for the Yamaha VZ200 (2005-09), V225 (2003-09), and VZ250 (2003-09) outboards, and each of these engines requires two thermostats per engine for complete cooling system coverage.\u003c\/p\u003e\u003cp\u003eAs a cooling system wear item, the thermostat should be inspected and replaced as part of routine outboard maintenance or whenever overheating, erratic temperature gauge readings, or reduced engine performance point to a stuck or failing thermostat. Installing the correct application-specific thermostat is important, since Yamaha 2-stroke outboards use different Sierra thermostat part numbers depending on model and year.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-3525\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Type:\u003c\/strong\u003e Thermostat\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eEngine Type:\u003c\/strong\u003e Yamaha 2-Stroke Outboard\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eQuantity Per Engine:\u003c\/strong\u003e 2\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eColor:\u003c\/strong\u003e Copper\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.11 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 808282339364\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eYamaha VZ200, 2005-09\u003c\/li\u003e\n\u003cli\u003eYamaha V225, 2003-09\u003c\/li\u003e\n\u003cli\u003eYamaha VZ250, 2003-09\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\u003cli\u003eNo OEM cross-reference numbers listed for this part number.\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat does the Sierra 18-3525 thermostat do?\u003c\/strong\u003e It regulates coolant flow in the cooling system of a Yamaha 2-stroke outboard so the engine reaches and holds its proper operating temperature. Part number 18-3525 is the Sierra replacement thermostat for this application.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the Sierra 18-3525 fit a Yamaha VZ200 outboard?\u003c\/strong\u003e Yes, thermostat 18-3525 is the listed application for the Yamaha VZ200 covering model years 2005-09.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhich Yamaha outboard models use thermostat 18-3525?\u003c\/strong\u003e Thermostat 18-3525 applies to the Yamaha VZ200 (2005-09), V225 (2003-09), and VZ250 (2003-09).\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow many thermostats does my Yamaha 2-stroke outboard need?\u003c\/strong\u003e Two. The VZ200, V225, and VZ250 applications for the Sierra 18-3525 each require a quantity of 2 thermostats per engine.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs a gasket included with the Sierra 18-3525 thermostat?\u003c\/strong\u003e No separate gasket or thermostat kit number is listed for part 18-3525, so it is supplied as the thermostat only.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is the weight of the Sierra 18-3525 thermostat?\u003c\/strong\u003e It weighs 0.11 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWill 18-3525 fit a Yamaha V225 from 2003 to 2009?\u003c\/strong\u003e Yes, the V225 model years 2003-09 use thermostat 18-3525, with two units required per engine.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat years does the VZ250 application cover for part 18-3525?\u003c\/strong\u003e The Yamaha VZ250 application for thermostat 18-3525 covers model years 2003-09.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow is 18-3525 different from the Sierra 18-3540 thermostat?\u003c\/strong\u003e 18-3525 is the thermostat for the Yamaha VZ200 (2005-09), V225 (2003-09), and VZ250 (2003-09), while 18-3540 is a separate part number used on other Yamaha 200-250 hp applications and comes with its own matching gasket and kit numbers. The two are not interchangeable across applications.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-3525 a genuine Yamaha part or aftermarket?\u003c\/strong\u003e Sierra 18-3525 is an aftermarket replacement thermostat manufactured by Sierra for the specified Yamaha 2-stroke outboard applications.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow do I know if my outboard's thermostat needs replacing?\u003c\/strong\u003e Signs include engine overheating, erratic temperature gauge readings, or reduced cooling performance; on the applicable Yamaha VZ200, V225, or VZ250 outboards, the Sierra 18-3525 is the correct replacement thermostat to install.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988150857947,"sku":"SIE-18-3525","price":37.21,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-3525__30535.1655148687.500.750.jpg?v=1785188562"},{"product_id":"sierra-18-3536-marine-thermostat-143f-62c-replaces-mercury-833072003-fits-v135-v150-v175-dfi-2-5l-outboards","title":"Sierra 18-3536 Thermostat, 143 Degree F, Replaces Mercury Marine 833072","description":"\u003cp\u003eThe Sierra 18-3536 is a marine engine thermostat built for Mercury marine applications. It regulates engine coolant flow to maintain proper operating temperature, opening at a rated 143 degrees F (62 degrees C) to help the engine reach and hold optimal temperature for efficient combustion and long-term reliability. Consistent, accurate thermostat operation protects against overheating and against running too cool, both of which can reduce engine efficiency and accelerate wear.\u003c\/p\u003e\u003cp\u003eThis thermostat is a direct interchange for the original Mercury Marine part, so it installs using the same mounting configuration as the OEM unit it replaces. Sierra manufactures marine replacement parts to meet or exceed the specifications of the original equipment they replace, making the 18-3536 a straightforward swap when a Mercury thermostat has failed or is due for routine replacement.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-3536\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTemperature Rating:\u003c\/strong\u003e 143 degrees F (62 degrees C)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eColor:\u003c\/strong\u003e White\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.06 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 808282241230\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cp\u003eDesigned for use in Mercury marine applications.\u003c\/p\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eMercury Marine 833072\u003c\/li\u003e\n\u003cli\u003eMercury Marine 833072003\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat temperature does the Sierra 18-3536 thermostat open at?\u003c\/strong\u003e The Sierra 18-3536 is rated to open at 143 degrees F (62 degrees C), which is the temperature at which it begins allowing coolant to flow through the engine.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat does the Sierra 18-3536 replace?\u003c\/strong\u003e It is a direct interchange for Mercury Marine part numbers 833072 and 833072003.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-3536 an OEM or aftermarket part?\u003c\/strong\u003e It is an aftermarket replacement manufactured by Sierra to meet or exceed the specifications of the original Mercury Marine thermostat it replaces.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat color is the Sierra 18-3536 thermostat?\u003c\/strong\u003e The Sierra 18-3536 thermostat is white.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the Sierra 18-3536 thermostat weigh?\u003c\/strong\u003e This thermostat weighs 0.06 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat engine applications is the Sierra 18-3536 designed for?\u003c\/strong\u003e Sierra designed the 18-3536 thermostat for use in Mercury marine applications.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the Sierra 18-3536 come with a gasket or other components?\u003c\/strong\u003e The listing for the Sierra 18-3536 includes the thermostat itself; no additional components are specified.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow do I know if my Mercury thermostat needs replacing?\u003c\/strong\u003e Signs like engine overheating, slow warm-up, or erratic temperature gauge readings often indicate a failed thermostat; if your Mercury engine used part 833072 or 833072003, the Sierra 18-3536 is a direct replacement.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is the UPC for the Sierra 18-3536 thermostat?\u003c\/strong\u003e The UPC for the Sierra 18-3536 thermostat is 808282241230.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan I use the Sierra 18-3536 on any marine engine?\u003c\/strong\u003e The Sierra 18-3536 is designed specifically for Mercury marine applications that originally used thermostat 833072 or 833072003.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988150890715,"sku":"SIE-18-3536","price":34.35,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-3536_lg__11743.1558125898.500.750.jpg?v=1785188248"},{"product_id":"sierra-18-3539-marine-thermostat-kit-160f-replaces-volvo-penta-3831426-closed-cooling-system-includes-sealing-ring","title":"Sierra 18-3539 140 Degree Thermostat Kit for Closed Cooling Systems, Replaces 875779","description":"\u003cp\u003eThe Sierra 18-3539 is a 140 degree thermostat kit built for closed cooling systems, supplying a marine engine's cooling circuit with a factory-style thermostat that opens at the correct temperature to keep the engine running in its proper operating range. Running an engine without the correct thermostat, or with a unit that has failed open or closed, can lead to overheating or the engine never reaching efficient operating temperature, so replacing a worn or incorrect thermostat with the properly rated 140 degree unit is a routine but important part of closed cooling system maintenance.\u003c\/p\u003e\u003cp\u003eThis kit includes the sealing ring needed for installation, so the thermostat housing can be resealed at the same time the thermostat itself is replaced, reducing the chance of a coolant leak from an old or hardened gasket surface. The 18-3539 is designed as a direct replacement for engines that originally used a 140 degree thermostat in a closed cooling configuration.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-3539\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Type:\u003c\/strong\u003e Thermostat Kit\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTemperature Rating:\u003c\/strong\u003e 140 degrees\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSystem Type:\u003c\/strong\u003e Closed Cooling System\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eIncludes:\u003c\/strong\u003e Sealing ring\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Dimensions:\u003c\/strong\u003e 2.75 x 3.63 x 2.5 inches\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.2 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 808282265854\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\u003cli\u003eDesigned for closed cooling systems specifying a 140 degree thermostat\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\u003cli\u003e875779\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat temperature does the Sierra 18-3539 thermostat open at?\u003c\/strong\u003e The Sierra 18-3539 is rated at 140 degrees, meaning it opens at that temperature to regulate coolant flow in a closed cooling system.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes this kit include the sealing ring?\u003c\/strong\u003e Yes, the 18-3539 thermostat kit includes the sealing ring needed to reseal the thermostat housing during installation.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat OEM part numbers does the Sierra 18-3539 replace?\u003c\/strong\u003e The 18-3539 replaces OEM part number 875779.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the 18-3539 a complete kit or just the thermostat?\u003c\/strong\u003e It is a complete kit consisting of the 140 degree thermostat and a sealing ring, not just the thermostat alone.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat type of cooling system is the 18-3539 designed for?\u003c\/strong\u003e This thermostat kit is designed for closed cooling systems, where the correct 140 degree thermostat is required for proper temperature regulation.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the 18-3539 thermostat kit weigh?\u003c\/strong\u003e The Sierra 18-3539 weighs 0.2 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat are the dimensions of the 18-3539 thermostat kit?\u003c\/strong\u003e The kit measures 2.75 x 3.63 x 2.5 inches.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-3539 a genuine aftermarket replacement part?\u003c\/strong\u003e Yes, the 18-3539 is manufactured by Sierra as a direct replacement thermostat kit, cross-referenced to OEM number 875779.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhy does my engine need the correct thermostat temperature rating?\u003c\/strong\u003e Installing a thermostat with the wrong temperature rating, instead of the 140 degree unit specified for the 18-3539 application, can cause the engine to overheat or run below its proper operating temperature.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is the UPC for the Sierra 18-3539 thermostat kit?\u003c\/strong\u003e The UPC for the Sierra 18-3539 thermostat kit is 808282265854.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988150923483,"sku":"SIE-18-3539","price":46.19,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-3539_lg__11883.1558126069.500.750.jpg?v=1785189178"},{"product_id":"sierra-18-3543-marine-thermostat-143f-replaces-brp-omc-435491-for-evinrude-johnson-v-4-and-v-6-crossflow-outboards","title":"Sierra 18-3543 143 Degree Thermostat, Replaces BRP 435491, Fits 200-235 HP Outboards","description":"\u003cp\u003eThe Sierra 18-3543 is a 143 degree F thermostat engineered for marine outboard cooling systems, controlling engine operating temperature by regulating coolant flow once the engine reaches its target range. Maintaining the correct opening temperature protects the powerhead from overheating damage while allowing the engine to reach efficient operating temperature quickly, which supports fuel efficiency and reduces wear on internal components. The thermostat is built from plastic construction for corrosion resistance in a marine environment and is a direct equivalent for the BRP 435491 thermostat, making it a straightforward replacement during routine cooling system maintenance or when an OEM unit fails. It ships as a single unit ready for installation in place of the original thermostat. This part is applicable to 200 HP outboards from 1977-83 and 235 HP outboards from 1978-85. Boat owners performing scheduled maintenance, addressing an overheating alarm, or replacing a stuck or failed thermostat can use the Sierra 18-3543 as a reliable OEM-equivalent part backed by the Sierra brand, a longstanding supplier of marine engine parts.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-3543\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Type:\u003c\/strong\u003e Thermostat\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTemperature Rating:\u003c\/strong\u003e 143 degrees F\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOEM Cross Reference:\u003c\/strong\u003e BRP 435491\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMaterial:\u003c\/strong\u003e Plastic\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.06 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePackage Length:\u003c\/strong\u003e 3.048 centimeters\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePackage Width:\u003c\/strong\u003e 2.54 centimeters\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePackage Height:\u003c\/strong\u003e 2.54 centimeters\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 808282265533\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e200 HP outboards, 1977-83\u003c\/li\u003e\n\u003cli\u003e235 HP outboards, 1978-85\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\u003cli\u003eBRP 435491\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat temperature does the Sierra 18-3543 thermostat open at?\u003c\/strong\u003e The Sierra 18-3543 is rated to open at 143 degrees F, which is the standard operating threshold it is designed to maintain.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the 18-3543 a direct replacement for the BRP 435491 thermostat?