{"product_id":"89260-exhaust-flapper-clamp-for-5-6-outlets","title":"89260 Exhaust Flapper \u0026 Clamp for 5\" \u0026 6\" Outlets | JLM Marine","description":"\u003ch2\u003eExhaust Flapper \u0026amp; Clamp for 5\" \u0026amp; 6\" Outlets – Universal Marine Backflow Preventer\u003c\/h2\u003e\n\n\u003cp\u003eThis exhaust flapper and clamp assembly is designed to fit marine engines with \u003cstrong\u003e5\" or 6\" exhaust outlets\u003c\/strong\u003e. It functions as a backflow preventer, stopping water from entering your engine through the exhaust system when the boat is at rest or during wave action. The adjustable stainless steel clamp allows for installation on both outlet sizes—simply trim the band to fit 5\" applications.\u003c\/p\u003e\n\n\u003cp\u003eThis aftermarket replacement directly crosses to \u003cstrong\u003eSierra 18-4458\u003c\/strong\u003e, \u003cstrong\u003eOEM 89260\u003c\/strong\u003e, and multiple other part numbers listed below. It provides reliable protection against exhaust backflow at a competitive price point.\u003c\/p\u003e\n\n\u003cul\u003e\n  \u003cli\u003eFits \u003cstrong\u003e6\" outlets without modification\u003c\/strong\u003e; trim clamp band for 5\" outlets\u003c\/li\u003e\n  \u003cli\u003eIncludes flapper valve and stainless steel adjustable clamp\u003c\/li\u003e\n  \u003cli\u003ePrevents water intrusion through exhaust during idle or reverse flow conditions\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003ePart Number Cross-Reference\u003c\/h2\u003e\n\n\u003cp\u003eUse this table to confirm equivalent part numbers across OEM and aftermarket brands.\u003c\/p\u003e\n\n\u003cdiv style=\"overflow-x:auto;\"\u003e\n  \u003ctable border=\"1\" cellpadding=\"8\" cellspacing=\"0\" style=\"width:100%; border-collapse:collapse;\"\u003e\n    \u003cthead\u003e\n      \u003ctr\u003e\n        \u003cth\u003eBrand\u003c\/th\u003e\n        \u003cth\u003ePart Number\u003c\/th\u003e\n      \u003c\/tr\u003e\n    \u003c\/thead\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eOEM\u003c\/td\u003e\n        \u003ctd\u003e89260\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eSierra\u003c\/td\u003e\n        \u003ctd\u003e18-4458, SR18.4458\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eAftermarket\u003c\/td\u003e\n        \u003ctd\u003e107751, 4458, 47-4458, 58560, DN-184458, 4JQTXDCTNHNUGDK2\u003c\/td\u003e\n      \u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\u003c\/div\u003e\n\n\u003ch2\u003eCompatible Engine Models\u003c\/h2\u003e\n\n\u003cp\u003eThis exhaust flapper is a \u003cstrong\u003euniversal fit\u003c\/strong\u003e for marine engines equipped with 5\" or 6\" exhaust outlets. Verify your outlet diameter before ordering.\u003c\/p\u003e\n\n\u003ch2\u003eTechnical Specifications\u003c\/h2\u003e\n\n\u003ctable border=\"1\" cellpadding=\"8\" cellspacing=\"0\" style=\"width:100%; border-collapse:collapse;\"\u003e\n  \u003cthead\u003e\n    \u003ctr\u003e\n      \u003cth\u003eSpecification\u003c\/th\u003e\n      \u003cth\u003eValue\u003c\/th\u003e\n    \u003c\/tr\u003e\n  \u003c\/thead\u003e\n  \u003ctbody\u003e\n    \u003ctr\u003e\n      \u003ctd\u003eOutlet Diameter\u003c\/td\u003e\n      \u003ctd\u003e5\" \/ 6\" (adjustable)\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd\u003eFunction\u003c\/td\u003e\n      \u003ctd\u003eExhaust backflow preventer\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd\u003eClamp Material\u003c\/td\u003e\n      \u003ctd\u003eStainless steel\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd\u003eModification Required\u003c\/td\u003e\n      \u003ctd\u003eNone for 6\"; trim band for 5\"\u003c\/td\u003e\n    \u003c\/tr\u003e\n  \u003c\/tbody\u003e\n\u003c\/table\u003e\n\n\u003ch2\u003ePackage Contents\u003c\/h2\u003e\n\n\u003cul\u003e\n  \u003cli\u003e1 × Exhaust flapper valve\u003c\/li\u003e\n  \u003cli\u003e1 × Stainless steel adjustable clamp\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eInstallation Guide\u003c\/h2\u003e\n\n\u003col\u003e\n  \u003cli\u003eMeasure your exhaust outlet diameter to confirm it is 5\" or 6\". For 5\" outlets, you will need to trim the clamp band.