{"product_id":"oil-seal-fits-mercury-mariner-8hp-9-9hp-15hp-4-stroke-replaces-26-413651-18-0581","title":"Oil Seal – Fits Mercury Mariner 8HP 9.9HP 15HP 4-Stroke (Replaces 26-413651, 18-0581)","description":"\u003cstyle\u003e\n  .ss-table-wrap { overflow-x:auto; -webkit-overflow-scrolling:touch; }\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  table.ss-table th {\n    white-space:nowrap;\n    word-break:normal;\n    letter-spacing:normal;\n    font-weight:600;\n    background:#f8fafc;\n  }\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\u003eOil Seal – Fits Mercury Mariner 8HP 9.9HP 15HP 4-Stroke\u003c\/strong\u003e is designed for Mercury Mariner Quicksilver Marine 8hp, 9.9hp, and 15hp (323 cc) 4-Stroke outboard motors. Engineered as a direct-fit replacement for the lower gearcase unit, it ensures reliable sealing and protection for your outboard's critical components.\u003c\/p\u003e\n\u003cp\u003eThis seal replaces Mercury Marine OEM part numbers 26-413651 and 18-0581, providing a cost-effective aftermarket solution.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003ePrecision-fit for Mercury Mariner 8\/9.9\/15 HP 4-Stroke (323 cc) engines\u003c\/li\u003e\n  \u003cli\u003eSuitable for lower gearcase applications\u003c\/li\u003e\n  \u003cli\u003eDirect interchange for 26-413651 and 18-0581\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\u003eMercury Marine\u003c\/td\u003e\n        \u003ctd\u003e26-413651\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eMercury Marine\u003c\/td\u003e\n        \u003ctd\u003e18-0581\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\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\u003eOEM Part No.\u003c\/th\u003e\n      \u003c\/tr\u003e\n    \u003c\/thead\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eMercury Mariner Quicksilver Marine\u003c\/td\u003e\n        \u003ctd\u003e8\/9.9\/15 HP (323 cc)\u003c\/td\u003e\n        \u003ctd\u003e8, 9.9, 15\u003c\/td\u003e\n        \u003ctd\u003e4-Stroke\u003c\/td\u003e\n        \u003ctd\u003e26-413651, 18-0581\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\u003ePart Type\u003c\/dt\u003e\n  \u003cdd\u003eOil Seal\u003c\/dd\u003e\n  \u003cdt\u003eApplication\u003c\/dt\u003e\n  \u003cdd\u003eLower Gearcase Unit\u003c\/dd\u003e\n  \u003cdt\u003eCompatible Engine Displacement\u003c\/dt\u003e\n  \u003cdd\u003e323 cc\u003c\/dd\u003e\n  \u003cdt\u003eStroke Type\u003c\/dt\u003e\n  \u003cdd\u003e4-Stroke\u003c\/dd\u003e\n  \u003cdt\u003eCompatible HP Range\u003c\/dt\u003e\n  \u003cdd\u003e8, 9.9, 15 HP\u003c\/dd\u003e\n\u003c\/dl\u003e\n\n\u003ch2\u003eWhat's in the Box\u003c\/h2\u003e\n\u003cul\u003e\n  \u003cli\u003e\u003cstrong\u003e1 × Oil Seal\u003c\/strong\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eInstallation Notes\u003c\/h2\u003e\n\u003col\u003e\n  \u003cli\u003eDisconnect the fuel line and ensure the engine is completely off before beginning work.\u003c\/li\u003e\n  \u003cli\u003eRemove the lower gearcase unit from the outboard motor following the manufacturer's service manual.\u003c\/li\u003e\n  \u003cli\u003eCarefully extract the old oil seal using an appropriate seal puller or pick tool, avoiding damage to the housing.\u003c\/li\u003e\n  \u003cli\u003eClean the seal bore thoroughly to remove any debris, corrosion, or old sealant residue.\u003c\/li\u003e\n  \u003cli\u003eLightly lubricate the new seal lip with marine-grade grease or gearcase oil.\u003c\/li\u003e\n  \u003cli\u003eInstall the new seal squarely into the bore using a seal driver or appropriately sized socket.\u003c\/li\u003e\n  \u003cli\u003eTap evenly around the seal perimeter until it seats fully and flush with the housing surface.\u003c\/li\u003e\n  \u003cli\u003eReassemble the lower gearcase unit, refill with the correct gear oil, and check for leaks after initial operation.\u003c\/li\u003e\n\u003c\/ol\u003e\n\n\u003ch2\u003eTroubleshooting \u0026amp; FAQ\u003c\/h2\u003e\n\u003cdetails\u003e\u003csummary\u003eHow do I know if my oil seal needs replacement?\u003c\/summary\u003e\u003cp\u003eSigns include visible oil leaks around the lower gearcase, low gear oil levels, or milky\/contaminated oil indicating water intrusion. Replace the seal if you notice any of these symptoms.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eIs this seal compatible with all 8–15 HP Mercury engines?\u003c\/summary\u003e\u003cp\u003eNo. This seal is designed exclusively for Mercury Mariner 8hp, 9.9hp, and 15hp 4-Stroke (323 cc) models. Always verify your engine's part number against 26-413651 or 18-0581 before purchase.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eCan I reuse the old seal during reassembly?\u003c\/summary\u003e\u003cp\u003eNo. Oil seals are single-use components. Reusing a seal can lead to improper seating, leaks, and potential damage to the gearcase.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eDo I need any special tools to install this seal?\u003c\/summary\u003e\u003cp\u003eA seal driver or appropriately sized socket is recommended to ensure even installation. A seal puller or pick tool is helpful for removing the old seal without damaging the housing.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eWhat type of lubricant should I use on the seal?\u003c\/summary\u003e\u003cp\u003eUse marine-grade grease or the same gear oil specified for your lower unit. Avoid petroleum-based lubricants that may degrade the seal material.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eHow often should this seal be replaced?\u003c\/summary\u003e\u003cp\u003eReplace the seal whenever you service the lower gearcase, notice leaks, or during routine maintenance intervals recommended in your engine's service manual—typically every 2–3 years or 100 hours of operation.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eOEM vs. Aftermarket?\u003c\/summary\u003e\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\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eShipping speed \u0026amp; cost\u003c\/summary\u003e\u003cp\u003eWe ship worldwide quickly—typical transit 5–15 days. Standard shipping is free; expedited options appear at checkout where available.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eWarranty \u0026amp; returns\u003c\/summary\u003e\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\u003c\/details\u003e\n\n\u003ch2\u003eSafety \u0026amp; Important Info\u003c\/h2\u003e\n\u003cul\u003e\n  \u003cli\u003eVerify images\/specifications against 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\u003ePro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and tested for real-world conditions.\u003c\/li\u003e\n  \u003cli\u003eFast Global Fulfillment — Free standard delivery to most regions in 5–15 days.\u003c\/li\u003e\n  \u003cli\u003eManufacturer-Direct Value — Fair pricing without compromising on materials or QC.\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"SeaSierra","offers":[{"title":"Default Title","offer_id":51025915314491,"sku":"3486","price":18.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0826\/8673\/8747\/files\/3499599_1730687101489.webp?v=1772975125","url":"https:\/\/seasierra.com\/products\/oil-seal-fits-mercury-mariner-8hp-9-9hp-15hp-4-stroke-replaces-26-413651-18-0581","provider":"SeaSierra","version":"1.0","type":"link"}