\u003c\/strong\u003e Yes, the Sierra 18-3543 is a cross-reference equivalent for BRP part number 435491.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat outboards is the Sierra 18-3543 thermostat designed for?\u003c\/strong\u003e It fits 200 HP outboards from 1977-83 and 235 HP outboards from 1978-85.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat material is the 18-3543 thermostat made from?\u003c\/strong\u003e This thermostat is made from plastic construction suited to marine cooling system use.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the Sierra 18-3543 thermostat weigh?\u003c\/strong\u003e The 18-3543 weighs 0.06 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat are the package dimensions of the 18-3543 thermostat?\u003c\/strong\u003e The packaged unit measures 3.048 centimeters long, 2.54 centimeters wide, and 2.54 centimeters high.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the 18-3543 thermostat include installation hardware?\u003c\/strong\u003e The Sierra 18-3543 is supplied as a single thermostat unit for installation into the existing housing.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhy does my outboard need the correct thermostat temperature rating?\u003c\/strong\u003e Installing a thermostat with the wrong temperature rating, rather than the 143 degree F rating of the 18-3543, can cause the engine to run too cool or too hot, reducing efficiency and risking overheating damage.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-3543 an OEM or aftermarket part?\u003c\/strong\u003e The 18-3543 is a Sierra-branded aftermarket thermostat manufactured as a cross-reference equivalent to the OEM BRP 435491 thermostat.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat signs indicate my outboard thermostat needs replacing?\u003c\/strong\u003e Overheating alarms, erratic temperature gauge readings, or reduced cooling performance are common signs that a thermostat like the 18-3543 should be replaced.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988151087323,"sku":"SIE-18-3543","price":18.67,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-3543_lg__63631.1558126236.500.750.jpg?v=1785188941"},{"product_id":"sierra-18-3540-marine-thermostat-50c-122f-for-yamaha-outboard-9-9-250-hp-replaces-oem-6e5-12411-30-00","title":"Sierra Thermostat 18-3540, Replaces Yamaha 6E5-12411-30-00, Fits T60 and T9.9 Outboards","description":"\u003cp\u003eThe Sierra 18-3540 is a replacement thermostat for Yamaha outboard engines, designed to regulate coolant flow so the engine reaches and holds its correct operating temperature. It opens at 122 degrees F (50 degrees C), matching the calibration of the original Yamaha thermostat it replaces. Sierra manufactures this part to meet or exceed the specification of the original equipment it is designed to replace, making it a straightforward drop-in swap during routine cooling system maintenance or when troubleshooting an overheating or slow-to-warm engine.\u003c\/p\u003e\u003cp\u003eThis thermostat is finished in white and is compatible with the Yamaha T60 and T9.9 outboard models noted below. Note that the 18-3540 will not fit the 31L engine. A gasket is not included with this thermostat and should be ordered separately to match your engine.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-3540\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Type:\u003c\/strong\u003e Thermostat\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTemperature Rating:\u003c\/strong\u003e 122 degrees F \/ 50 degrees C\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eColor:\u003c\/strong\u003e White\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSpecial Feature:\u003c\/strong\u003e Adjustable\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.07 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 808282230975\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eYamaha T60 outboard (2003-06)\u003c\/li\u003e\n\u003cli\u003eYamaha T9.9 outboard (2005-06)\u003c\/li\u003e\n\u003cli\u003eWill not fit 31L engine\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\u003cli\u003e6E5-12411-30-00\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat temperature does the Sierra 18-3540 thermostat open at?\u003c\/strong\u003e The 18-3540 opens at 122 degrees F (50 degrees C), which matches the calibration of the Yamaha original equipment thermostat it replaces.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhich Yamaha outboards fit the 18-3540 thermostat?\u003c\/strong\u003e The 18-3540 fits the Yamaha T60 outboard (2003-06) and the Yamaha T9.9 outboard (2005-06). It will not fit the 31L engine.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat OEM part number does the 18-3540 replace?\u003c\/strong\u003e This thermostat replaces Yamaha OEM part number 6E5-12411-30-00.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs a gasket included with the 18-3540 thermostat?\u003c\/strong\u003e No, the Sierra 18-3540 is the thermostat only; a matching gasket is sold separately and should be selected to fit your specific engine.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat color is the Sierra 18-3540 thermostat?\u003c\/strong\u003e The 18-3540 has a white finish.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the Sierra 18-3540 thermostat weigh?\u003c\/strong\u003e The 18-3540 thermostat weighs 0.07 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-3540 a genuine Yamaha part or an aftermarket replacement?\u003c\/strong\u003e The 18-3540 is a Sierra-manufactured replacement thermostat engineered to meet or exceed the specification of the original Yamaha equipment it replaces, identified by OEM number 6E5-12411-30-00.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWill the 18-3540 fit a 31L Yamaha engine?\u003c\/strong\u003e No, the 18-3540 thermostat will not fit the 31L engine.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat symptoms indicate I need to replace this thermostat?\u003c\/strong\u003e An engine that overheats, runs cold, or warms up slowly can indicate a failed thermostat; the 18-3540 is designed to restore proper coolant regulation on covered Yamaha T60 and T9.9 outboards.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is the UPC for the Sierra 18-3540 thermostat?\u003c\/strong\u003e The UPC for the Sierra 18-3540 thermostat is 808282230975.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988151152859,"sku":"SIE-18-3540","price":21.67,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-3540_lg__24601.1558126118.500.750.jpg?v=1785188050"},{"product_id":"sierra-18-3541-thermostat-for-yamaha-outboards-f6-f100-4-stroke-replaces-66m-12411-01-00","title":"Sierra 18-3541 Thermostat, 140F\/60C, Yamaha Outboard, Replaces 66M-12411-01-00","description":"\u003cp\u003eThe Sierra 18-3541 is a replacement cooling system thermostat engineered for Yamaha outboard engines. It regulates engine operating temperature by opening at a factory-calibrated 140 degrees F (60 degrees C), allowing coolant to circulate once the engine reaches proper operating temperature and helping prevent both overheating and prolonged cold-running operation. The thermostat is finished in white and is built to Sierra's quality standard, which the company states meets or exceeds the original equipment part it replaces.\u003c\/p\u003e\u003cp\u003eThis is a direct-fit cooling system component intended for outboard owners performing routine maintenance or replacing a failed or stuck thermostat. Installing a properly rated thermostat is important for outboard longevity, since running without one or with an incorrect temperature rating can cause the engine to run too cool or too hot. The 18-3541 corresponds to the OEM Yamaha thermostat 66M-12411-01-00 used in Yamaha outboard cooling systems.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-3541\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Type:\u003c\/strong\u003e Thermostat\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTemperature Rating:\u003c\/strong\u003e 140 degrees F \/ 60 degrees C\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eColor:\u003c\/strong\u003e White\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.07 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOEM Cross Reference:\u003c\/strong\u003e 66M-12411-01-00\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eApplication:\u003c\/strong\u003e Yamaha outboard engines\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cp\u003eDesigned for Yamaha outboard engine cooling systems using the 66M-12411-01-00 thermostat.\u003c\/p\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\u003cli\u003e66M-12411-01-00\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat temperature does the Sierra 18-3541 thermostat open at?\u003c\/strong\u003e It opens at 140 degrees F (60 degrees C), which is the calibrated rating for the Sierra 18-3541 thermostat.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat OEM part number does the 18-3541 replace?\u003c\/strong\u003e The Sierra 18-3541 corresponds to Yamaha OEM thermostat 66M-12411-01-00.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-3541 an OEM or aftermarket part?\u003c\/strong\u003e It is an aftermarket replacement thermostat that Sierra states meets or exceeds the original equipment part it replaces.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat engines is the 18-3541 thermostat used on?\u003c\/strong\u003e The 18-3541 is used in Yamaha outboard engine cooling systems.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat color is the Sierra 18-3541 thermostat?\u003c\/strong\u003e It is white.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the 18-3541 thermostat weigh?\u003c\/strong\u003e The Sierra 18-3541 thermostat weighs 0.07 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the 18-3541 come with a gasket?\u003c\/strong\u003e The Sierra 18-3541 listing covers the thermostat itself; check your engine's gasket part separately when ordering.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat happens if I install a thermostat with the wrong temperature rating?\u003c\/strong\u003e Using a thermostat rated differently than 140 degrees F (60 degrees C) can cause a Yamaha outboard to run too cool or too hot, so the 18-3541 should match this rating for proper cooling system operation.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs Sierra 18-3541 covered under warranty?\u003c\/strong\u003e Yes, the Sierra 18-3541 thermostat is covered under Sierra's standard limited warranty.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow do I know if my thermostat needs replacing?\u003c\/strong\u003e Signs include an outboard engine that overheats, runs too cool, or shows inconsistent temperature gauge readings; a stuck or failed unit is commonly replaced with a direct-fit part like the Sierra 18-3541.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow many thermostats are included with the 18-3541?\u003c\/strong\u003e The Sierra 18-3541 includes one thermostat.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988151349467,"sku":"SIE-18-3541","price":31.37,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-3541_lg__72200.1558126182.500.750.jpg?v=1785188316"},{"product_id":"sierra-18-3544-marine-thermostat-for-johnson-evinrude-outboards-replaces-oem-435491-fits-e75-e175-j90-j175-1991-2006","title":"Sierra Thermostat 18-3544, Replaces OEM 435491, for Evinrude and Johnson Outboards","description":"\u003cp\u003eThe Sierra 18-3544 is a replacement thermostat engineered for Johnson and Evinrude outboard engines. It is a metal, temperature-regulating component that controls coolant flow through the engine's cooling system, helping the powerhead reach and hold proper operating temperature. As a direct replacement part, the Sierra 18-3544 is built to meet or exceed the performance of the original equipment thermostat it replaces.\u003c\/p\u003e\u003cp\u003eThis thermostat directly replaces OEM part number 435491 and is applicable across a range of Evinrude E-series and Johnson J-series outboard models and model years, as listed below. It ships as the thermostat component only.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-3544\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Type:\u003c\/strong\u003e Thermostat\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMaterial:\u003c\/strong\u003e Metal\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.2 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 808282227555\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eReplaces (OEM):\u003c\/strong\u003e 435491\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eEvinrude: E100 (2004-06), E110 (04-06), E115 (2002-06), E75 (2002-03), E90 (2002-03), E150 (1991-94), E175 (1991-94)\u003c\/li\u003e\n\u003cli\u003eJohnson: J105 (2003), J115 (2002-06), J150 (1991-92, 1993-94, 2002-06), J175 (1991-92, 1994, 2002-06), J90 (2004-06)\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\u003cli\u003e435491\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat OEM part number does the Sierra 18-3544 thermostat replace?\u003c\/strong\u003e The Sierra 18-3544 replaces OEM part number 435491.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhich outboard engines is the 18-3544 thermostat designed for?\u003c\/strong\u003e It is designed for Johnson and Evinrude outboard engines, including Evinrude E100, E110, E115, E75, E90, E150, and E175 models, and Johnson J105, J115, J150, J175, and J90 models.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the Sierra 18-3544 fit the Evinrude E175?\u003c\/strong\u003e Yes, the Sierra 18-3544 thermostat fits the Evinrude E175 for model years 1991-94.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the Sierra 18-3544 fit the Johnson J150?\u003c\/strong\u003e Yes, it fits the Johnson J150 for model years 1991-92, 1993-94, and 2002-06.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is the Sierra 18-3544 thermostat made of?\u003c\/strong\u003e The 18-3544 thermostat is constructed of metal.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the Sierra 18-3544 thermostat weigh?\u003c\/strong\u003e The Sierra 18-3544 thermostat weighs 0.2 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-3544 a genuine Sierra part or an aftermarket equivalent?\u003c\/strong\u003e The 18-3544 is a genuine Sierra-branded replacement thermostat, built to meet or exceed the performance of the original OEM 435491 thermostat it replaces.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the Sierra 18-3544 come with a gasket?\u003c\/strong\u003e No, the 18-3544 includes only the thermostat itself; no gasket is included.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-3544 the same as the Sierra 18-3546?\u003c\/strong\u003e No, the 18-3546 is a separate 130 degree F thermostat for different Evinrude and Johnson models (E200, E225, E250, J200, J225, J250) and is not interchangeable with the 18-3544.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is the UPC for the Sierra 18-3544 thermostat?\u003c\/strong\u003e The UPC for the Sierra 18-3544 thermostat is 808282227555.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWill the 18-3544 work on both Johnson and Evinrude outboards?\u003c\/strong\u003e Yes, the Sierra 18-3544 is engineered to fit specific Johnson and Evinrude outboard models as listed in its fitment, since Johnson and Evinrude share compatible thermostat designs for these engines.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the Sierra 18-3544 fit the Evinrude E115?\u003c\/strong\u003e Yes, the 18-3544 fits the Evinrude E115 for model years 2002-06.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988151513307,"sku":"SIE-18-3544","price":25.3,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-3544_lg__75173.1558126290.500.750.jpg?v=1785189190"},{"product_id":"sierra-18-3549-marine-thermostat-120f-replaces-mercury-14586-fits-mercury-100-115-125-hp-4-cylinder-outboards","title":"Sierra 18-3549 Thermostat, 120 Degree F, Replaces 803061T1, for Mercury 100\/115\/125 HP 4-Cylinder Outboards","description":"\u003cp\u003eThe Sierra 18-3549 is a 120 degree F thermostat built for Mercury outboard engines, regulating coolant flow so the engine reaches and holds proper operating temperature. It is used as the thermostat component in Mercury 100 HP, 115 HP, and 125 HP 4-cylinder outboard applications, matching the OEM 803061T1 thermostat kit specification for those engines. The thermostat is finished in white and constructed of metal for durability under continuous exposure to engine coolant and heat cycling.