{"product_id":"sierra-18-0721-open-dry-joint-riser-gasket-replaces-mercruiser-27-864547a02-fits-4-3l-5-0l-5-7l-6-2l-dry-joint-manifold-and-riser","title":"Sierra 18-0721 Open Dry-Joint Exhaust Gasket, Replaces Mercruiser 27-864547A02\/27-864547A01, Fits 4.3L Alpha\/Bravo 2002 and Newer","description":"\u003cp\u003eThe Sierra 18-0721 is an Open-style dry-joint exhaust gasket engineered as a direct replacement for the original equipment gasket on MerCruiser 4.3L Alpha\/Bravo sterndrive applications built 2002 and newer without engine catalyst. Dry-joint gaskets seal the mating surface between the exhaust manifold and riser, and choosing the correct style matters: this is the Open variant, part of a three-style family (Open, Closed, and Restricted) that all share a common mounting footprint but differ in how they route exhaust flow. Installing the wrong style can affect engine cooling and exhaust backpressure, so confirming 18-0721 against your existing gasket or manufacturer reference before ordering is important.\u003c\/p\u003e\u003cp\u003eThis gasket is round in shape and finished in white, and is sold as a single unit for one exhaust joint. It directly replaces the Mercruiser OEM gasket numbers 27-864547A02 and 27-864547A01, so it can be used as a drop-in service part during manifold or riser replacement, tune-up, or routine maintenance where the old dry-joint seal has failed or is showing signs of leakage or corrosion. Sierra manufactures the 18-0721 to meet or exceed the specifications of the original equipment part it replaces, making it a reliable choice for engine and drive maintenance in the demanding marine environment.\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 18-0721\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eItem Type:\u003c\/strong\u003e Dry Joint Gasket (Open)\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\u003eWeight:\u003c\/strong\u003e 0.25 pounds\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUPC:\u003c\/strong\u003e 808282359454\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFits:\u003c\/strong\u003e 4.3L Alpha\/Bravo (2002 and newer without engine catalyst)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRelated Gasket Styles:\u003c\/strong\u003e 18-0720 (Closed), 18-0722 (Restricted)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eReplaces (OEM):\u003c\/strong\u003e 27-864547A02, 27-864547A01\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFitment\u003c\/h3\u003e\u003cul\u003e\u003cli\u003eMercruiser 4.3L Alpha\/Bravo sterndrive, 2002 and newer, without engine catalyst\u003c\/li\u003e\u003c\/ul\u003e\u003ch3\u003eReplaces (OEM)\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e27-864547A02\u003c\/li\u003e\n\u003cli\u003e27-864547A01\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eWhat does the Sierra 18-0721 gasket fit?\u003c\/strong\u003e The 18-0721 is designed for MerCruiser 4.3L Alpha\/Bravo sterndrive applications built 2002 and newer without engine catalyst.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat OEM part numbers does the 18-0721 replace?\u003c\/strong\u003e It replaces Mercruiser 27-864547A02 and 27-864547A01, making it a direct swap for either of those original equipment gasket numbers.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs 18-0721 the Open, Closed, or Restricted dry-joint gasket?\u003c\/strong\u003e 18-0721 is the Open-style dry-joint gasket. Sierra also offers 18-0720 as the Closed style and 18-0722 as the Restricted style for the same joint.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow much does the 18-0721 gasket weigh?\u003c\/strong\u003e The gasket weighs 0.25 pounds.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat color and shape is the 18-0721 gasket?\u003c\/strong\u003e It is round in shape and white in color.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the 18-0721 come with mounting hardware?\u003c\/strong\u003e The 18-0721 is sold as a single gasket unit; it does not include the manifold, riser, or fastening hardware.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow do I know if I need the Open, Closed, or Restricted version?\u003c\/strong\u003e Match the style to the gasket currently installed or to your manifold and riser specification, since 18-0720, 18-0721, and 18-0722 share a mounting footprint but route exhaust flow differently.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eIs the Sierra 18-0721 genuine OEM or aftermarket?\u003c\/strong\u003e The 18-0721 is a Sierra-manufactured replacement part, built to meet or exceed the specifications of the Mercruiser 27-864547A02\/27-864547A01 gasket it replaces.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWill 18-0721 fit a 4.3L engine with a catalyst-equipped exhaust?\u003c\/strong\u003e No, this gasket is specified for 4.3L Alpha\/Bravo applications 2002 and newer without engine catalyst.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat is the UPC for the Sierra 18-0721?\u003c\/strong\u003e The UPC for Sierra 18-0721 is 808282359454.\u003c\/p\u003e","brand":"Sierra","offers":[{"title":"Default Title","offer_id":48988085616859,"sku":"SIE-18-0721","price":65.35,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0839\/7586\/4539\/files\/SIE-18-0721__80767.1713451370.500.750.jpg?v=1785188213","url":"https:\/\/www.goodvibesmarina.com\/products\/sierra-18-0721-open-dry-joint-riser-gasket-replaces-mercruiser-27-864547a02-fits-4-3l-5-0l-5-7l-6-2l-dry-joint-manifold-and-riser","provider":"Good Vibes Marina","version":"1.0","type":"link"}