{"product_id":"marine-engine-thermostat-for-mercruiser-496-mag-ho-8-1l-mie-replaces-indmar-s985009-sierra-18-43017","title":"Sierra Thermostat 18-43017, Replaces Indmar S985009, Fits Mercruiser 496 Mag \u0026 HO, 8.1L MIE \u0026 HO, Pack of 2","description":"\u003cp\u003eThe Sierra 18-43017 is a replacement marine engine thermostat sold as a package of 2, giving boat owners a matched pair on hand for a complete cooling system service. It is manufactured to replace Indmar S985009 and is built for the closed cooling systems used on Mercruiser 496 Mag \u0026amp; HO engines and 8.1L MIE \u0026amp; HO engines, where consistent thermostat performance is critical to keeping engine operating temperature within the manufacturer's designed range.\u003c\/p\u003e\u003cp\u003eA marine thermostat like the 18-43017 regulates coolant flow by opening and closing in response to engine temperature, preventing overheating during operation and helping the engine reach proper operating temperature more quickly after startup. Replacing a worn or stuck thermostat is a routine part of marine engine cooling system maintenance and is commonly done alongside a gasket change during a full thermostat service. Because the 18-43017 is sold two to a package, it is a convenient option for owners servicing twin-engine boats or keeping a spare on board.\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 18-43017\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Type:\u003c\/strong\u003e Thermostat\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePackage Quantity:\u003c\/strong\u003e Pack of 2 (priced per package)\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 808282341985\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eMercruiser 496 Mag \u0026amp; HO\u003c\/li\u003e\n\u003cli\u003eMercruiser 8.1L MIE \u0026amp; HO\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\u003cli\u003eIndmar S985009\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat engines does the Sierra 18-43017 thermostat fit?\u003c\/strong\u003e The Sierra 18-43017 thermostat fits Mercruiser 496 Mag \u0026amp; HO engines and Mercruiser 8.1L MIE \u0026amp; HO engines.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat OEM part number does the 18-43017 replace?\u003c\/strong\u003e The Sierra 18-43017 replaces Indmar S985009, so it can be used as a direct equivalent on applicable engines.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow many thermostats come in one package of 18-43017?\u003c\/strong\u003e Two thermostats are included in each package of the Sierra 18-43017, and the item is priced per package of 2.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the Sierra 18-43017 thermostat weigh?\u003c\/strong\u003e Each package of the Sierra 18-43017 weighs 0.15 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is the UPC for the Sierra 18-43017?\u003c\/strong\u003e The UPC for the Sierra 18-43017 thermostat is 808282341985.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs a gasket included with the Sierra 18-43017 thermostat?\u003c\/strong\u003e No, the Sierra 18-43017 package includes the thermostats only; a matching thermostat gasket should be ordered separately when servicing the cooling system.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhy would I replace a marine engine thermostat like the 18-43017?\u003c\/strong\u003e A marine thermostat regulates coolant flow to keep the engine at its proper operating temperature, and a worn or stuck unit like those replaced by the 18-43017 can cause overheating or slow warm-up, making periodic replacement part of routine cooling system maintenance.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan I use the 18-43017 on a single-engine boat if it comes as a pack of 2?\u003c\/strong\u003e Yes, the Sierra 18-43017 is sold as a package of 2 thermostats, which works well for single-engine boats needing a spare on hand or for twin-engine boats being serviced at the same time.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-43017 an OEM or aftermarket thermostat?\u003c\/strong\u003e The Sierra 18-43017 is an aftermarket replacement thermostat manufactured to replace the OEM Indmar S985009 part on applicable Mercruiser engines.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat category of product is the Sierra 18-43017?\u003c\/strong\u003e The Sierra 18-43017 is a marine engine thermostat used in the cooling system of Mercruiser 496 Mag \u0026amp; HO and 8.1L MIE \u0026amp; HO engines.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988178448603,"sku":"SIE-18-43017","price":23.55,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/18-43017__43351.1737896496.500.750.jpg?v=1785189165","url":"https:\/\/www.goodvibesmarina.com\/products\/marine-engine-thermostat-for-mercruiser-496-mag-ho-8-1l-mie-replaces-indmar-s985009-sierra-18-43017","provider":"Good Vibes Marina","version":"1.0","type":"link"}