{"product_id":"thermostat-cover-gasket-for-mercury-200-250hp-3-0l-dfi-efi-outboard-replaces-27-850318-sierra-18-3675","title":"Sierra 18-3675 Thermostat Gasket, Replaces Mercury 27-854961","description":"\u003cp\u003eThe Sierra 18-3675 Thermostat Gasket is a replacement gasket engineered to seal the thermostat housing on applicable Mercury outboard engines. It creates the seal between the thermostat cover and the powerhead, preventing coolant leaks and ensuring the cooling system holds pressure correctly during operation. As a direct cross-reference for several Mercury Marine OEM part numbers, this gasket is built to match original factory dimensions and sealing surfaces, so it installs in place of the OEM part without modification.\u003c\/p\u003e\u003cp\u003eSierra manufactures its gaskets to meet or exceed the specifications of the original equipment they replace, giving boat owners and marine technicians a reliable option for routine thermostat service, cooling system maintenance, or full thermostat housing rebuilds. The gasket is compact and lightweight, shipping as a single unit ready to drop into place during a thermostat swap or cover reseal.\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 18-3675\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 27-854961, 27-85496, 27-64204, 27-72508\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eColor:\u003c\/strong\u003e Black\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 808282145262\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.01 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePackage Height:\u003c\/strong\u003e 7.37 centimeters\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePackage Length:\u003c\/strong\u003e 7.62 centimeters\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePackage Width:\u003c\/strong\u003e 6.86 centimeters\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCountry of Origin:\u003c\/strong\u003e China\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUnit Count:\u003c\/strong\u003e 1\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e27-854961\u003c\/li\u003e\n\u003cli\u003e27-85496\u003c\/li\u003e\n\u003cli\u003e27-64204\u003c\/li\u003e\n\u003cli\u003e27-72508\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat is the Sierra 18-3675 used for?\u003c\/strong\u003e The Sierra 18-3675 is a thermostat gasket that seals the thermostat housing cover on the powerhead, sealing the cooling system so coolant does not leak past the cover during operation.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhich OEM part numbers does 18-3675 replace?\u003c\/strong\u003e It cross-references to Mercury Marine part numbers 27-854961, 27-85496, 27-64204, and 27-72508, so any of those OEM numbers can be replaced with Sierra 18-3675.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs this a genuine Sierra part or an aftermarket copy?\u003c\/strong\u003e Sierra 18-3675 is a Sierra-manufactured replacement part, built to meet or exceed the specifications of the original equipment gasket it replaces.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the 18-3675 gasket weigh?\u003c\/strong\u003e The Sierra 18-3675 thermostat gasket weighs 0.01 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat color is the Sierra 18-3675 gasket?\u003c\/strong\u003e It is black.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is included when I order this part?\u003c\/strong\u003e Ordering Sierra 18-3675 gets you one thermostat gasket; the unit count for this listing is 1.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhere is the Sierra 18-3675 manufactured?\u003c\/strong\u003e The country of origin for the Sierra 18-3675 gasket is China.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan I use 18-3675 for a thermostat replacement or housing rebuild?\u003c\/strong\u003e Yes, the gasket is intended for thermostat service and reseal work at the thermostat housing cover, including full thermostat replacement jobs.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat are the package dimensions of the 18-3675 gasket?\u003c\/strong\u003e The package measures 7.37 centimeters in height, 7.62 centimeters in length, and 6.86 centimeters in width.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes Sierra 18-3675 come with a UPC for retail tracking?\u003c\/strong\u003e Yes, the UPC for Sierra 18-3675 is 808282145262.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the 18-3675 gasket reusable once removed?\u003c\/strong\u003e Gaskets are designed as a single-use seal; Sierra 18-3675 should be replaced with a new gasket any time the thermostat cover is removed to ensure a proper seal.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988161245403,"sku":"SIE-18-3675","price":3.02,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-3675_lg__06827.1709755655.500.750.jpg?v=1785188248","url":"https:\/\/www.goodvibesmarina.com\/products\/thermostat-cover-gasket-for-mercury-200-250hp-3-0l-dfi-efi-outboard-replaces-27-850318-sierra-18-3675","provider":"Good Vibes Marina","version":"1.0","type":"link"}