{"product_id":"sierra-18-3863-head-gasket-for-mercury-mariner-135-150-hp-outboards-replaces-oem-27-96542-1","title":"Sierra 18-3863 Head Gasket for Mercury 150 MAR V-6 Outboard Motors","description":"\u003cp\u003eThe Sierra 18-3863 is a round head gasket built for Mercury 150 MAR V-6 outboard motors, specifically the production run covering serial numbers 6038681 through C239553. As a critical seal between the cylinder head and powerhead block, the head gasket prevents the loss of compression and keeps combustion gases, fuel, and coolant properly contained within their intended passages. A worn, cracked, or improperly seated head gasket can lead to compression loss, overheating, or coolant intrusion into the cylinders, making this a key maintenance and rebuild component for outboard owners performing a top-end service or full powerhead rebuild.\u003c\/p\u003e\u003cp\u003eSierra manufactures this gasket to meet or exceed the specifications of the original equipment part it replaces, and it is engineered to hold up to the demands of high-horsepower marine engines operating in a harsh saltwater or freshwater environment. The gasket ships as a single round unit finished in white and is intended as a direct fit for the specific Mercury 150 MAR V-6 serial number range noted above, so confirming your engine's serial number against that range before ordering is recommended. Every Sierra part carries the backing of Sierra's customer satisfaction warranty program.\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 18-3863\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Category:\u003c\/strong\u003e Mercury Outboard Head Gasket\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFitment:\u003c\/strong\u003e Mercury 150 MAR V-6 outboard, serial numbers 6038681 to C239553\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCylinder Configuration:\u003c\/strong\u003e V-6\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eShape:\u003c\/strong\u003e Round\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eColor:\u003c\/strong\u003e White\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 030999753717\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUnit Count:\u003c\/strong\u003e 1\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight:\u003c\/strong\u003e 0.18 pounds\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\u003cli\u003eMercury 150 MAR, V-6, serial numbers 6038681 to C239553\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat engine does the Sierra 18-3863 head gasket fit?\u003c\/strong\u003e The 18-3863 is designed for Mercury 150 MAR V-6 outboard motors within the serial number range 6038681 to C239553. Checking your outboard's serial number against that range confirms this is the correct gasket for your engine.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow do I know if my serial number is in range for the 18-3863 gasket?\u003c\/strong\u003e Your Mercury 150 MAR outboard's serial number needs to fall between 6038681 and C239553 for the 18-3863 head gasket to be the correct fit; engines outside that range use a different Sierra head gasket part number.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat shape and color is this head gasket?\u003c\/strong\u003e The Sierra 18-3863 is a round head gasket finished in white.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the 18-3863 head gasket weigh?\u003c\/strong\u003e It weighs 0.18 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-3863 an OEM part or an aftermarket replacement?\u003c\/strong\u003e The 18-3863 is a Sierra-manufactured replacement gasket engineered to meet or exceed the specifications of the original equipment part it replaces, rather than a part sourced directly from Mercury.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow many gaskets come in the package?\u003c\/strong\u003e One Sierra 18-3863 head gasket ships per unit.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the 18-3863 come with a warranty?\u003c\/strong\u003e Yes, the 18-3863 head gasket is covered under Sierra's customer satisfaction warranty program, as are all Sierra parts.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is a head gasket used for on a Mercury outboard?\u003c\/strong\u003e On a Mercury 150 MAR V-6, the head gasket seals the junction between the cylinder head and the powerhead block, containing compression and preventing combustion gases, fuel, or coolant from leaking between passages.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat are signs I need to replace the 18-3863 head gasket?\u003c\/strong\u003e Loss of engine compression, overheating, or coolant finding its way into the cylinders on a Mercury 150 MAR V-6 are typical indicators that the head gasket, such as the Sierra 18-3863, needs replacement.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan I use the 18-3863 gasket on a Mercury 150 MAR outside the listed serial range?\u003c\/strong\u003e No, the 18-3863 is matched to the Mercury 150 MAR V-6 serial number range 6038681 to C239553; outboards with serial numbers outside that range require a different head gasket part number.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988168618203,"sku":"SIE-18-3863","price":37.7,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-3863_lg__67357.1558125418.500.750.jpg?v=1785189038","url":"https:\/\/www.goodvibesmarina.com\/products\/sierra-18-3863-head-gasket-for-mercury-mariner-135-150-hp-outboards-replaces-oem-27-96542-1","provider":"Good Vibes Marina","version":"1.0","type":"link"}