\u003c\/p\u003e\u003cp\u003eAs a direct temperature-control replacement part, the 18-3549 opens at the correct set point to prevent the engine from running too cool (which can cause poor combustion and increased wear) or overheating due to a stuck valve. It is a straightforward drop-in replacement for a worn, corroded, or failed thermostat and is manufactured to meet or exceed the original equipment part it replaces. This is the thermostat only; it does not include a housing gasket.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-3549\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTemperature Rating:\u003c\/strong\u003e 120 degrees F\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eColor:\u003c\/strong\u003e White\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMaterial:\u003c\/strong\u003e Metal\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.07 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFitment:\u003c\/strong\u003e Mercury 100 HP, 115 HP, and 125 HP 4-cylinder outboards\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOEM Cross Reference:\u003c\/strong\u003e 803061T1\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 808282243968\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eMercury 100 HP, 4 cylinder, serial number B209468 and up\u003c\/li\u003e\n\u003cli\u003eMercury 115 HP, 4 cylinder, serial number C100000 and up\u003c\/li\u003e\n\u003cli\u003eMercury 125 HP, 4 cylinder, serial number D283222 and up\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\u003cli\u003e803061T1\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat engines does the Sierra 18-3549 thermostat fit?\u003c\/strong\u003e It fits Mercury 100 HP (4 cylinder, serial number B209468 and up), 115 HP (4 cylinder, serial number C100000 and up), and 125 HP (4 cylinder, serial number D283222 and up) outboards.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat temperature does this thermostat open at?\u003c\/strong\u003e The Sierra 18-3549 is rated at 120 degrees F, which is the set point at which it opens to allow coolant flow through the engine.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat OEM part number does the 18-3549 replace?\u003c\/strong\u003e It replaces OEM number 803061T1, the thermostat specification used in the applicable Mercury outboard applications.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-3549 a genuine OEM part or aftermarket?\u003c\/strong\u003e It is a Sierra-manufactured aftermarket replacement thermostat that is built to meet or exceed the original equipment part it replaces.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat material is the 18-3549 thermostat made of?\u003c\/strong\u003e It is constructed of metal, sized to hold up under repeated heat cycling in the engine's cooling system.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the 18-3549 thermostat weigh?\u003c\/strong\u003e The Sierra 18-3549 thermostat weighs 0.07 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the 18-3549 come with a gasket?\u003c\/strong\u003e No, the 18-3549 is the thermostat only and does not include a housing gasket.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat color is the Sierra 18-3549 thermostat?\u003c\/strong\u003e It is finished in white.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhy would I need to replace a thermostat like the 18-3549?\u003c\/strong\u003e A stuck or worn thermostat can cause an outboard engine to run too cool or to overheat; installing a Sierra 18-3549 restores proper coolant regulation at the correct 120 degree F opening point.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs installation of the 18-3549 thermostat straightforward?\u003c\/strong\u003e Yes, the 18-3549 is designed as a direct replacement thermostat for the specified Mercury 100\/115\/125 HP 4-cylinder outboard applications.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988151742683,"sku":"SIE-18-3549","price":23.05,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-3549_lg__08528.1558126478.500.750.jpg?v=1785188041"},{"product_id":"marine-thermostat-143f-for-mercury-mariner-outboard-v135-v150-replaces-oem-75692-sierra-18-3553","title":"Sierra 18-3553 Brass Thermostat, 143 Degree F, Replaces Mercury 75692, Fits Mercury V135\/V150","description":"\u003cp\u003eThe Sierra 18-3553 is a brass thermostat built for Mercury marine engine applications. It is manufactured to control engine operating temperature at a 143 degree F rating, matching the original equipment part it replaces. The brass construction is chosen for corrosion resistance and reliable, consistent operation in a marine cooling system where saltwater and freshwater exposure can degrade lesser materials over time.\u003c\/p\u003e\u003cp\u003eThis thermostat directly replaces Mercury Marine part number 75692 and is engineered to meet or exceed the performance of the original equipment component it is designed to replace. It fits Mercury V135 and V150 series engines, including the V150 XR4, V150 XR6, and V150 MAGII variants, within the serial number ranges listed below. Confirming your engine's serial number against these ranges before ordering will help ensure correct fitment.\u003c\/p\u003e\u003cp\u003eSierra is a long-established supplier of marine replacement parts, and this thermostat is covered under Sierra's standard customer satisfaction warranty. It is a straightforward drop-in replacement for engine cooling system maintenance and repair.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-3553\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Type:\u003c\/strong\u003e Thermostat\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMaterial:\u003c\/strong\u003e Brass\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTemperature Rating:\u003c\/strong\u003e 143 degrees F\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.06 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOEM Cross Reference:\u003c\/strong\u003e 75692\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 030999236913\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFitment:\u003c\/strong\u003e Mercury V135, V150, V150 XR4, V150 XR6, V150 MAGII\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eMercury V135, serial number A904646 and up\u003c\/li\u003e\n\u003cli\u003eMercury V150, serial number A904646 and up\u003c\/li\u003e\n\u003cli\u003eMercury V150 XR4, serial number C239553 to C159199\u003c\/li\u003e\n\u003cli\u003eMercury V150 XR6, serial number D082000 and up\u003c\/li\u003e\n\u003cli\u003eMercury V150 MAGII, serial numbers C239553, 4571651\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\u003cli\u003e75692\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat engines does the Sierra 18-3553 thermostat fit?\u003c\/strong\u003e The Sierra 18-3553 thermostat fits Mercury V135 and V150 series engines, including the V150 XR4, V150 XR6, and V150 MAGII, within specific engine serial number ranges, so it is best to confirm your engine's serial number before ordering.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat temperature rating is the 18-3553 thermostat?\u003c\/strong\u003e It is rated at 143 degrees F, which is the temperature at which the thermostat opens to allow coolant flow through the engine.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat OEM part number does the Sierra 18-3553 replace?\u003c\/strong\u003e This thermostat replaces Mercury Marine OEM part number 75692.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat material is the Sierra 18-3553 thermostat made from?\u003c\/strong\u003e Brass is the material used for the Sierra 18-3553 thermostat, chosen for its corrosion resistance in marine cooling systems.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the Sierra 18-3553 thermostat weigh?\u003c\/strong\u003e The Sierra 18-3553 thermostat weighs 0.06 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-3553 a genuine Mercury Marine part or an aftermarket replacement?\u003c\/strong\u003e It is a Sierra-brand aftermarket thermostat manufactured to meet or exceed the performance of the original Mercury Marine 75692 part it replaces, not a Mercury Marine branded part.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the Sierra 18-3553 thermostat include a gasket?\u003c\/strong\u003e No, the Sierra 18-3553 is the thermostat itself; the thermostat gasket is a separate Sierra part number and should be ordered individually if needed.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat serial number range applies to the V150 XR4 engine for this thermostat?\u003c\/strong\u003e For the Mercury V150 XR4, the Sierra 18-3553 thermostat applies to engine serial numbers from C239553 to C159199.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is the UPC for the Sierra 18-3553 thermostat?\u003c\/strong\u003e The UPC for the Sierra 18-3553 thermostat is 030999236913.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-3553 thermostat covered by a warranty?\u003c\/strong\u003e Yes, the Sierra 18-3553 thermostat is covered under Sierra's standard customer satisfaction warranty.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988152922331,"sku":"SIE-18-3553","price":20.32,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-3553_lg__14106.1558126718.500.750.jpg?v=1785188764"},{"product_id":"marine-thermostat-130-degree-for-evinrude-johnson-200-225-250-hp-outboards-replaces-omc-5001036-sierra-18-3545","title":"Sierra Thermostat 130 Degree, Replaces 5001036, Fits Evinrude E200 E225 E250 \u0026 Johnson J200 J225 J250 Outboards","description":"\u003cp\u003eThis Sierra thermostat is a direct-fit replacement for select Evinrude and Johnson outboard engines, designed to maintain correct engine operating temperature by opening at 130 degrees Fahrenheit. Proper thermostat function is critical on a marine outboard: it regulates coolant flow through the powerhead so the engine reaches and holds its intended operating temperature, protecting against overheating on one end and inefficient, incomplete combustion from running too cool on the other. A worn, stuck, or corroded thermostat is a common cause of erratic temperature gauge readings, overheating alarms, or reduced performance, and replacing it is standard maintenance for these outboard models.\u003c\/p\u003e\u003cp\u003eThis thermostat is sold under Sierra part number 18-3545 and is built to replace the original equipment thermostat rated for the same 130 degree opening temperature, so it drops in without requiring a change in cooling system calibration. It is designed to fit Evinrude E200, E225, and E250 outboards (2000-05) and Johnson J200, J225, and J250 outboards (2000-01).\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-3545\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Type:\u003c\/strong\u003e Thermostat\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOpening Temperature:\u003c\/strong\u003e 130 degrees Fahrenheit\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eColor:\u003c\/strong\u003e White\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePackage Dimensions:\u003c\/strong\u003e 3.2 cm (L) x 9.6 cm (W) x 11.8 cm (H)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.04 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOEM Cross Reference:\u003c\/strong\u003e 5001036\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFitment:\u003c\/strong\u003e Evinrude E200, E225, E250 (2000-05); Johnson J200, J225, J250 (2000-01)\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eEvinrude E200, E225, E250 (2000-05)\u003c\/li\u003e\n\u003cli\u003eJohnson J200, J225, J250 (2000-01)\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\u003cli\u003e5001036\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat engines does the Sierra 18-3545 thermostat fit?\u003c\/strong\u003e The 18-3545 thermostat fits Evinrude E200, E225, and E250 outboards (2000-05), as well as Johnson J200, J225, and J250 outboards (2000-01).\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat temperature does this thermostat open at?\u003c\/strong\u003e It is rated to open at 130 degrees Fahrenheit, matching the original thermostat specification for these Evinrude and Johnson outboard models.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-3545 an OEM-equivalent part?\u003c\/strong\u003e Yes, Sierra part number 18-3545 replaces OEM number 5001036 and is built to the same 130 degree opening specification for a direct fit.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat color is the 18-3545 thermostat?\u003c\/strong\u003e This thermostat is white.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the 18-3545 thermostat weigh?\u003c\/strong\u003e It weighs 0.04 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat are the package dimensions of this thermostat?\u003c\/strong\u003e The 18-3545 thermostat ships in packaging measuring 3.2 cm (L) x 9.6 cm (W) x 11.8 cm (H).\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWill this thermostat work on a Johnson outboard as well as an Evinrude?\u003c\/strong\u003e Yes, part number 18-3545 is designed to fit both Johnson (J200, J225, J250, 2000-01) and Evinrude (E200, E225, E250, 2000-05) outboards.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat OEM part number does 18-3545 cross-reference to?\u003c\/strong\u003e It replaces OEM part number 5001036.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow do I know if my thermostat needs to be replaced?\u003c\/strong\u003e Symptoms like an overheating alarm, an erratic temperature gauge, or an engine that runs too cool typically point to a failed thermostat; the 18-3545 is the correct 130 degree replacement for the listed Evinrude and Johnson models.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs a gasket included with the 18-3545 thermostat?\u003c\/strong\u003e The listing covers the thermostat itself, part number 18-3545, rated to open at 130 degrees Fahrenheit.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan I use a different temperature rated thermostat on my Evinrude or Johnson outboard?\u003c\/strong\u003e The 18-3545 is specifically rated at 130 degrees Fahrenheit to match the original equipment specification for the E200\/E225\/E250 and J200\/J225\/J250 models; using a different rating is not covered by this part.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988152955099,"sku":"SIE-18-3545","price":20.16,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-3545_lg__70962.1558126349.500.750.jpg?v=1785188050"},{"product_id":"sierra-18-3550-marine-thermostat-140f-for-mercruiser-2-5l-3-0l-120-140-165-stern-drive-replaces-mercury-59078-f85068","title":"Sierra 18-3550 140 Degree Thermostat, Replaces 2324347, MerCruiser 120\/140\/2.5L L4","description":"\u003cp\u003eThe Sierra 18-3550 is a 140 degree F thermostat built for MerCruiser stern drive engines, regulating coolant flow so the engine reaches and holds proper operating temperature. Consistent temperature control protects against overheating and against the fuel-fouling and premature wear that comes from an engine running too cold, making the thermostat one of the most important small parts in the cooling system. The 18-3550 features a white housing and is sized to fit directly into the thermostat housing of the applicable MerCruiser L4 engines.\u003c\/p\u003e\u003cp\u003eThis thermostat is designed for MerCruiser 120 and 140 model stern drives built around the 153 cid and 181 cid L4 engine blocks, as well as the 2.5L 153 cid L4 engine. It is a direct equivalent for a range of original Mercury\/MerCruiser thermostats used across these engine families over their production runs, letting owners replace a worn or stuck thermostat without having to track down the original factory part number.