{"product_id":"sierra-18-2946-marine-head-gasket-for-gm-181-cid-3-0l-replaces-mercruiser-27-52364-chris-craft-16-50-00204","title":"Sierra 18-2946 Head Gasket - Replaces 16.50-00204 for GM 181 CID (3.0L) Marine Engines","description":"\u003cp\u003eThe Sierra 18-2946 Head Gasket is a marine-grade replacement gasket engineered for GM 181 CID (3.0L) engines used in stern drive and inboard marine applications. It is designed to seal the mating surface between the cylinder head and engine block, maintaining proper compression, coolant containment, and oil control under the sustained heat and vibration cycles typical of marine service. Using a gasket built specifically for the marine environment, rather than an automotive substitute, helps ensure a reliable, long-term seal against the corrosion and thermal stress that saltwater and freshwater cooling systems introduce.\u003c\/p\u003e\u003cp\u003eThe 18-2946 is a direct fit for GM 181 CID (3.0L) engines and is a cross-reference match for the OEM 16.50-00204 gasket, allowing it to be installed as a like-for-like replacement during a head gasket service, engine rebuild, or head removal for valve or manifold work. Each Sierra product is built to meet or exceed the performance of the original equipment part it replaces, giving boat owners and marine technicians a dependable option when the factory gasket has failed or the engine is being serviced.\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 18-2946\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eReplaces (OEM Cross-Reference):\u003c\/strong\u003e 16.50-00204\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFitment:\u003c\/strong\u003e GM 181 CID Engine (3.0L)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.61 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eColor:\u003c\/strong\u003e White\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUnit Count:\u003c\/strong\u003e 1\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\u003cli\u003eGM 181 CID Engine (3.0L)\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\u003cli\u003e16.50-00204\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat engine does the Sierra 18-2946 head gasket fit?\u003c\/strong\u003e The 18-2946 head gasket is designed for GM 181 CID (3.0L) marine engines.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the 18-2946 a direct OEM replacement?\u003c\/strong\u003e Yes, it directly replaces OEM part number 16.50-00204 and is built to meet or exceed the original equipment part's performance.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the 18-2946 head gasket weigh?\u003c\/strong\u003e It weighs 0.61 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat color is the Sierra 18-2946 head gasket?\u003c\/strong\u003e It is white.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow many gaskets come in a package of the 18-2946?\u003c\/strong\u003e The 18-2946 is sold as a single-unit head gasket, with a unit count of 1.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan the 18-2946 be used on other GM engine sizes like the 305 or 350 CID?\u003c\/strong\u003e No, the 18-2946 is specified for GM 181 CID (3.0L) engines; larger GM 305\/350 and 454 CID engines use different Sierra head gasket part numbers.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the 18-2946 require any special gasket sealant during installation?\u003c\/strong\u003e A dedicated gasket sealant is recommended for proper installation of the 18-2946, though the sealant itself is a separate product.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the 18-2946 suitable for both engine rebuilds and single head gasket replacement jobs?\u003c\/strong\u003e Yes, this Sierra head gasket can be used for a full engine rebuild or a standalone head gasket replacement on a GM 181 CID (3.0L) engine.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat OEM part number does the 18-2946 cross-reference to?\u003c\/strong\u003e It cross-references to OEM number 16.50-00204.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-2946 a genuine OEM part or an aftermarket equivalent?\u003c\/strong\u003e The 18-2946 is a Sierra-manufactured aftermarket gasket engineered to meet or exceed the performance of the original 16.50-00204 OEM gasket it replaces.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988135325915,"sku":"SIE-18-2946","price":109.58,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-2946_lg__51286.1558124415.500.750.jpg?v=1785187988","url":"https:\/\/www.goodvibesmarina.com\/products\/sierra-18-2946-marine-head-gasket-for-gm-181-cid-3-0l-replaces-mercruiser-27-52364-chris-craft-16-50-00204","provider":"Good Vibes Marina","version":"1.0","type":"link"}