{"product_id":"sierra-18-3646-marine-thermostat-kit-140f-replaces-mercruiser-807252q3-fits-ford-gm-v-8-standard-closed-cooling","title":"Sierra 18-3646 Thermostat Kit, 140F, Replaces GM 4765100, Fits 228\/305 V-8 1977-1982","description":"\u003cp\u003eThe Sierra 18-3646 Thermostat Kit is a complete cooling-system repair kit built around a 140 degree F thermostat for GM 228\/305 cubic inch V-8 marine engines produced 1977-1982. Rather than supplying just the thermostat, the kit bundles every gasket needed to reseal the housing during replacement, so the job can be completed in one pass without having to source individual gaskets separately. The thermostat is manufactured to meet or exceed the specifications of the original equipment part it replaces, making it a straightforward drop-in for engines using the housing and drain configuration covered by this part number.\u003c\/p\u003e\u003cp\u003eBecause marine cooling systems rely on the thermostat opening at the correct temperature to regulate engine operating temperature, using the correct 140 degree F unit for this engine family helps maintain proper heat management and protect against overheating or over-cooling. The kit is intended for engine cooling system service and is a routine maintenance item that should be replaced any time cooling performance is in question or during a scheduled overhaul.\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 18-3646\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Type:\u003c\/strong\u003e Thermostat Kit\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eThermostat Opening Temperature:\u003c\/strong\u003e 140 degrees F\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMaterial:\u003c\/strong\u003e Copper\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.15 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 808282100919\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eKit Contents:\u003c\/strong\u003e Thermostat (18-3551), Thermostat Cover Gasket (18-2553), Thermostat Cover Gasket (18-2834), Thermostat Gasket (18-2844), Thermostat Gasket (18-2917)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFitment:\u003c\/strong\u003e GM 228\/305 cubic inch V-8 engines, 1977-1982\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\u003cli\u003eGM 228\/305 cubic inch 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\u003cli\u003e18-1993\u003c\/li\u003e\n\u003cli\u003e18-1977-1\u003c\/li\u003e\n\u003cli\u003e18-3551\u003c\/li\u003e\n\u003cli\u003e18-2844\u003c\/li\u003e\n\u003cli\u003e18-0398\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat temperature does the Sierra 18-3646 thermostat open at?\u003c\/strong\u003e 140 degrees F is the opening temperature for the thermostat included in the Sierra 18-3646 Thermostat Kit.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is included in the Sierra 18-3646 Thermostat Kit?\u003c\/strong\u003e The kit contains a 140 degree F thermostat (18-3551) along with four gaskets: two thermostat cover gaskets (18-2553 and 18-2834) and two thermostat gaskets (18-2844 and 18-2917), covering everything needed to reseal the housing during replacement.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhich engines does the 18-3646 thermostat kit fit?\u003c\/strong\u003e This kit is built for GM 228\/305 cubic inch V-8 engines from 1977-1982.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat OEM part numbers does the 18-3646 kit replace?\u003c\/strong\u003e The Sierra 18-3646 Thermostat Kit replaces OEM numbers 4765100, 6218461, 18-1993, 18-1977-1, 18-3551, 18-2844, and 18-0398.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-3646 a genuine OEM part or an aftermarket replacement?\u003c\/strong\u003e It is an aftermarket replacement manufactured by Sierra to meet or exceed the specifications of the original equipment thermostat it replaces.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the thermostat kit weigh?\u003c\/strong\u003e The Sierra 18-3646 Thermostat Kit weighs 0.15 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDo I need to buy separate gaskets when replacing the thermostat?\u003c\/strong\u003e No, the 18-3646 kit already includes the two thermostat cover gaskets and two thermostat gaskets needed to complete the reseal, so no additional gaskets are required.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat material is the thermostat made from?\u003c\/strong\u003e The thermostat in the Sierra 18-3646 kit is made of copper.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan this kit be cross-referenced by GM part number 4765100?\u003c\/strong\u003e Yes, GM part number 4765100 is one of the OEM numbers that the Sierra 18-3646 Thermostat Kit replaces.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is the UPC for the Sierra 18-3646 Thermostat Kit?\u003c\/strong\u003e The UPC for this kit is 808282100919.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988156625115,"sku":"SIE-18-3646","price":27.21,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/18-3646__86999.1739458718.500.750.jpg?v=1785188316","url":"https:\/\/www.goodvibesmarina.com\/products\/sierra-18-3646-marine-thermostat-kit-140f-replaces-mercruiser-807252q3-fits-ford-gm-v-8-standard-closed-cooling","provider":"Good Vibes Marina","version":"1.0","type":"link"}