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-3550\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTemperature Rating:\u003c\/strong\u003e 140 degrees F\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eColor:\u003c\/strong\u003e White\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFitment:\u003c\/strong\u003e MerCruiser 120, 140, and 2.5L stern drives with 153 cid or 181 cid L4 engines\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.08 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 030999315991\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOEM Cross Reference:\u003c\/strong\u003e 2324347, 3377340, B531853, B531854, C853255, 2508261, B450800\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eMerCruiser 120, 153 cid L4, 1968-1972\u003c\/li\u003e\n\u003cli\u003eMerCruiser 120, 153 cid L4, 1972-1986\u003c\/li\u003e\n\u003cli\u003eMerCruiser 2.5L, 153 cid L4, 1987-1989\u003c\/li\u003e\n\u003cli\u003eMerCruiser 140, 181 cid L4, 1968-1986\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e2324347\u003c\/li\u003e\n\u003cli\u003e3377340\u003c\/li\u003e\n\u003cli\u003eB531853\u003c\/li\u003e\n\u003cli\u003eB531854\u003c\/li\u003e\n\u003cli\u003eC853255\u003c\/li\u003e\n\u003cli\u003e2508261\u003c\/li\u003e\n\u003cli\u003eB450800\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat temperature rating is the Sierra 18-3550 thermostat?\u003c\/strong\u003e The Sierra 18-3550 is rated at 140 degrees F, which is the standard operating temperature setting for the MerCruiser engines it is designed for.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhich MerCruiser engines does the 18-3550 thermostat fit?\u003c\/strong\u003e It fits MerCruiser 120 and 140 model stern drives with 153 cid or 181 cid L4 engines, as well as the 2.5L 153 cid L4 engine, covering model years 1968 through 1989 across those variants.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the 18-3550 replace factory Mercury\/MerCruiser thermostats?\u003c\/strong\u003e Yes, the Sierra 18-3550 is a direct equivalent for the original equipment thermostats used on these engines, cross-referencing to OEM numbers 2324347, 3377340, B531853, B531854, C853255, 2508261, and B450800.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat color is the 18-3550 thermostat housing?\u003c\/strong\u003e The Sierra 18-3550 thermostat has a white housing.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the Sierra 18-3550 thermostat weigh?\u003c\/strong\u003e It weighs 0.08 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the 18-3550 the right part for a 140 six-cylinder MerCruiser engine?\u003c\/strong\u003e No. The 140 six-cylinder engine uses a different Sierra part number, 18-3551, so buyers with that engine should order 18-3551 rather than the 18-3550.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs there a thermostat housing kit that pairs with the 18-3550?\u003c\/strong\u003e Sierra offers a related complete thermostat housing kit under part number 18-3650 for engines where the original housing is no longer available; the 18-3550 is the thermostat itself, sold separately from that housing kit.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is included when ordering the Sierra 18-3550?\u003c\/strong\u003e The 18-3550 order includes the Sierra 140 degree thermostat unit for MerCruiser 120\/140\/2.5L L4 engines, identified by UPC 030999315991.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow do I know if I need the 18-3550 versus a different Sierra thermostat number?\u003c\/strong\u003e The 18-3550 is specific to the MerCruiser 120, 140, and 2.5L L4 engines listed in its fitment; other engine models, including the 140 six-cylinder, use different Sierra part numbers such as 18-3551, so matching your engine model and OEM cross-reference number is important before ordering.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-3550 a genuine or aftermarket thermostat?\u003c\/strong\u003e The 18-3550 is a Sierra-branded replacement thermostat manufactured to match the specifications of the original MerCruiser factory thermostats it cross-references, rather than a factory Mercury part.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988152987867,"sku":"SIE-18-3550","price":28.17,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-3550_lg__68975.1558126536.500.750.jpg?v=1785188884"},{"product_id":"sierra-18-3551-marine-engine-thermostat-160-degrees-f-replaces-oem-2463441-fits-318-360-cid-engines","title":"Sierra 18-3551 Marine Thermostat for 140 HP 6-Cylinder Engines, Replaces 1538930 1725960","description":"\u003cp\u003eThe Sierra 18-3551 is a marine engine thermostat built as a direct replacement for 140 HP 6-cylinder marine engines. It regulates coolant flow through the engine block, opening at 142 degrees F to keep raw water cooled engines running at the correct operating temperature and preventing the overheating or over-cooling that can damage cylinder heads, gaskets, and exhaust components over time. The thermostat is constructed of a metal and plastic composite housing designed to hold up under continuous marine duty in a raw water cooling system.\u003c\/p\u003e\u003cp\u003eThis part directly replaces OEM numbers 1538930 and 1725960, making it a straightforward swap for boat owners maintaining or rebuilding a 140 HP 6-cylinder marine powerplant. At just 0.12 pounds, it is a compact, easy-to-handle component that fits into the factory thermostat housing without modification. Sierra manufactures the 18-3551 to match the fit, form, and function of the original equipment thermostat it replaces, so cooling system performance and engine temperature regulation remain consistent with the factory setup.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-3551\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Type:\u003c\/strong\u003e Marine Thermostat\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.12 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTemperature Rating:\u003c\/strong\u003e 142 degrees F\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMaterial:\u003c\/strong\u003e Metal\/Plastic Composite\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 030999316004\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eEngine Fitment:\u003c\/strong\u003e 140 HP 6-Cylinder engines\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOEM Cross Reference:\u003c\/strong\u003e 1538930, 1725960\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\u003cli\u003e140 HP 6-Cylinder marine engines\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e1538930\u003c\/li\u003e\n\u003cli\u003e1725960\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat engines does the Sierra 18-3551 thermostat fit?\u003c\/strong\u003e The Sierra 18-3551 is designed for 140 HP 6-cylinder marine engines.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat temperature does the 18-3551 thermostat open at?\u003c\/strong\u003e It is rated to open at 142 degrees F, which is the standard operating temperature for the raw water cooled marine engines it services.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat OEM part numbers does the Sierra 18-3551 replace?\u003c\/strong\u003e This thermostat replaces OEM numbers 1538930 and 1725960.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the Sierra 18-3551 thermostat weigh?\u003c\/strong\u003e The Sierra 18-3551 weighs 0.12 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat material is the 18-3551 thermostat made of?\u003c\/strong\u003e Sierra 18-3551 uses a metal and plastic composite construction for the housing and internal components.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-3551 a genuine Sierra part or generic aftermarket?\u003c\/strong\u003e The 18-3551 is manufactured by Sierra as a direct aftermarket replacement engineered to match the fit and function of the original 1538930 and 1725960 thermostats.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is included when ordering the Sierra 18-3551?\u003c\/strong\u003e Ordering the Sierra 18-3551 includes one thermostat unit.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWill the 18-3551 work in a closed cooling system?\u003c\/strong\u003e The Sierra 18-3551 is intended for engines using raw water cooling; confirm your engine's cooling configuration before installing.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the Sierra 18-3551 include a gasket or housing?\u003c\/strong\u003e The Sierra 18-3551 is the thermostat itself; the thermostat housing and gasket are separate components.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow do I know if I need the 18-3551 versus a different Sierra thermostat?\u003c\/strong\u003e Confirm your engine is a 140 HP 6-cylinder model and cross-check your original thermostat against OEM numbers 1538930 or 1725960 before ordering the 18-3551.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988153053403,"sku":"SIE-18-3551","price":16.71,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-3551_lg__51506.1558126605.500.750.jpg?v=1785188116"},{"product_id":"sierra-18-3555-marine-thermostat-160f-replaces-mercruiser-99155a1-fits-1998-newer-gm-v-6-v-8-with-closed-cooling","title":"Sierra 18-3555 Thermostat, 160 Degree, for Mercruiser 7.4L MIE 454 V-8 Closed Cooling 1996-1997","description":"\u003cp\u003eThe Sierra 18-3555 is a 160 degree marine thermostat engineered for Mercruiser 7.4L MIE 454 cubic inch V-8 stern drive engines equipped with closed (fresh water) cooling. It mounts at the engine block and regulates coolant flow through the closed cooling loop, opening at 160 degrees Fahrenheit to keep the engine operating in its correct temperature range for efficient combustion and reduced wear. The thermostat is finished in white and installs using the standard engine block mount configuration found on this Mercruiser engine family. It is built to meet or exceed the performance of the original equipment component it replaces, making it a straightforward like-for-like replacement for a worn, stuck, or failed thermostat. This part is specific to the 7.4L EFI MIE 454 V-8 configuration with closed cooling covering the 1996-1997 model years and the serial number range noted in the fitment section below, so confirm your engine's cooling system type and serial number before ordering. Keeping the thermostat within spec protects against overheating and helps the engine reach efficient operating temperature faster after startup.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-3555\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTemperature Rating:\u003c\/strong\u003e 160 degrees Fahrenheit\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCooling System Type:\u003c\/strong\u003e Closed Cooling (Fresh Water Cooling)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eColor:\u003c\/strong\u003e White\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMounting Type:\u003c\/strong\u003e Engine Block Mount\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.07 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 030999316035\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\u003cli\u003eMercruiser MIE 7.4L EFI 454 cubic inch V-8, Closed Cooling, 1996-1997, serial numbers F874815 through K999999\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eGLM 13040\u003c\/li\u003e\n\u003cli\u003eMallory 9-43001\u003c\/li\u003e\n\u003cli\u003eMallory 9-43016\u003c\/li\u003e\n\u003cli\u003eMercruiser Stern Drive 991551\u003c\/li\u003e\n\u003cli\u003eMercruiser Stern Drive 99155A1\u003c\/li\u003e\n\u003cli\u003eMercruiser Stern Drive 99155T2\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat temperature does the Sierra 18-3555 thermostat open at?\u003c\/strong\u003e The Sierra 18-3555 is rated to open at 160 degrees Fahrenheit, which is the standard operating temperature for the Mercruiser closed cooling systems it is designed for.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhich engines does the 18-3555 thermostat fit?\u003c\/strong\u003e This thermostat fits Mercruiser MIE 7.4L EFI 454 cubic inch V-8 engines with closed cooling, covering the 1996-1997 model years within serial number range F874815 through K999999.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the 18-3555 work on standard raw water cooled engines?\u003c\/strong\u003e No. The 18-3555 is built for the closed (fresh water) cooling version of the Mercruiser 7.4L EFI MIE 454 V-8; engines with standard raw water cooling use a different Sierra thermostat.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat OEM part numbers does the Sierra 18-3555 cross-reference?\u003c\/strong\u003e The 18-3555 interchanges with GLM 13040, Mallory 9-43001 and 9-43016, and Mercruiser Stern Drive 991551, 99155A1, and 99155T2.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-3555 a genuine Mercruiser part or aftermarket?\u003c\/strong\u003e The 18-3555 is a Sierra aftermarket thermostat manufactured to meet or exceed the performance of the original Mercruiser equipment it replaces, not a Mercruiser-branded part.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the 18-3555 thermostat weigh?\u003c\/strong\u003e The Sierra 18-3555 thermostat weighs 0.07 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat color is the 18-3555 thermostat?\u003c\/strong\u003e The 18-3555 has a white finish.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow does the 18-3555 mount to the engine?\u003c\/strong\u003e It uses an engine block mount configuration, installing directly at the engine block on the closed cooling loop of the Mercruiser 7.4L MIE 454 V-8.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is included when I order the 18-3555?\u003c\/strong\u003e The listing includes one Sierra 18-3555 160 degree marine thermostat.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhy would I replace my thermostat with the 18-3555?\u003c\/strong\u003e A stuck, corroded, or out-of-spec thermostat can cause a Mercruiser 7.4L MIE 454 V-8 to run too hot or too cold; the 18-3555 restores the correct 160 degree opening point for the closed cooling system.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs there a UPC for the Sierra 18-3555?\u003c\/strong\u003e Yes, the Sierra 18-3555 thermostat carries UPC 030999316035.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988153184475,"sku":"SIE-18-3555","price":20.39,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-3555_lg__34723.1558126853.500.750.jpg?v=1785188005"},{"product_id":"sierra-18-3554-marine-thermostat-replaces-omc-383307-fits-omc-stern-drive-inboard-143f","title":"Sierra Thermostat 18-3554, 143 Degree F, OMC Stern Drive Replacement, OE 383307","description":"\u003cp\u003eThe Sierra 18-3554 Thermostat is a replacement engine thermostat designed for use in OMC stern drive applications. It regulates coolant flow to keep the engine operating within its designed temperature range, opening at a rated temperature of 143 degrees F to protect against overheating while allowing the engine to reach efficient operating temperature quickly. The thermostat is built from alloy steel with a glossy white finish and is sized to fit directly in place of the original equipment thermostat it replaces.\u003c\/p\u003e\u003cp\u003eSierra manufactures this thermostat to meet or exceed the specifications of the original equipment part it replaces, making it a straightforward drop-in replacement for boat owners performing routine cooling system maintenance or troubleshooting an overheating engine. It is part of a broader Sierra thermostat kit lineup that also includes matching manifold and thermostat gaskets, sold separately under their own part numbers.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-3554\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Dimensions:\u003c\/strong\u003e 2.6 inches D x 2.6 inches W x 0.6 inches H\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.1 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTemperature Rating:\u003c\/strong\u003e 143 degrees F\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eColor:\u003c\/strong\u003e White\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMaterial:\u003c\/strong\u003e Alloy Steel\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFinish:\u003c\/strong\u003e Glossy\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCountry of Origin:\u003c\/strong\u003e China\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 030999316028\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCategory:\u003c\/strong\u003e OMC Thermostats \u0026amp; Gaskets\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cp\u003eDesigned for use in OMC stern drive applications.