{"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","url":"https:\/\/www.goodvibesmarina.com\/products\/thermostat-cover-gasket-for-mercruiser-4-cylinder-engines-replaces-27-896561-27-89656-sierra-18-2831-9-pack-of-2","provider":"Good Vibes Marina","version":"1.0","type":"link"}