{"product_id":"4-exhaust-flapper-valve-fits-mercruiser-stern-drives-1994-up-replaces-12644a1-12644q01","title":"4\" Exhaust Flapper Valve – Fits MerCruiser Stern Drives 1994 \u0026 Up (Replaces 12644A1, 12644Q01)","description":"\u003csection\u003e\n\u003c!-- 🔧 Table Styles (include only once per page) --\u003e\n\u003cstyle\u003e\n  \/* Outer container allows horizontal scrolling (with iOS momentum) *\/\n  .ss-table-wrap { overflow-x:auto; -webkit-overflow-scrolling:touch; }\n\n  \/* Base table styles *\/\n  table.ss-table { width:100%; border-collapse:collapse; min-width:640px; }\n  table.ss-table th, table.ss-table td {\n    padding:10px 12px; border:1px solid #e5e7eb; text-align:left; vertical-align:top;\n  }\n\n  \/* Key: prevent wrapping, word breaks, and vertical text in headers *\/\n  table.ss-table th {\n    white-space:nowrap;       \/* Do not wrap *\/\n    word-break:normal;        \/* Don’t break words *\/\n    letter-spacing:normal;    \/* Prevent theme styles from stretching letters *\/\n    font-weight:600;\n    background:#f8fafc;\n  }\n\n  \/* Small screen optimization *\/\n  @media (max-width:480px){\n    table.ss-table th, table.ss-table td { padding:8px 10px; font-size:14px; }\n  }\n\u003c\/style\u003e\n\n\u003ch2\u003eProduct Details\u003c\/h2\u003e\n\u003cp\u003eThis \u003cstrong\u003e4\" Exhaust Flapper Valve – Fits MerCruiser Stern Drives 1994 \u0026amp; Up\u003c\/strong\u003e is designed to prevent water from entering the engine through the exhaust system. Engineered for MerCruiser stern drive models from 1994 and newer with 4-inch exhaust outlets, it is manufactured from a durable, compounded EPDM rubber with a UV stabilizer for weather resistance and long service life.\u003c\/p\u003e\n\u003cp\u003eIt serves as a direct replacement for MerCruiser parts 12644A1 and 12644Q01, as well as aftermarket equivalents from Sierra, Mallory, and GLM.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eInstalls externally on the exhaust outlet.\u003c\/li\u003e\n\u003cli\u003eMade from weather-resistant EPDM rubber with a UV stabilizer.\u003c\/li\u003e\n\u003cli\u003eKit includes two flapper valves and two stainless steel clamps.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003ePart Number Matrix\u003c\/h2\u003e\n\u003cp\u003eUse this matrix to confirm equivalent references across OEM and aftermarket.\u003c\/p\u003e\n\u003cdiv class=\"ss-table-wrap\"\u003e\n  \u003ctable class=\"ss-table\" aria-label=\"Part Number Matrix\"\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\u003eMerCruiser\u003c\/td\u003e\n        \u003ctd\u003e12644A1\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eMerCruiser\u003c\/td\u003e\n        \u003ctd\u003e12644Q01\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eMallory\u003c\/td\u003e\n        \u003ctd\u003e9-44001\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eGLM\u003c\/td\u003e\n        \u003ctd\u003e89250\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eSierra\u003c\/td\u003e\n        \u003ctd\u003e18-4457\u003c\/td\u003e\n      \u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\u003c\/div\u003e\n\n\u003ch2\u003eEngine \u0026amp; Model Compatibility\u003c\/h2\u003e\n\u003cp\u003eConfirm your engine model\/year in the table below.\u003c\/p\u003e\n\u003cp\u003eThis component is designed primarily for MerCruiser stern drives using a 4-inch exhaust system.\u003c\/p\u003e\n\u003cdiv class=\"ss-table-wrap\"\u003e\n  \u003ctable class=\"ss-table\" aria-label=\"Engine \u0026amp; Model Compatibility\"\u003e\n    \u003cthead\u003e\n      \u003ctr\u003e\n        \u003cth\u003eBrand\u003c\/th\u003e\n        \u003cth\u003eModel\u003c\/th\u003e\n        \u003cth\u003eRated HP\u003c\/th\u003e\n        \u003cth\u003eStroke\u003c\/th\u003e\n        \u003cth\u003eYears\u003c\/th\u003e\n        \u003cth\u003eOEM Part No.