\u003c\/p\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\u003cli\u003e383307\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat temperature does the Sierra 18-3554 thermostat open at?\u003c\/strong\u003e The Sierra 18-3554 thermostat is rated to open at 143 degrees F, regulating coolant flow to keep the engine within its designed operating temperature range.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat applications is the 18-3554 thermostat designed for?\u003c\/strong\u003e This Sierra thermostat is designed for use in OMC stern drive applications.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-3554 an OEM equivalent part?\u003c\/strong\u003e Yes, the 18-3554 replaces original equipment part number 383307, and Sierra builds each thermostat to meet or exceed the specifications of the original equipment part it replaces.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat color is the 18-3554 thermostat?\u003c\/strong\u003e The 18-3554 thermostat has a white glossy finish.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat material is the Sierra 18-3554 thermostat made from?\u003c\/strong\u003e It is made from alloy steel with a glossy finish.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the 18-3554 thermostat weigh?\u003c\/strong\u003e The Sierra 18-3554 thermostat weighs 0.1 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat are the dimensions of the 18-3554 thermostat?\u003c\/strong\u003e The Sierra 18-3554 measures 2.6 inches D x 2.6 inches W x 0.6 inches H.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the 18-3554 come with the gaskets needed for installation?\u003c\/strong\u003e The 18-3554 is the thermostat itself; matching manifold and thermostat gaskets for this kit are sold as separate Sierra part numbers, so buyers replacing the full thermostat kit should order the gaskets alongside 18-3554.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhere is the Sierra 18-3554 thermostat manufactured?\u003c\/strong\u003e The country of origin for the 18-3554 thermostat is China.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is the UPC for the Sierra 18-3554 thermostat?\u003c\/strong\u003e The UPC for the Sierra 18-3554 thermostat is 030999316028.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988153217243,"sku":"SIE-18-3554","price":28.35,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-3554_lg__12655.1558126785.500.750.jpg?v=1785188639"},{"product_id":"sierra-18-3556-marine-thermostat-130f-replaces-f97068-2-fits-force-outboard-85-hp-125-hp","title":"Sierra 18-3556 Thermostat 130 Degree F for Chrysler\/Force Outboards, Replaces F97068","description":"\u003cp\u003eThe Sierra 18-3556 is a 130 degree F thermostat built for Chrysler\/Force outboard cooling systems. It regulates coolant flow through the powerhead so the engine reaches and holds its correct operating temperature, which protects against overheating on one end and inefficient, overly cold running on the other. The thermostat measures 3\/4 inch (19.1mm) and is constructed of metal for durability in a marine cooling environment.\u003c\/p\u003e\u003cp\u003eSierra manufactures this thermostat to meet or exceed the performance of the original equipment part it replaces, making it a straightforward drop-in replacement when a Chrysler\/Force outboard thermostat has failed or is sticking open or closed. It fits a range of Chrysler\/Force outboard horsepower ratings across multiple model years, and is also functionally interchangeable with several Chrysler\/Force\/US Marine, GLM, Mallory, and Mercury Marine part numbers, so it can be used as a cross-reference replacement regardless of which of those brands originally shipped on the engine.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-3556\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTemperature Rating:\u003c\/strong\u003e 130 degrees F\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSize:\u003c\/strong\u003e 3\/4 inch (19.1mm)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMaterial:\u003c\/strong\u003e Metal\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.03 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 030999563002\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOEM Cross Reference:\u003c\/strong\u003e F97068, F97068-1, F97068-2, GLM 13200, Mallory 9-43025, Mercury Marine 895338\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eChrysler\/Force 25 HP, 1996-1998, Serial No. E127700-E344999\u003c\/li\u003e\n\u003cli\u003eChrysler\/Force 35 HP, 1976-1978\u003c\/li\u003e\n\u003cli\u003eChrysler\/Force 35 HP, 1983-1984\u003c\/li\u003e\n\u003cli\u003eChrysler\/Force 35 HP, 1986-1988\u003c\/li\u003e\n\u003cli\u003eChrysler\/Force 50 HP, 1984-91, 1992A\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eF97068\u003c\/li\u003e\n\u003cli\u003eF97068-1\u003c\/li\u003e\n\u003cli\u003eF97068-2\u003c\/li\u003e\n\u003cli\u003eGLM 13200\u003c\/li\u003e\n\u003cli\u003eMallory 9-43025\u003c\/li\u003e\n\u003cli\u003eMercury Marine 895338\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat temperature is the Sierra 18-3556 thermostat rated for?\u003c\/strong\u003e The Sierra 18-3556 opens at 130 degrees F, which is the standard operating temperature setting for the Chrysler\/Force outboard applications it fits.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat size is this thermostat?\u003c\/strong\u003e The 18-3556 measures 3\/4 inch, also expressed as 19.1mm, which is the standard thermostat housing size for its listed Chrysler\/Force outboard fitments.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhich Chrysler\/Force outboards use the 18-3556 thermostat?\u003c\/strong\u003e It fits Chrysler\/Force 25 HP outboards from 1996-1998 (serial range E127700-E344999), 35 HP outboards from 1976-1978, 1983-1984, and 1986-1988, and 50 HP outboards from 1984-91 and 1992A.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the 18-3556 a genuine OEM part or an aftermarket replacement?\u003c\/strong\u003e Sierra 18-3556 is manufactured by Sierra as a marine replacement part engineered to meet or exceed the performance of the original equipment thermostat it replaces.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat OEM part numbers does the 18-3556 cross-reference to?\u003c\/strong\u003e It is interchangeable with Chrysler\/Force\/US Marine F97068, F97068-1, and F97068-2, GLM 13200, Mallory 9-43025, and Mercury Marine 895338.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat material is the thermostat made from?\u003c\/strong\u003e The Sierra 18-3556 is constructed of metal, built to hold up to the heat cycling and marine environment of an outboard cooling system.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the 18-3556 thermostat weigh?\u003c\/strong\u003e It weighs 0.03 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWill this thermostat work if my engine has an F97068 or Mercury Marine 895338 thermostat installed?\u003c\/strong\u003e Yes, the Sierra 18-3556 is functionally interchangeable with F97068, F97068-1, F97068-2, and Mercury Marine 895338, along with GLM 13200 and Mallory 9-43025.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the 18-3556 come with a gasket?\u003c\/strong\u003e The dossier for this listing covers the 18-3556 thermostat itself; no gasket or seal is specified as included.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat happens if I install a thermostat with the wrong temperature rating?\u003c\/strong\u003e Using a thermostat other than the specified 130 degree F rating for a Chrysler\/Force outboard can cause the engine to run at an incorrect operating temperature, so the 18-3556's 130 degree F rating should be matched to the original spec for correct engine cooling.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the 18-3556 the correct thermostat for a 25 HP Chrysler\/Force outboard?\u003c\/strong\u003e For a 25 HP Chrysler\/Force outboard built in 1996-1998 within serial range E127700-E344999, the 18-3556 is the listed thermostat.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow do I know if the UPC matches this thermostat?\u003c\/strong\u003e The Sierra 18-3556 thermostat carries UPC 030999563002, which can be used to confirm it against the part in hand.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988153675995,"sku":"SIE-18-3556","price":32.1,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-3556_lg__35699.1558126931.500.750.jpg?v=1785188857"},{"product_id":"sierra-18-3557-marine-thermostat-130f-replaces-evinrude-johnson-f335068-for-omc-outboard-cooling-systems","title":"Sierra 18-3557 143 Degree Marine Thermostat, White, Replaces Volvo Penta 21148403","description":"\u003cp\u003eThe Sierra 18-3557 is a 143 degree marine thermostat engineered to regulate engine coolant flow and keep your marine engine operating at the correct temperature range for efficient combustion and reduced wear. It is a white, plastic-bodied thermostat sized for direct fitment as a replacement engine cooling component, correcting overheating or slow-warm-up issues caused by a stuck, corroded, or failed factory thermostat. Installing a fresh thermostat is one of the most common and effective ways to restore proper engine temperature control and protect against overheating damage to gaskets, hoses, and engine internals.\u003c\/p\u003e\u003cp\u003eThe 18-3557 cross-references directly to Volvo Penta OE part number 21148403, giving boat owners and marine technicians a straightforward aftermarket alternative to the OEM part. It is sold as a standalone thermostat and is compatible with cooling systems designed around the referenced Volvo Penta OE number.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-3557\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTemperature Rating:\u003c\/strong\u003e 143 Degrees F\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eColor:\u003c\/strong\u003e White\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMaterial:\u003c\/strong\u003e Plastic\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.05 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 030999563019\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOEM Cross Reference:\u003c\/strong\u003e 21148403\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\u003cli\u003eVolvo Penta engines using OE part number 21148403\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\u003cli\u003e21148403\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat temperature rating is the Sierra 18-3557 thermostat?\u003c\/strong\u003e The Sierra 18-3557 is rated to open at 143 degrees Fahrenheit, which regulates when coolant begins circulating through the engine.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat OEM part does the Sierra 18-3557 replace?\u003c\/strong\u003e It replaces Volvo Penta OE part number 21148403, making it a direct cross-reference for that engine cooling application.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is the Sierra 18-3557 made of?\u003c\/strong\u003e This thermostat has a white, plastic housing designed for durability in a marine engine cooling system.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the Sierra 18-3557 thermostat weigh?\u003c\/strong\u003e The Sierra 18-3557 weighs 0.05 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-3557 a genuine Volvo Penta part or aftermarket?\u003c\/strong\u003e The 18-3557 is a Sierra-manufactured aftermarket thermostat built to replace Volvo Penta OE number 21148403, not a Volvo-branded part.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat comes in the box with the 18-3557?\u003c\/strong\u003e The Sierra 18-3557 ships as a standalone thermostat unit.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan I use the 18-3557 as a routine maintenance replacement?\u003c\/strong\u003e Yes, replacing a thermostat like the Sierra 18-3557 on a routine or preventive basis, or at the first sign of overheating or slow warm-up, helps maintain proper engine temperature control.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the Sierra 18-3557 fit any thermostat housing?\u003c\/strong\u003e The 18-3557 is designed for engines that originally used Volvo Penta OE part 21148403; confirm your existing thermostat's part number matches before ordering.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat color is the Sierra 18-3557 thermostat?\u003c\/strong\u003e It is white in color with a plastic body.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow do I know if my thermostat needs replacing?\u003c\/strong\u003e Symptoms like engine overheating, slow warm-up, or fluctuating temperature gauges often indicate a failed thermostat, and installing a Sierra 18-3557 is a common fix when your engine uses the 21148403 reference.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-3557 the same as other Sierra thermostats?\u003c\/strong\u003e No, the 18-3557 is a distinct Sierra part number specifically cross-referenced to Volvo Penta 21148403; other Sierra thermostat part numbers correspond to different OEM applications.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988153741531,"sku":"SIE-18-3557","price":28.53,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-3557_lg__42732.1558126994.500.750.jpg?v=1785188005"},{"product_id":"sierra-18-3568-thermostat-kit-160f-replaces-mercruiser-99155t1-fits-5-7-mie-mx6-2l-mpi-454-horizon-mie-502-mag-mpi-closed-cooling-engines","title":"Sierra Thermostat Kit 18-3568, 160 Degree F, MerCruiser Closed Cooling 7.4L 454 V-8, Replaces Mercruiser 99155T1","description":"\u003cp\u003eThe Sierra 18-3568 Thermostat Kit is a complete replacement thermostat and seal set built for closed-cooling MerCruiser V-8 engines. It supplies a 160 degree F thermostat along with a matching seal, giving the cooling system the correct opening temperature to keep engine operating temperature in the proper range. Marine thermostats regulate coolant flow between the engine block and the heat exchanger, and using the correct temperature rating and a fresh seal at each replacement helps prevent leaks and overheating.\u003c\/p\u003e\u003cp\u003eThis kit is designed for MerCruiser 7.4L EFI MIE FWC 454 cid V-8 engines and is also compatible with GM V-6 and V-8 engines equipped with closed cooling. It is built to meet or exceed the performance of the original equipment part it replaces, and it is interchangeable with Mercruiser part number 99155T1, making it a straightforward replacement when the factory thermostat or seal fails or when performing routine cooling system maintenance. The kit ships complete with the thermostat and seal needed to complete the job in a single purchase, without having to source separate components.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-3568\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Type:\u003c\/strong\u003e Thermostat Kit\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eThermostat Temperature Rating:\u003c\/strong\u003e 160 degrees F\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCooling System Type:\u003c\/strong\u003e Closed Cooling\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eIncluded Components:\u003c\/strong\u003e Thermostat (18-3555), Thermostat Seal (18-1508)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.17 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 808282112783\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eMerCruiser 7.4L EFI MIE FWC 454 cid V-8 (1996-1997), closed cooling\u003c\/li\u003e\n\u003cli\u003eGM V-6 \u0026amp; V-8 engines with closed cooling (1998 \u0026amp; newer)\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\u003cli\u003eMercruiser 99155T1\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat temperature does the Sierra 18-3568 thermostat open at?\u003c\/strong\u003e The Sierra 18-3568 thermostat kit opens at 160 degrees F.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is included in the Sierra 18-3568 thermostat kit?\u003c\/strong\u003e The kit contains a thermostat (part 18-3555) and a thermostat seal (part 18-1508), everything needed to complete the replacement.