{"product_id":"gearcase-oil-seal-fits-omc-replaces-18-2028-318973-321480","title":"Gearcase Oil Seal – Fits OMC (Replaces 18-2028, 318973, 321480)","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\u003eGearcase Oil Seal – Fits OMC (Replaces 18-2028, 318973, 321480)\u003c\/strong\u003e is designed as a direct-fit replacement for OMC marine engines requiring a reliable gearcase seal. Engineered to prevent fluid leaks and protect lower unit integrity, this seal ensures consistent performance across a range of OMC applications.\u003c\/p\u003e\n\u003cp\u003eThis aftermarket component directly replaces Sierra 18-2028, GLM 86170, OMC 318973, OMC 321480, OMC 0777541, and Mallory 9-76207.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eSingle oil seal for gearcase applications\u003c\/li\u003e\n  \u003cli\u003eBuilt to OEM specifications for reliable sealing\u003c\/li\u003e\n  \u003cli\u003eCompatible with OMC marine engine lower units\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\u003eSierra\u003c\/td\u003e\n        \u003ctd\u003e18-2028\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eGLM\u003c\/td\u003e\n        \u003ctd\u003e86170\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eOMC\u003c\/td\u003e\n        \u003ctd\u003e321480\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eOMC\u003c\/td\u003e\n        \u003ctd\u003e0318973\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eOMC\u003c\/td\u003e\n        \u003ctd\u003e0777541\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eMallory\u003c\/td\u003e\n        \u003ctd\u003e9-76207\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\u003eApplication\u003c\/th\u003e\n      \u003c\/tr\u003e\n    \u003c\/thead\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eOMC\u003c\/td\u003e\n        \u003ctd\u003eGearcase Oil Seal For OMC Marine Engine\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\u003eGearcase Oil Seal\u003c\/dd\u003e\n  \u003cdt\u003eOEM Numbers\u003c\/dt\u003e\n  \u003cdd\u003e2895, 321480, 318973\u003c\/dd\u003e\n  \u003cdt\u003eApplication\u003c\/dt\u003e\n  \u003cdd\u003eOMC Marine Engine Lower Unit\u003c\/dd\u003e\n  \u003cdt\u003eQuantity\u003c\/dt\u003e\n  \u003cdd\u003e1 piece\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\u003eDrain gearcase oil completely and clean the seal housing area of any old sealant or debris.\u003c\/li\u003e\n  \u003cli\u003eInspect the shaft for scoring or roughness that could damage the new seal.\u003c\/li\u003e\n  \u003cli\u003eLightly lubricate the seal lip with gearcase oil before installation.\u003c\/li\u003e\n  \u003cli\u003ePress the seal squarely into the housing using an appropriately sized seal driver to avoid cocking.\u003c\/li\u003e\n  \u003cli\u003eEnsure the seal is fully seated to the correct depth per manufacturer specifications.\u003c\/li\u003e\n  \u003cli\u003eRefill gearcase with the recommended oil type and quantity.\u003c\/li\u003e\n  \u003cli\u003eCheck for leaks after initial operation and re-torque fasteners as needed.\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 my gearcase seal needs replacement?\u003c\/summary\u003e\n  \u003cp\u003eCommon signs include visible oil leaks around the lower unit, milky gearcase oil indicating water intrusion, or low oil levels between service intervals. Inspect seals during routine maintenance or whenever the lower unit is serviced.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n  \u003csummary\u003eCan I reuse an old seal during reassembly?\u003c\/summary\u003e\n  \u003cp\u003eNo. Once removed, oil seals lose their sealing integrity and should always be replaced with new ones to prevent leaks and contamination.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n  \u003csummary\u003eWhat causes premature seal failure?\u003c\/summary\u003e\n  \u003cp\u003eShaft damage, improper installation, contaminated oil, or running the lower unit dry can all cause seals to fail early. Always inspect mating surfaces and use clean, recommended lubricants.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n  \u003csummary\u003eWill this seal fit all OMC models?\u003c\/summary\u003e\n  \u003cp\u003eThis seal fits OMC marine engines that originally used part numbers 318973, 321480, or 0777541. Always cross-reference your engine's service manual or original seal dimensions to confirm fit.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n  \u003csummary\u003eDo I need special tools to install this seal?\u003c\/summary\u003e\n  \u003cp\u003eA seal driver or appropriately sized socket that matches the outer diameter of the seal is recommended to ensure even, square installation without damaging the seal or housing.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n  \u003csummary\u003eWhat type of oil should I use after installation?\u003c\/summary\u003e\n  \u003cp\u003eUse the gearcase oil type and viscosity specified in your engine's service manual. Using incorrect oil can affect seal performance and lower unit longevity.\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 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":51025914888507,"sku":"2895","price":21.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0826\/8673\/8747\/files\/3483605_1730083083074.webp?v=1772975106","url":"https:\/\/seasierra.com\/products\/gearcase-oil-seal-fits-omc-replaces-18-2028-318973-321480","provider":"SeaSierra","version":"1.0","type":"link"}