{"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","url":"https:\/\/www.goodvibesmarina.com\/products\/sierra-18-2554-9-thermostat-cover-gasket-2-pack-replaces-mercruiser-27-41812-fits-mercruiser-gm-v-6-v-8","provider":"Good Vibes Marina","version":"1.0","type":"link"}