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat engines does the Sierra 18-3568 thermostat kit fit?\u003c\/strong\u003e It fits MerCruiser 7.4L EFI MIE FWC 454 cid V-8 engines (1996-1997) with closed cooling, as well as GM V-6 and V-8 engines with closed cooling (1998 and newer).\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the 18-3568 kit work with raw water or standard cooling systems?\u003c\/strong\u003e No, the Sierra 18-3568 is designed specifically for closed-cooling systems, not standard raw water cooling.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-3568 interchangeable with any Mercruiser part number?\u003c\/strong\u003e Yes, the 18-3568 thermostat kit is interchangeable with Mercruiser 99155T1.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the Sierra 18-3568 thermostat kit weigh?\u003c\/strong\u003e It weighs 0.17 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-3568 an OEM or aftermarket part?\u003c\/strong\u003e It is an aftermarket replacement kit that Sierra states meets or exceeds the performance of the original equipment part it replaces.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDo I need to replace the thermostat seal along with the thermostat?\u003c\/strong\u003e Yes, and the 18-3568 kit makes this easy since it already includes both the 18-3555 thermostat and the 18-1508 seal in one package.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is the UPC code for the Sierra 18-3568 thermostat kit?\u003c\/strong\u003e The UPC for the Sierra 18-3568 Thermostat Kit is 808282112783.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow is the 18-3568 different from Sierra's 18-3647 thermostat kit?\u003c\/strong\u003e The 18-3568 is built for closed-cooling MerCruiser 7.4L EFI MIE FWC engines (1996-1997), while the 18-3647 covers the same 7.4L EFI MIE engine and years but for standard cooling instead of closed cooling.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWill the 18-3568 kit fix an overheating MerCruiser engine?\u003c\/strong\u003e A stuck or incorrectly rated thermostat is a common cause of marine engine overheating, and installing the correctly rated 160 degree F Sierra 18-3568 kit with a new seal addresses that specific failure point on closed-cooling MerCruiser 454 V-8 engines.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988153774299,"sku":"SIE-18-3568","price":21.88,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-3568_lg__38122.1558124605.500.750.jpg?v=1785188379"},{"product_id":"sierra-18-3561-marine-thermostat-143f-replaces-oem-436195-for-evinrude-johnson-outboards","title":"Sierra 18-3561 Thermostat 105 Degree - Replaces 384719 - Fits Most 3 and 4 Cyl. Outboards 1985-90","description":"\u003cp\u003eThe Sierra 18-3561 is a 105 degree F thermostat built as a direct replacement for outboard engine cooling systems. It regulates coolant flow through the powerhead, opening at its rated temperature to maintain consistent operating temperature and protect the engine from overheating or running too cold. This thermostat fits most 3 and 4 cylinder outboard engines from 1985-90 and is a direct replacement for OEM part number 384719.\u003c\/p\u003e\u003cp\u003eInstalling the correct thermostat is essential for reliable engine performance. A thermostat that fails to open can cause overheating and engine damage, while one that fails to close can prevent the engine from reaching proper operating temperature, leading to poor fuel combustion and increased wear. The Sierra 18-3561 is manufactured to meet or exceed the specifications of the original equipment part it replaces, giving boat owners a dependable option when replacing a worn, stuck, or failed thermostat during routine maintenance.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-3561\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTemperature Rating:\u003c\/strong\u003e 105 degrees F\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eReplaces (OEM):\u003c\/strong\u003e 384719\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFitment:\u003c\/strong\u003e Fits most 3 and 4 cylinder outboard engines, 1985-90\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.02 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMaterial:\u003c\/strong\u003e Brass\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eColor:\u003c\/strong\u003e White\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 030999753656\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\u003cli\u003eMost 3 and 4 cylinder outboard engines, 1985-90\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\u003cli\u003e384719\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat temperature does the Sierra 18-3561 thermostat open at?\u003c\/strong\u003e The Sierra 18-3561 thermostat is rated to open at 105 degrees F, allowing coolant to begin circulating through the powerhead once that temperature is reached.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat engines does the 18-3561 thermostat fit?\u003c\/strong\u003e This thermostat fits most 3 and 4 cylinder outboard engines built from 1985-90.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the 18-3561 a direct replacement for the original equipment thermostat?\u003c\/strong\u003e Yes, the Sierra 18-3561 is a direct replacement for OEM part number 384719 and is designed to meet or exceed the performance of the original part.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is the 18-3561 thermostat made of?\u003c\/strong\u003e The Sierra 18-3561 thermostat is constructed of brass with a white finish.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the 18-3561 thermostat weigh?\u003c\/strong\u003e The Sierra 18-3561 thermostat weighs 0.02 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow do I know if my outboard thermostat needs to be replaced?\u003c\/strong\u003e Signs that an outboard thermostat like the Sierra 18-3561 needs replacement include the engine running hot, overheating alarms, or the engine taking unusually long to reach normal operating temperature.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan I install the Sierra 18-3561 myself?\u003c\/strong\u003e The Sierra 18-3561 thermostat is a standard replacement part designed to install in place of the original 384719 thermostat using the same mounting location in the powerhead cooling system.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the 18-3561 come with a gasket or seal?\u003c\/strong\u003e The listing for the Sierra 18-3561 covers the thermostat itself; check your engine's cooling system for the correct matching gasket or housing seal when replacing it.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhy does thermostat temperature rating matter on an outboard engine?\u003c\/strong\u003e A thermostat's temperature rating, such as the 105 degree F rating on the 18-3561, determines when coolant begins flowing to regulate engine temperature; using the wrong rating can cause the engine to run too hot or too cold.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-3561 a genuine OEM part or an aftermarket replacement?\u003c\/strong\u003e The Sierra 18-3561 is manufactured by Sierra as a replacement part for OEM number 384719, engineered to meet or exceed original equipment specifications.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988153807067,"sku":"SIE-18-3561","price":15.2,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-3561_lg__47578.1558127256.500.750.jpg?v=1785188216"},{"product_id":"sierra-18-3569-marine-thermostat-kit-replaces-mercury-803061t1-fits-mercury-mariner-100-115-125-hp-4-cyl-outboards","title":"Sierra 18-3569 Marine Thermostat Kit, 120 F, for Mercury\/Mariner 70-125 HP 2 Cycle Outboards 1987 and Newer","description":"\u003cp\u003eThe Sierra 18-3569 Thermostat Kit is a complete cooling-system repair kit for Mercury and Mariner 2 cycle outboard motors. It is built around a 120 F rated thermostat and includes the gaskets needed for a proper reinstall, so the job can be done in one pass without hunting down separate gasket parts. Marine thermostats regulate engine operating temperature by controlling coolant flow, and a stuck or worn unit is a common cause of overheating or slow warm-up in outboard motors -- this kit lets you replace the thermostat and both related gaskets together.\u003c\/p\u003e\u003cp\u003eThe kit includes one 18-3549 thermostat, one 18-0182 thermostat gasket, and one 18-0339 thermostat cover gasket. It is designed to fit various Mercury\/Mariner 70-125 HP 2 cycle outboards from 1987 and newer. Sierra manufactures its cooling components to meet or exceed the specifications of the original equipment they replace, making this kit a straightforward like-for-like replacement for the factory thermostat assembly.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-3569\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Name:\u003c\/strong\u003e Thermostat Kit\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eThermostat Temperature Rating:\u003c\/strong\u003e 120 F\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eIncluded Components:\u003c\/strong\u003e 1 x 18-3549 Thermostat, 1 x 18-0182 Thermostat Gasket, 1 x 18-0339 Thermostat Cover Gasket\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.08 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 808282112899\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\u003cli\u003eVarious Mercury\/Mariner 70-125 HP 2 cycle outboards, 1987 and newer\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eGLM 13124\u003c\/li\u003e\n\u003cli\u003eMallory 9-43155\u003c\/li\u003e\n\u003cli\u003eMercury Marine 803061T1\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat does the Sierra 18-3569 Thermostat Kit include?\u003c\/strong\u003e The kit includes one 18-3549 thermostat, one 18-0182 thermostat gasket, and one 18-0339 thermostat cover gasket, so both gaskets needed for the reinstall are included along with the thermostat itself.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat outboards does the 18-3569 thermostat kit fit?\u003c\/strong\u003e It fits various Mercury\/Mariner 70-125 HP 2 cycle outboards, 1987 and newer.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat temperature is the thermostat in kit 18-3569 rated for?\u003c\/strong\u003e 120 F is the temperature rating of the thermostat included in the Sierra 18-3569 kit.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-3569 kit interchangeable with OEM Mercury Marine parts?\u003c\/strong\u003e Yes, it is interchangeable with Mercury Marine 803061T1, as well as GLM 13124 and Mallory 9-43155.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs Mallory 9-43155 the same as Sierra 18-3569?\u003c\/strong\u003e Mallory 9-43155 cross-references directly to Sierra 18-3569, so the two part numbers refer to the same thermostat kit application.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the 18-3569 thermostat kit weigh?\u003c\/strong\u003e The Sierra 18-3569 Thermostat Kit weighs 0.08 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDo I need to buy separate gaskets with this thermostat?\u003c\/strong\u003e No, the 18-3569 kit already includes the 18-0182 thermostat gasket and the 18-0339 thermostat cover gasket along with the thermostat, so no separate gaskets are needed.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWill the 18-3569 kit fit a 4 stroke Mercury outboard?\u003c\/strong\u003e The Sierra 18-3569 Thermostat Kit is designed for Mercury\/Mariner 70-125 HP 2 cycle outboards, 1987 and newer, not 4 stroke models.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes Sierra make this thermostat kit to OEM standards?\u003c\/strong\u003e Sierra manufactures the 18-3569 Thermostat Kit to meet or exceed the specifications of the original equipment part it replaces.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is the UPC for the Sierra 18-3569 Thermostat Kit?\u003c\/strong\u003e The UPC for the Sierra 18-3569 Thermostat Kit is 808282112899.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988153938139,"sku":"SIE-18-3569","price":26.05,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-3569_lg__50978.1558124669.500.750.jpg?v=1785188284"},{"product_id":"yamaha-outboard-thermostat-kit-sierra-18-3608-fits-115-225-hp-v4-v6-outboards-1991-2002","title":"Sierra 18-3608 Thermostat Kit, Replaces 6J8-12414-A0-00, for Yamaha 2-Stroke Outboard Engines","description":"\u003cp\u003eThe Sierra 18-3608 Thermostat Kit is a complete cooling system repair kit for Yamaha 2-stroke outboard engines. Replacing a worn or stuck-open thermostat is one of the most common fixes for an outboard that runs cold, overheats, or shows erratic temperature swings, and this kit supplies both parts needed to do the job correctly in one purchase: a thermostat and the matching gasket. The thermostat is rated to open at 60 degrees Celsius, matching the original equipment opening temperature so the engine reaches and holds proper operating temperature for efficient combustion and long-term reliability.\u003c\/p\u003e\u003cp\u003eSierra engineers this kit to meet or exceed the original equipment part it replaces, so it installs the same way the factory thermostat and gasket did, with no modification required. Because the kit bundles the gasket with the thermostat, there is no need to source a separate gasket or risk reusing an old one that no longer seals properly. This is a direct fit for the Yamaha 2-stroke outboard cooling system application covered by part number 18-3608.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-3608\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Type:\u003c\/strong\u003e Thermostat Kit\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eApplication:\u003c\/strong\u003e Yamaha 2-Stroke Outboard Engines\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eThermostat Temperature Rating:\u003c\/strong\u003e 60 degrees Celsius\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eKit Contents:\u003c\/strong\u003e Thermostat and gasket\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOEM Cross Reference:\u003c\/strong\u003e 6J8-12414-A0-00, 66M-12411-01-00, 62Y-12414-00-00\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.08 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 808282256807\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cp\u003eYamaha 2-stroke outboard engines using the cooling system thermostat and gasket set covered by OEM number 6J8-12414-A0-00.\u003c\/p\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e6J8-12414-A0-00\u003c\/li\u003e\n\u003cli\u003e66M-12411-01-00\u003c\/li\u003e\n\u003cli\u003e62Y-12414-00-00\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat is included in the Sierra 18-3608 thermostat kit?\u003c\/strong\u003e The 18-3608 kit includes a thermostat and the matching gasket needed to complete the cooling system repair, so no separate gasket purchase is required.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat temperature does the thermostat open at?\u003c\/strong\u003e The thermostat in the 18-3608 kit is rated to open at 60 degrees Celsius, matching the original equipment opening temperature for the Yamaha 2-stroke cooling system it services.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat OEM part numbers does the 18-3608 kit replace?\u003c\/strong\u003e This kit replaces OEM numbers 6J8-12414-A0-00, 66M-12411-01-00, and 62Y-12414-00-00.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat engines is the Sierra 18-3608 designed for?\u003c\/strong\u003e It is designed for Yamaha 2-stroke outboard engines that use the cooling system thermostat and gasket covered by OEM number 6J8-12414-A0-00.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the 18-3608 thermostat kit weigh?\u003c\/strong\u003e The Sierra 18-3608 Thermostat Kit weighs 0.08 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-3608 a genuine OEM part or an aftermarket replacement?\u003c\/strong\u003e It is a Sierra aftermarket kit engineered to meet or exceed the original equipment part it replaces, so it installs and performs the same as the factory thermostat and gasket.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the kit come with the gasket, or just the thermostat?\u003c\/strong\u003e Both are included: the 18-3608 kit contains the thermostat and its matching gasket in a single package.