\u003c\/th\u003e\n        \u003cth\u003eNotes\u003c\/th\u003e\n      \u003c\/tr\u003e\n    \u003c\/thead\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eMerCruiser\u003c\/td\u003e\n        \u003ctd\u003eVarious Stern Drive Models\u003c\/td\u003e\n        \u003ctd\u003eVarious\u003c\/td\u003e\n        \u003ctd\u003e4-Stroke\u003c\/td\u003e\n        \u003ctd\u003e1994 \u0026amp; Up\u003c\/td\u003e\n        \u003ctd\u003e12644A1, 12644Q01\u003c\/td\u003e\n        \u003ctd\u003eFits 4\" exhaust systems\u003c\/td\u003e\n      \u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\u003c\/div\u003e\n\n\u003ch2\u003eTechnical Specs\u003c\/h2\u003e\n\u003cdl\u003e\n  \u003cdt\u003eProduct Type\u003c\/dt\u003e\n\u003cdd\u003eExhaust Flapper Valve\u003c\/dd\u003e\n  \u003cdt\u003eInstallation\u003c\/dt\u003e\n\u003cdd\u003eExternal, with clamp\u003c\/dd\u003e\n  \u003cdt\u003eSize\u003c\/dt\u003e\n\u003cdd\u003e4\" (101.6 mm)\u003c\/dd\u003e\n  \u003cdt\u003eMaterial\u003c\/dt\u003e\n\u003cdd\u003eEPDM Rubber with UV stabilizer\u003c\/dd\u003e\n  \u003cdt\u003eConnection\u003c\/dt\u003e\n\u003cdd\u003eStainless Steel Clamp (4-1\/16\" to 5\")\u003c\/dd\u003e\n  \u003cdt\u003eHousing Material\u003c\/dt\u003e\n\u003cdd\u003eRubber construction\u003c\/dd\u003e\n  \u003cdt\u003eHousing Color\u003c\/dt\u003e\n\u003cdd\u003eBlack\u003c\/dd\u003e\n  \u003cdt\u003eDimensions\u003c\/dt\u003e\n\u003cdd\u003e7.25 × 6.75 × 2 in (184.15 × 171.45 × 50.8 mm)\u003c\/dd\u003e\n  \u003cdt\u003eWeight\u003c\/dt\u003e\n\u003cdd\u003e0.5 lbs (0.227 kg)\u003c\/dd\u003e\n  \u003cdt\u003eWarranty\u003c\/dt\u003e\n\u003cdd\u003eLimited lifetime (Sierra brand)\u003c\/dd\u003e\n\u003c\/dl\u003e\n\n\u003ch2\u003eWhat’s in the Box\u003c\/h2\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cspan style=\"color:#d0021b;\"\u003e2 x\u003c\/span\u003e Exhaust Protector Valve (12644A1, 12644Q01)\u003c\/li\u003e\n  \u003cli\u003e\n\u003cspan style=\"color:#d0021b;\"\u003e2 x\u003c\/span\u003e Stainless Steel Clamp (4-1\/16\" to 5\")\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eInstallation Notes\u003c\/h2\u003e\n\u003col\u003e\n  \u003cli\u003eEnsure the engine is off, cool, and the vessel is stable.\u003c\/li\u003e\n  \u003cli\u003eLocate the exhaust outlets on the transom.\u003c\/li\u003e\n  \u003cli\u003eLoosen and remove the old clamp securing the existing flapper valve.\u003c\/li\u003e\n  \u003cli\u003eRemove the old flapper and clean the mounting surface on the exhaust pipe thoroughly.\u003c\/li\u003e\n  \u003cli\u003ePosition the new flapper valve over the exhaust outlet, ensuring it is correctly oriented to open outwards.\u003c\/li\u003e\n  \u003cli\u003eSlide the new stainless steel clamp over the flapper and position it in the designated groove.\u003c\/li\u003e\n  \u003cli\u003eTighten the clamp securely with a screwdriver or nut driver until snug. Do not overtighten.\u003c\/li\u003e\n  \u003cli\u003eRepeat the process for the second exhaust outlet if applicable.\u003c\/li\u003e\n\u003c\/ol\u003e\n\n\u003ch2\u003eTroubleshooting \u0026amp; FAQ\u003c\/h2\u003e\n\u003cdetails\u003e\n  \u003csummary\u003eHow do I know if this flapper valve will fit my specific MerCruiser engine?\u003c\/summary\u003e\n  \u003cp\u003eThis valve is designed for MerCruiser stern drive models from 1994 and newer that use a 4\" (101.6 mm) outside diameter exhaust system. The most reliable method is to match the OEM part number (12644A1 or 12644Q01) from your service manual or by inspecting the existing part.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n  \u003csummary\u003eWhat are the signs of a failing exhaust flapper?