\u003c\/li\u003e\n  \u003cli\u003eIf installing on a 5\" outlet, use tin snips or metal shears to carefully cut the stainless steel band to the proper length for a 5\" diameter circle.\u003c\/li\u003e\n  \u003cli\u003eSlide the clamp over the exhaust outlet with the flapper valve positioned to open outward (away from the engine).\u003c\/li\u003e\n  \u003cli\u003ePosition the flapper so it hangs vertically when the boat is level. Ensure the hinge is at the top.\u003c\/li\u003e\n  \u003cli\u003eTighten the clamp securely using a screwdriver or nut driver, ensuring even pressure around the circumference.\u003c\/li\u003e\n  \u003cli\u003eCheck that the flapper moves freely and is not binding on the outlet or clamp hardware.\u003c\/li\u003e\n  \u003cli\u003eStart the engine and verify exhaust gases push the flapper open during operation.\u003c\/li\u003e\n  \u003cli\u003eShut down the engine and confirm the flapper closes fully to prevent backflow.\u003c\/li\u003e\n  \u003cli\u003eInspect the clamp periodically for corrosion or loosening, and replace the flapper if cracking or stiffness develops.\u003c\/li\u003e\n\u003c\/ol\u003e\n\n\u003ch2\u003eTroubleshooting \u0026amp; FAQ\u003c\/h2\u003e\n\n\u003cp\u003e\u003cstrong\u003eQ: How do I know if I need a 5\" or 6\" flapper?\u003c\/strong\u003e\u003cbr\u003e\nA: Measure the outer diameter of your exhaust outlet pipe. This flapper fits both sizes—use it as-is for 6\" or trim the clamp band for 5\".\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eQ: How do I trim the clamp for a 5\" outlet?\u003c\/strong\u003e\u003cbr\u003e\nA: Use tin snips or aviation shears to cut the stainless steel band to match a 5\" diameter. Test-fit before final tightening to ensure proper overlap and tension.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eQ: How often should I replace the exhaust flapper?\u003c\/strong\u003e\u003cbr\u003e\nA: Inspect annually or whenever you notice reduced engine performance, water intrusion, or visible cracking in the rubber. Replace every 2–3 years in harsh saltwater environments.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eQ: The flapper won't close fully—what's wrong?\u003c\/strong\u003e\u003cbr\u003e\nA: Check for debris or salt buildup on the hinge and flapper surface. Ensure the clamp is not over-tightened, which can distort the outlet and prevent proper sealing.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eQ: Will this fit my sterndrive or inboard engine?\u003c\/strong\u003e\u003cbr\u003e\nA: Yes, as long as your exhaust outlet is 5\" or 6\" in diameter. Measure carefully to confirm fitment.\u003c\/p\u003e\n\n\u003ch2\u003eImportant Notes\u003c\/h2\u003e\n\n\u003cul\u003e\n  \u003cli\u003eVerify that the product images and specifications match your original part. If discrepancies exist—even if your model is listed—do not proceed with the purchase.\u003c\/li\u003e\n  \u003cli\u003eThis product is an aftermarket replacement part and is not an OEM component.\u003c\/li\u003e\n  \u003cli\u003eProfessional installation is recommended to ensure safety and optimal performance.\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"JLM Marine","offers":[{"title":"Default Title","offer_id":51015587529017,"sku":"23EF445","price":39.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0885\/0433\/6697\/files\/23EF445_30b291ea-8ab0-4fbe-8db7-e025a0067815.jpg?v=1754990453","url":"https:\/\/jlmmarine.com\/ru\/products\/89260-exhaust-flapper-clamp-for-5-6-outlets","provider":"JLM Marine Boat Parts Limited","version":"1.0","type":"link"}