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is the UPC for this product?\u003c\/strong\u003e The UPC for the Sierra 18-3608 Thermostat Kit is 808282256807.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow do I confirm the 18-3608 kit fits my Yamaha outboard?\u003c\/strong\u003e Check that your engine's original thermostat or gasket carries the OEM number 6J8-12414-A0-00, 66M-12411-01-00, or 62Y-12414-00-00, since the 18-3608 kit replaces all three.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the Sierra 18-3608 include a warranty?\u003c\/strong\u003e Yes, the Sierra 18-3608 Thermostat Kit is covered under Sierra's standard limited warranty.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan the 18-3608 kit be installed without modifying the engine?\u003c\/strong\u003e Yes, the 18-3608 thermostat and gasket are designed as a direct replacement, installing the same way as the original equipment parts with no modification needed.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988154855643,"sku":"SIE-18-3608","price":28.15,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-3608_lg__28822.1558126080.500.750.jpg?v=1785188299"},{"product_id":"thermostat-kit-130-degrees-f-for-mercury-mariner-200-225-250-3-0l-dfi-dts-efi-outboards-sierra-18-3606","title":"Sierra 18-3606 Thermostat Kit 130F for Mercury\/Mariner V-135 DFI, V-150 DFI, V-175 DFI Outboards","description":"\u003cp\u003eThe Sierra 18-3606 Thermostat Kit is a marine engine cooling component built for Mercury\/Mariner outboard motors, supplying a 130F thermostat in a white housing to regulate engine operating temperature. Maintaining the correct thermostat rating keeps the engine within its intended temperature range, which protects against overheating and supports consistent cooling system performance in the harsh marine environment. This kit is designed to install into the cooling passage of the outboard powerhead in place of a worn, stuck, or failed thermostat, restoring proper temperature regulation and helping the engine reach and hold its designed operating range.\u003c\/p\u003e\u003cp\u003eSierra manufactures marine parts engineered to meet the demands of high-horsepower engines while standing up to saltwater and freshwater marine conditions, and supplies OEM engine manufacturers and boat builders with parts on a daily basis. The 18-3606 kit fits specific Mercury\/Mariner DFI outboard models, so confirming the exact engine designation before ordering ensures the correct thermostat rating and fit for the cooling system.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-3606\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Type:\u003c\/strong\u003e Thermostat Kit\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTemperature Rating:\u003c\/strong\u003e 130 degrees F\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eColor:\u003c\/strong\u003e White\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.1 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 808282256784\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eMercury\/Mariner V-135 DFI (2.5L), 1998 and up\u003c\/li\u003e\n\u003cli\u003eMercury\/Mariner V-150 DFI (2.5L), 1998 and up\u003c\/li\u003e\n\u003cli\u003eMercury\/Mariner V-175 DFI (2.5L), 2000 and up\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat engines does the Sierra 18-3606 thermostat kit fit?\u003c\/strong\u003e The Sierra 18-3606 fits Mercury\/Mariner V-135 DFI (2.5L) outboards from 1998 and up, V-150 DFI (2.5L) outboards from 1998 and up, and V-175 DFI (2.5L) outboards from 2000 and up.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat temperature is the 18-3606 thermostat rated for?\u003c\/strong\u003e It opens at 130 degrees F, which is the rating built into the Sierra 18-3606 Thermostat Kit for these Mercury\/Mariner DFI outboards.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat color is the thermostat housing?\u003c\/strong\u003e The Sierra 18-3606 kit has a white housing.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the 18-3606 thermostat kit weigh?\u003c\/strong\u003e This Sierra thermostat kit weighs 0.1 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-3606 an OEM-equivalent part?\u003c\/strong\u003e Sierra engineers the 18-3606 Thermostat Kit to meet or exceed the original equipment part it replaces, and Sierra supplies parts to OEM engine manufacturers and boat builders.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWill this thermostat work on any Mercury outboard?\u003c\/strong\u003e No, the Sierra 18-3606 is designed specifically for the Mercury\/Mariner V-135 DFI, V-150 DFI, and V-175 DFI (2.5L) outboards listed in its fitment; it is not a universal-fit thermostat.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the 18-3606 kit include a gasket or just the thermostat?\u003c\/strong\u003e The Sierra 18-3606 is sold as a Thermostat Kit rather than a standalone thermostat, packaged as a single unit under UPC 808282256784.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow do I know if my outboard needs a new thermostat?\u003c\/strong\u003e An outboard running hotter than normal, overheating, or showing erratic temperature gauge readings often points to a stuck or failed thermostat, which the Sierra 18-3606 is designed to replace on compatible V-135, V-150, and V-175 DFI engines.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-3606 genuine Sierra or a generic aftermarket part?\u003c\/strong\u003e It is a genuine Sierra-branded part, part number 18-3606, manufactured by Sierra rather than a third-party generic substitute.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is the difference between the V-135, V-150, and V-175 DFI fitment for this thermostat?\u003c\/strong\u003e All three engines use the same Sierra 18-3606 130F thermostat kit, but each engine has a different model-year starting point in the fitment: V-135 DFI and V-150 DFI from 1998 and up, and V-175 DFI from 2000 and up.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988154888411,"sku":"SIE-18-3606","price":137.6,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-3606_lg__97842.1753373158.500.750.jpg?v=1785189152"},{"product_id":"sierra-18-3605-thermostat-kit-for-mercury-v-135-v-150-v-175-dfi-2-5l-outboards-1998-up","title":"Sierra 18-3605 Thermostat Kit for Mercury 225\/250 EFI Outboard Engines","description":"\u003cp\u003eThe Sierra 18-3605 Thermostat Kit is a replacement thermostat kit built for Mercury 225\/250 EFI outboard engines within the serial number range 0G129222 to 0T408999. Sierra manufactures this kit to meet or exceed the specifications of the original equipment thermostat it replaces, giving boat owners and marine technicians a reliable option when servicing the cooling system on applicable Mercury EFI outboards.\u003c\/p\u003e\u003cp\u003eThe kit features a machined exterior finish and is compact in size, measuring 0.39 x 0.39 x 0.39 inches and weighing 0.13 pounds. It is identified by Sierra part number 18-3605 and UPC 808282265861, and it is covered under Sierra's manufacturer warranty for customer satisfaction.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-3605\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Type:\u003c\/strong\u003e Thermostat Kit\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Dimensions:\u003c\/strong\u003e 0.39 x 0.39 x 0.39 inches\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.13 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eExterior Finish:\u003c\/strong\u003e Machined\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 808282265861\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCategory:\u003c\/strong\u003e Mercury Outboard Thermostats \u0026amp; Gaskets\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\u003cli\u003eMercury 225\/250 EFI outboard engines, serial numbers 0G129222 to 0T408999\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat engines does the Sierra 18-3605 Thermostat Kit fit?\u003c\/strong\u003e The Sierra 18-3605 Thermostat Kit fits Mercury 225\/250 EFI outboard engines within the serial number range 0G129222 to 0T408999.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the 18-3605 a genuine Sierra part or an aftermarket replacement?\u003c\/strong\u003e It is an aftermarket thermostat kit manufactured by Sierra to meet or exceed the specifications of the original equipment thermostat it replaces.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is included with the 18-3605 kit?\u003c\/strong\u003e This part is sold as a complete Thermostat Kit for the applicable Mercury 225\/250 EFI outboard engines, identified by Sierra part number 18-3605.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat are the dimensions of the 18-3605 Thermostat Kit?\u003c\/strong\u003e The kit measures 0.39 x 0.39 x 0.39 inches.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the Sierra 18-3605 Thermostat Kit weigh?\u003c\/strong\u003e It weighs 0.13 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is the UPC for the Sierra 18-3605?\u003c\/strong\u003e The UPC for the Sierra 18-3605 Thermostat Kit is 808282265861.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes Sierra offer a warranty on the 18-3605 Thermostat Kit?\u003c\/strong\u003e Yes, the 18-3605 Thermostat Kit is covered under Sierra's manufacturer warranty for customer satisfaction.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat finish does the 18-3605 thermostat have?\u003c\/strong\u003e The thermostat has a machined exterior finish.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWill the 18-3605 fit other Mercury outboard models?\u003c\/strong\u003e The stated fitment for the 18-3605 Thermostat Kit is limited to Mercury 225\/250 EFI outboard engines with serial numbers 0G129222 to 0T408999; confirm your engine's serial number falls within this range before ordering.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat category does the 18-3605 belong to?\u003c\/strong\u003e The Sierra 18-3605 falls under the Mercury Outboard Thermostats \u0026amp; Gaskets category.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs there a specific OEM Mercury part number that the 18-3605 replaces?\u003c\/strong\u003e No specific OEM cross-reference number is listed for this kit; it is identified and ordered using Sierra part number 18-3605.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988154921179,"sku":"SIE-18-3605","price":82.77,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-3605_lg__65349.1558125952.500.750.jpg?v=1785187973"},{"product_id":"raw-water-thermostat-for-volvo-penta-replaces-oem-3587597-150f-sierra-18-3615","title":"Sierra Raw Water Thermostat 18-3615, 150 Degree F, White, Volvo Penta Applications","description":"\u003cp\u003eThe Sierra 18-3615 is a raw water thermostat designed to regulate engine cooling temperature in marine raw water cooling systems. Set to open at 150 degrees F (66 degrees C), it maintains consistent engine operating temperature by controlling the flow of raw water through the cooling circuit, helping protect the engine from overheating and from running too cool for efficient combustion. The thermostat is finished in white and is built to meet or exceed the specifications of the original equipment part it replaces. It is intended for raw water temperature control on Volvo Penta applications. Sierra manufactures replacement parts that supply many OEM engine manufacturers and boat builders, and the 18-3615 is produced to the same fit, form, and function standards as those OEM components. This thermostat is a straightforward maintenance replacement item for boat owners servicing their raw water cooling system, and it is backed by Sierra's standard limited warranty on parts purchased for marine engine upkeep.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-3615\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Name:\u003c\/strong\u003e Thermostat - Raw Water\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTemperature Rating:\u003c\/strong\u003e 150 degrees F (66 degrees C)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eColor:\u003c\/strong\u003e White\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSpecific Use:\u003c\/strong\u003e Raw Water Temperature Control for Volvo Penta Applications\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.12 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 808282270582\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cp\u003eDesigned for raw water temperature control on Volvo Penta applications.\u003c\/p\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat temperature does the Sierra 18-3615 thermostat open at?\u003c\/strong\u003e The Sierra 18-3615 raw water thermostat is rated to open at 150 degrees F (66 degrees C), which is the temperature at which it begins allowing raw water flow through the cooling circuit.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat color is the 18-3615 thermostat?\u003c\/strong\u003e It is white.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is the 18-3615 thermostat used for?\u003c\/strong\u003e The Sierra 18-3615 is used for raw water temperature control on Volvo Penta applications, regulating coolant flow to keep the engine operating within its intended temperature range.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the Sierra 18-3615 thermostat weigh?\u003c\/strong\u003e The Sierra 18-3615 raw water thermostat weighs 0.12 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-3615 an OEM or aftermarket part?\u003c\/strong\u003e It is a Sierra aftermarket replacement part engineered to meet or exceed the specifications of the original equipment thermostat it replaces.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the Sierra 18-3615 come with a warranty?\u003c\/strong\u003e Yes, the 18-3615 thermostat is covered under Sierra's standard limited warranty for marine replacement parts.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is the UPC for the Sierra 18-3615 thermostat?\u003c\/strong\u003e The UPC for the Sierra 18-3615 raw water thermostat is 808282270582.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan the Sierra 18-3615 be used as a routine cooling system replacement part?\u003c\/strong\u003e Yes, replacing a raw water thermostat like the Sierra 18-3615 during routine cooling system maintenance is a common way to keep engine operating temperature within its designed range.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the 18-3615 thermostat only for Volvo Penta engines?\u003c\/strong\u003e The Sierra 18-3615 is specified for raw water temperature control on Volvo Penta applications.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat does a raw water thermostat like the 18-3615 do?\u003c\/strong\u003e A raw water thermostat regulates the flow of raw water through the engine's cooling system, opening at a set temperature, in this case 150 degrees F, to prevent the engine from overheating or running too cold.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988155019483,"sku":"SIE-18-3615","price":22.67,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-3615__10374.1558188918.500.750.jpg?v=1785188161"},{"product_id":"sierra-18-3618-thermostat-kit-150f-raw-water-cooled-volvo-penta-i-o-cooling-system","title":"Sierra 18-3618 Raw Water Cooled Thermostat Kit, 150 Degree, Volvo Penta I\/O Cooling System","description":"\u003cp\u003eThe Sierra 18-3618 is a raw water cooled thermostat kit built for Volvo Penta I\/O engines that use a raw (open) cooling system, where river, lake, or sea water runs directly through the cylinder block. This kit uses a 150 degree Fahrenheit thermostat, which regulates the engine's operating temperature by controlling the flow of raw water through the cooling passages once the engine reaches that threshold. Maintaining the correct opening temperature protects against overheating in warm operating conditions while still allowing the engine to reach efficient running temperature quickly after startup.\u003c\/p\u003e\u003cp\u003eAs a raw water cooled thermostat, the 18-3618 is designed specifically for open cooling systems rather than closed (fresh water\/antifreeze) systems, so it is important to match the thermostat type to your engine's cooling configuration. The kit carries Sierra's part number 18-3618 and is intended as a direct fit for the Volvo Penta I\/O cooling system application it is listed for.