\u003c\/summary\u003e\n  \u003cp\u003eSigns of a bad or missing flapper include visible cracks, stiffness, or brittleness in the rubber; a rattling noise from the exhaust at idle; or, in severe cases, water ingestion leading to engine hydrolock. Regular inspection during seasonal maintenance is recommended.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n  \u003csummary\u003eHow often should I replace my exhaust flappers?\u003c\/summary\u003e\n  \u003cp\u003eIt is best practice to inspect them annually. Replacement frequency depends on usage and environmental factors (saltwater vs. freshwater). Replace them immediately if you see any signs of wear, cracking, or if the rubber has lost its flexibility.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n  \u003csummary\u003eCan I install these myself?\u003c\/summary\u003e\n  \u003cp\u003eYes, this is a common DIY task for boat owners with basic mechanical skills. The process involves removing the old clamp and flapper and securing the new one. However, if you are unsure, professional installation is always recommended to prevent improper installation that could lead to engine damage.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n  \u003csummary\u003eIs this a single flapper or a pair?\u003c\/summary\u003e\n  \u003cp\u003eThis product is sold as a kit that includes two flapper valves and two corresponding stainless steel clamps, suitable for a twin-exhaust setup.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n  \u003csummary\u003eOEM vs. Aftermarket?\u003c\/summary\u003e\n  \u003cp\u003eThis listing is an aftermarket replacement (not OEM). Built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility, batch-inspected for consistency.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n  \u003csummary\u003eShipping speed \u0026amp; cost?\u003c\/summary\u003e\n  \u003cp\u003eWe ship worldwide quickly—typical transit 5–15 days. Standard shipping is free; expedited options appear at checkout where available.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n  \u003csummary\u003eWarranty \u0026amp; returns?\u003c\/summary\u003e\n  \u003cp\u003eCovered by a 1-year warranty against manufacturing defects under normal use. If issues arise, contact support with your order details. Returns are accepted within our standard window (unused \u0026amp; in original condition). See our policy page or reach out for instructions.\u003c\/p\u003e\n\u003c\/details\u003e\n\n\u003ch2\u003eSafety \u0026amp; Important Info\u003c\/h2\u003e\n\u003cul\u003e\n  \u003cli\u003eVerify images\/specifications vs your original part. If anything differs—even if your model appears compatible—do not purchase.\u003c\/li\u003e\n  \u003cli\u003eThis is an aftermarket replacement, not an OEM component.\u003c\/li\u003e\n  \u003cli\u003eProfessional installation is recommended for safety and performance.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eAbout Sea Sierra\u003c\/h2\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003ePro-Grade Standards\u003c\/strong\u003e — We supply marine parts engineered to OEM-level tolerances and tested for real-world conditions.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eFast Global Fulfillment\u003c\/strong\u003e — Free standard delivery to most regions in 5–15 days.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eManufacturer-Direct Value\u003c\/strong\u003e — Fair pricing without compromising on materials or QC.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/section\u003e","brand":"SeaSierra","offers":[{"title":"Default Title","offer_id":50717898998075,"sku":"KF19B1002","price":24.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0826\/8673\/8747\/files\/KF19B1002.png?v=1762937807","url":"https:\/\/seasierra.com\/products\/4-exhaust-flapper-valve-fits-mercruiser-stern-drives-1994-up-replaces-12644a1-12644q01","provider":"SeaSierra","version":"1.0","type":"link"}