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-3618\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Type:\u003c\/strong\u003e Thermostat Kit\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCooling System Type:\u003c\/strong\u003e Raw Water Cooled\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eThermostat Opening Temperature:\u003c\/strong\u003e 150 degrees Fahrenheit\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eApplication:\u003c\/strong\u003e I\/O - Volvo Penta Cooling System\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.12 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 808282270599\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\u003cli\u003eVolvo Penta I\/O engines with a raw water (open) cooling system, where raw water runs through the cylinder block\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat temperature thermostat is in the Sierra 18-3618 kit?\u003c\/strong\u003e The Sierra 18-3618 kit uses a 150 degree Fahrenheit thermostat, which opens at that temperature to regulate raw water flow through the engine.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the 18-3618 for a raw water or fresh water cooling system?\u003c\/strong\u003e It is a raw water cooled thermostat kit, meaning it is designed for open cooling systems where river, lake, or sea water runs directly through the cylinder block, not for closed fresh water\/antifreeze systems.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat engines does the Sierra 18-3618 fit?\u003c\/strong\u003e This thermostat kit is intended for Volvo Penta I\/O engines equipped with a raw water (open) cooling system.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the Sierra 18-3618 thermostat kit weigh?\u003c\/strong\u003e The 18-3618 thermostat kit weighs 0.12 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is the difference between the raw water and fresh water version of this thermostat?\u003c\/strong\u003e The raw water cooled version, part number 18-3618, is built for open cooling systems where outside water circulates through the engine block; a fresh water cooled version exists as a separate part number for closed cooling systems, so it is important to confirm which cooling system your engine uses before ordering.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is included in the Sierra 18-3618 kit?\u003c\/strong\u003e The 18-3618 is sold as a thermostat kit under Sierra part number 18-3618.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhy does the raw water cooling system need a thermostat at all?\u003c\/strong\u003e In a raw water (open) cooling system, the thermostat still regulates when raw water is allowed to flow through the cylinder block, helping the Volvo Penta I\/O engine reach and hold a stable operating temperature.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs Sierra 18-3618 a genuine Sierra part or an aftermarket equivalent?\u003c\/strong\u003e The 18-3618 is a Sierra branded thermostat kit, sold under Sierra's own part number for the Volvo Penta I\/O raw water cooling application.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat happens if I install the wrong opening temperature thermostat?\u003c\/strong\u003e Using a thermostat with the wrong opening temperature can cause the engine to run cooler or hotter than intended; the 18-3618 kit is specifically rated for a 150 degree Fahrenheit opening point for Volvo Penta I\/O raw water cooled applications.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan the 18-3618 be used on a closed (fresh water) cooling system?\u003c\/strong\u003e No, the 18-3618 is designated as a raw water cooled thermostat kit and is intended for open cooling systems where raw water runs through the cylinder block, not closed fresh water systems.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988155085019,"sku":"SIE-18-3618","price":26.02,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-3618__74888.1558188912.500.750.jpg?v=1785188914"},{"product_id":"sierra-18-3609-marine-thermostat-kit-for-yamaha-outboards-25-250-hp-replaces-yamaha-6e5-12411-30-00","title":"Sierra 18-3609 Thermostat Kit for Yamaha 2-Stroke Outboards, OEM 6J8-12414-A0-00, 60 Degrees C","description":"\u003cp\u003eThe Sierra 18-3609 Thermostat Kit is a complete cooling system replacement kit built for Yamaha 2-stroke outboard engines. Rather than sourcing a thermostat and gasket separately, this kit bundles both components so the cooling system can be serviced in a single step. It is engineered to meet or exceed the performance of the original equipment part it replaces, giving boat owners a dependable way to restore proper engine temperature regulation.\u003c\/p\u003e\u003cp\u003eInside the kit is one 18-3541 thermostat, cross-referenced to Yamaha OEM number 66M-12411-01-00, and one 18-0835 cover gasket, cross-referenced to Yamaha OEM number 62Y-12414-00-00. Together these components correspond to the Yamaha OEM kit equivalent 6J8-12414-A0-00. The thermostat is rated to open at 60 degrees C, matching the factory-specified opening temperature for the cooling systems this kit is designed to service.\u003c\/p\u003e\u003cp\u003eA worn or stuck thermostat is a common cause of an overheating outboard, and the included gasket ensures a proper seal is restored at the same time the thermostat is replaced, preventing coolant leaks and repeat labor. This kit is intended for Yamaha 2-stroke outboard cooling systems.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-3609\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Type:\u003c\/strong\u003e Thermostat Kit\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTemperature Rating:\u003c\/strong\u003e 60 degrees C\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eKit Contents:\u003c\/strong\u003e (1) 18-3541 Thermostat, (1) 18-0835 Cover Gasket\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eThermostat OEM Cross Reference:\u003c\/strong\u003e 66M-12411-01-00\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eGasket OEM Cross Reference:\u003c\/strong\u003e 62Y-12414-00-00\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eKit OEM Cross Reference:\u003c\/strong\u003e 6J8-12414-A0-00\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eEngine Type:\u003c\/strong\u003e 2-Stroke\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eApplication:\u003c\/strong\u003e Yamaha Outboard Cooling System\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.09 pounds\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\u003cli\u003eYamaha 2-stroke outboard cooling systems\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e6J8-12414-A0-00\u003c\/li\u003e\n\u003cli\u003e66M-12411-01-00\u003c\/li\u003e\n\u003cli\u003e62Y-12414-00-00\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat does the Sierra 18-3609 thermostat kit include?\u003c\/strong\u003e The kit includes one 18-3541 thermostat and one 18-0835 cover gasket, giving you both parts needed to service a Yamaha 2-stroke outboard cooling system in a single purchase.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat temperature does the 18-3609 thermostat open at?\u003c\/strong\u003e The thermostat included in the Sierra 18-3609 kit is rated to open at 60 degrees C, which matches the factory cooling system specification it is designed to service.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-3609 an OEM-equivalent part?\u003c\/strong\u003e Yes. The Sierra 18-3609 kit cross-references to Yamaha OEM kit number 6J8-12414-A0-00, with the individual thermostat matching OEM number 66M-12411-01-00 and the gasket matching OEM number 62Y-12414-00-00.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhich engines is the 18-3609 thermostat kit designed for?\u003c\/strong\u003e This kit is designed for Yamaha 2-stroke outboard cooling systems.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDo I need to replace the gasket along with the thermostat?\u003c\/strong\u003e Yes, replacing both together is recommended, which is why the 18-3609 kit bundles the 18-3541 thermostat with the 18-0835 cover gasket rather than selling the thermostat alone.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the 18-3609 thermostat kit weigh?\u003c\/strong\u003e The Sierra 18-3609 thermostat kit weighs 0.09 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat OEM part numbers does the 18-3609 kit replace?\u003c\/strong\u003e The 18-3609 kit corresponds to Yamaha OEM numbers 6J8-12414-A0-00 (kit), 66M-12411-01-00 (thermostat), and 62Y-12414-00-00 (gasket).\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan a failed thermostat cause my outboard to overheat?\u003c\/strong\u003e A stuck or worn thermostat is a common cause of outboard overheating, which is why the 18-3609 kit is designed to restore correct temperature regulation with a fresh, properly rated 60 degree C thermostat.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes Sierra manufacture this part to OEM standards?\u003c\/strong\u003e Sierra products, including the 18-3609 kit, are engineered to meet or exceed the performance of the original equipment part they replace.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the 18-3609 a two-stroke or four-stroke application?\u003c\/strong\u003e The Sierra 18-3609 thermostat kit is built for Yamaha 2-stroke outboard cooling systems.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988155150555,"sku":"SIE-18-3609","price":27.14,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-3609_lg__60638.1558126140.500.750.jpg?v=1785188422"},{"product_id":"marine-thermostat-kit-for-yamaha-outboards-replaces-6e5-12411-30-00-and-688-12414-a1-00-fits-f15-f25-f30-f40-f50-f60-t9-9-t25-t50-t60-140f-60c-mpn-18-3611","title":"Sierra 18-3611 Thermostat Kit for Yamaha F15-F60, T9.9-T60 Outboards, Replaces 6E5-12411-30-00","description":"\u003cp\u003eThe Sierra 18-3611 Thermostat Kit is a complete cooling-system repair kit for compatible Yamaha outboard engines, pairing a 140 degree F (60 degree C) thermostat with its matching gasket in one package. The thermostat regulates engine coolant flow to keep the powerhead within its designed operating temperature range, opening at 140 degrees F to allow water flow once the engine reaches operating temperature and helping prevent overheating or over-cooling that can accelerate wear on internal components. The included gasket seals the thermostat housing to prevent coolant leaks after installation. Sierra engineers this kit to meet or exceed the specifications of the original equipment parts it replaces, and Sierra supplies OEM engine manufacturers and boat builders with parts on a daily basis, so the fit and function match what the engine was originally designed around. This kit fits a broad range of Yamaha outboard models, including the 15, F15, F25, F30, F40, F50, F60, F9.9, T25, T50, T60, and T9.9. Because thermostat failure is a common cause of overheating alarms and inconsistent engine temperature, replacing both the thermostat and gasket together, as this kit allows, is the recommended approach rather than reusing an old gasket. The kit is a straightforward maintenance item for routine cooling system service or as a repair when overheating symptoms appear.\u003c\/p\u003e\u003ch3\u003eSpecifications\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Sierra\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number:\u003c\/strong\u003e 18-3611\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Type:\u003c\/strong\u003e Thermostat Kit\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eThermostat Temperature Rating:\u003c\/strong\u003e 140 degrees F \/ 60 degrees C\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eKit Contents:\u003c\/strong\u003e 1 thermostat (Sierra 18-3540), 1 gasket (Sierra 18-0844)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.08 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 808282265540\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eYamaha 15 (2006)\u003c\/li\u003e\n\u003cli\u003eYamaha F15 (1998-06)\u003c\/li\u003e\n\u003cli\u003eYamaha F25 (1999-06)\u003c\/li\u003e\n\u003cli\u003eYamaha F30 (2001-06)\u003c\/li\u003e\n\u003cli\u003eYamaha F40 (1999-06)\u003c\/li\u003e\n\u003cli\u003eYamaha F50 (1996-06)\u003c\/li\u003e\n\u003cli\u003eYamaha F60 (2002-06)\u003c\/li\u003e\n\u003cli\u003eYamaha F9.9 (2005-06)\u003c\/li\u003e\n\u003cli\u003eYamaha T25 (2001-06)\u003c\/li\u003e\n\u003cli\u003eYamaha T50 (1996-06)\u003c\/li\u003e\n\u003cli\u003eYamaha T60 (2003-06)\u003c\/li\u003e\n\u003cli\u003eYamaha T9.9 (2005-06)\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e6E5-12411-30-00 (thermostat)\u003c\/li\u003e\n\u003cli\u003e688-12414-A1-00 (gasket)\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat temperature does the Sierra 18-3611 thermostat open at?\u003c\/strong\u003e It opens at 140 degrees F (60 degrees C), which is the temperature rating specified for the thermostat included in the Sierra 18-3611 kit.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is included in the 18-3611 kit?\u003c\/strong\u003e The kit contains one thermostat and one matching gasket, so you can replace both parts together during a single service on compatible Yamaha outboards.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhich Yamaha outboard models does the 18-3611 thermostat kit fit?\u003c\/strong\u003e It fits the Yamaha 15 (2006), F15 (1998-06), F25 (1999-06), F30 (2001-06), F40 (1999-06), F50 (1996-06), F60 (2002-06), F9.9 (2005-06), T25 (2001-06), T50 (1996-06), T60 (2003-06), and T9.9 (2005-06).\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes this kit include the gasket, or do I need to buy it separately?\u003c\/strong\u003e The gasket is included in the Sierra 18-3611 kit along with the thermostat, so no separate gasket purchase is needed for a standard replacement.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat OEM part numbers does the Sierra 18-3611 kit replace?\u003c\/strong\u003e The kit's components correspond to OEM numbers 6E5-12411-30-00 for the thermostat and 688-12414-A1-00 for the gasket.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-3611 an OEM part or an aftermarket equivalent?\u003c\/strong\u003e It is an aftermarket kit manufactured by Sierra, engineered to meet or exceed the specifications of the original equipment thermostat and gasket it replaces.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the 18-3611 thermostat kit weigh?\u003c\/strong\u003e The complete kit weighs 0.08 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWill this thermostat kit fit a Yamaha F50 outboard?\u003c\/strong\u003e Yes, the Sierra 18-3611 kit is listed as fitting the Yamaha F50 for model years 1996 through 2006.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhen should the thermostat and gasket be replaced?\u003c\/strong\u003e Both parts in the 18-3611 kit are typically replaced together whenever the thermostat is serviced, since the gasket should not be reused once the housing has been opened.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is the UPC for the Sierra 18-3611 kit?\u003c\/strong\u003e The UPC is 808282265540.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the kit fit the Yamaha T9.9 outboard?\u003c\/strong\u003e Yes, the Sierra 18-3611 thermostat kit lists compatibility with the Yamaha T9.9 for model years 2005 through 2006.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat brand manufactures the 18-3611 thermostat kit?\u003c\/strong\u003e Sierra manufactures the 18-3611 thermostat kit.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988155183323,"sku":"SIE-18-3611","price":37.82,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-3611_lg__62134.1558126251.500.750.jpg?v=1785188091"}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/collections\/EMP_75-03222_MerCruiser_Thermostat_Kit__58012.1722504328.500.750.jpg?v=1785356503","url":"https:\/\/www.goodvibesmarina.com\/collections\/gvcat-engine-parts-systems-cooling-system-thermostats-housings.oembed?page=2","provider":"Good Vibes Marina","version":"1.0","type":"link"}