{"product_id":"lower-unit-gearcase-seal-kit-fits-johnson-evinrude-20-35-hp-replaces-396351-87680-18-2658","title":"Lower Unit Gearcase Seal Kit – Fits Johnson\/Evinrude 20-35 HP (Replaces 396351, 87680, 18-2658)","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; word-break:normal; letter-spacing:normal; font-weight:600; 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\u003csection\u003e\n\u003ch2\u003eProduct Details\u003c\/h2\u003e\n\u003cp\u003eThis aftermarket \u003cstrong\u003eLower Unit Gearcase Seal Kit\u003c\/strong\u003e is designed for a wide range of Johnson\/Evinrude 20, 25, 30, and 35 HP 2-stroke outboard engines manufactured between 1977 and 2005. It provides all the necessary seals and gaskets to service a leaking or damaged lower unit gearcase, restoring watertight integrity and preventing costly gear damage.\u003c\/p\u003e\n\u003cp\u003eThis kit serves as a direct replacement for Johnson\/Evinrude part number 396351 \/ 0396351, Sierra 18-2658, GLM 87680, and Mallory 9-74101, ensuring a precise fit and reliable performance.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eEngineered as a direct, model-specific replacement for easy installation.\u003c\/li\u003e\n\u003cli\u003eIncludes a complete set of seals, washers, and O-rings for a comprehensive overhaul.\u003c\/li\u003e\n\u003cli\u003eHelps prevent water intrusion and oil leaks, protecting internal gearcase components.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/section\u003e\n\u003csection\u003e\n\u003ch2\u003ePart Number Matrix\u003c\/h2\u003e\n\u003cp\u003eUse this matrix to confirm equivalent references across OEM and aftermarket suppliers.\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\u003eJohnson\/Evinrude\u003c\/td\u003e\n        \u003ctd\u003e396351 \/ 0396351\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eSierra\u003c\/td\u003e\n        \u003ctd\u003e18-2658\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eGLM\u003c\/td\u003e\n        \u003ctd\u003e87680\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eMallory\u003c\/td\u003e\n        \u003ctd\u003e9-74101\u003c\/td\u003e\n      \u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\u003c\/div\u003e\n\u003c\/section\u003e\n\u003csection\u003e\n\u003ch2\u003eEngine \u0026amp; Model Compatibility\u003c\/h2\u003e\n\u003cp\u003eConfirm your engine model and year in the table below to ensure correct fitment.\u003c\/p\u003e\n\u003cp\u003eThis kit is verified for the following Johnson\/Evinrude outboard models.\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\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\u003e20 HP\u003c\/td\u003e\n        \u003ctd\u003e20\u003c\/td\u003e\n        \u003ctd\u003e2-Stroke\u003c\/td\u003e\n        \u003ctd\u003e1985–1997\u003c\/td\u003e\n        \u003ctd\u003e396351\u003c\/td\u003e\n        \u003ctd\u003e\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003e25 HP\u003c\/td\u003e\n        \u003ctd\u003e25\u003c\/td\u003e\n        \u003ctd\u003e2-Stroke\u003c\/td\u003e\n        \u003ctd\u003e1985–2005\u003c\/td\u003e\n        \u003ctd\u003e396351\u003c\/td\u003e\n        \u003ctd\u003e\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003e30 HP\u003c\/td\u003e\n        \u003ctd\u003e30\u003c\/td\u003e\n        \u003ctd\u003e2-Stroke\u003c\/td\u003e\n        \u003ctd\u003e1985–1998, 2003\u003c\/td\u003e\n        \u003ctd\u003e396351\u003c\/td\u003e\n        \u003ctd\u003e\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003e33 HP\u003c\/td\u003e\n        \u003ctd\u003e33\u003c\/td\u003e\n        \u003ctd\u003e2-Stroke\u003c\/td\u003e\n        \u003ctd\u003e1997\u003c\/td\u003e\n        \u003ctd\u003e396351\u003c\/td\u003e\n        \u003ctd\u003e\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003e35 HP\u003c\/td\u003e\n        \u003ctd\u003e35\u003c\/td\u003e\n        \u003ctd\u003e2-Stroke\u003c\/td\u003e\n        \u003ctd\u003e1987–2001\u003c\/td\u003e\n        \u003ctd\u003e396351\u003c\/td\u003e\n        \u003ctd\u003e\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003e200 HP\u003c\/td\u003e\n        \u003ctd\u003e200\u003c\/td\u003e\n        \u003ctd\u003e2-Stroke\u003c\/td\u003e\n        \u003ctd\u003e1997\u003c\/td\u003e\n        \u003ctd\u003e396351\u003c\/td\u003e\n        \u003ctd\u003eSpecial application\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003e225 HP\u003c\/td\u003e\n        \u003ctd\u003e225\u003c\/td\u003e\n        \u003ctd\u003e2-Stroke\u003c\/td\u003e\n        \u003ctd\u003e2003\u003c\/td\u003e\n        \u003ctd\u003e396351\u003c\/td\u003e\n        \u003ctd\u003eSpecial application\u003c\/td\u003e\n      \u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\u003c\/div\u003e\n\u003c\/section\u003e\n\u003csection\u003e\n\u003ch2\u003eTechnical Specs\u003c\/h2\u003e\n\u003cdl\u003e\n  \u003cdt\u003eProduct Type\u003c\/dt\u003e\n\u003cdd\u003eLower Unit Gearcase Seal Kit\u003c\/dd\u003e\n  \u003cdt\u003eInstallation\u003c\/dt\u003e\n\u003cdd\u003eDirect replacement\u003c\/dd\u003e\n  \u003cdt\u003eWeight\u003c\/dt\u003e\n\u003cdd\u003eApprox. 2.39 oz (67.8 g)\u003c\/dd\u003e\n  \u003cdt\u003eWarranty\u003c\/dt\u003e\n\u003cdd\u003eManufacturer dependent, typically 1 year\u003c\/dd\u003e\n  \u003cdt\u003eOther Technical Attributes\u003c\/dt\u003e\n\u003cdd\u003eComplete kit includes all necessary seals for gearcase service\u003c\/dd\u003e\n\u003c\/dl\u003e\n\u003c\/section\u003e\n\u003csection\u003e\n\u003ch2\u003eWhat’s in the Box\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e1 x Impeller Plate Gasket\u003c\/li\u003e\n\u003cli\u003e1 x Shift Rod Washer\u003c\/li\u003e\n\u003cli\u003e2 x Oil Seals (Driveshaft)\u003c\/li\u003e\n\u003cli\u003e1 x Oil Seal\u003c\/li\u003e\n\u003cli\u003e1 x Oil Seal\u003c\/li\u003e\n\u003cli\u003e1 x Oil Seal\u003c\/li\u003e\n\u003cli\u003e1 x Oil Seal\u003c\/li\u003e\n\u003cli\u003e1 x Rubber Seal\u003c\/li\u003e\n\u003cli\u003e2 x Drain\/Fill Plug Washers\u003c\/li\u003e\n\u003cli\u003e1 x O-Ring\u003c\/li\u003e\n\u003cli\u003e2 x O-Ring\u003c\/li\u003e\n\u003cli\u003e1 x O-Ring\u003c\/li\u003e\n\u003cli\u003e3 x O-Ring\u003c\/li\u003e\n\u003cli\u003e2 x O-Ring\u003c\/li\u003e\n\u003cli\u003e1 x O-Ring\u003c\/li\u003e\n\u003cli\u003e1 x O-Ring\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/section\u003e\n\u003csection\u003e\n\u003ch2\u003eInstallation Notes\u003c\/h2\u003e\n\u003col\u003e\n\u003cli\u003ePosition the engine securely and place a drain pan under the lower unit.\u003c\/li\u003e\n\u003cli\u003eRemove the lower drain\/fill screw and the upper vent screw to drain the gearcase oil completely.\u003c\/li\u003e\n\u003cli\u003eDisconnect the shift linkage and remove the bolts securing the lower unit to the midsection.\u003c\/li\u003e\n\u003cli\u003eCarefully lower and remove the gearcase assembly from the engine.\u003c\/li\u003e\n\u003cli\u003eDisassemble the gearcase to access the propeller shaft, driveshaft, and shift rod seals. A service manual for your specific model is highly recommended.\u003c\/li\u003e\n\u003cli\u003eCarefully remove all old seals, O-rings, and gaskets, taking care not to scratch the housing surfaces.\u003c\/li\u003e\n\u003cli\u003eClean all sealing surfaces thoroughly to remove any old sealant or corrosion.\u003c\/li\u003e\n\u003cli\u003eInstall the new seals and O-rings from the kit, lightly lubricating them with marine grease or clean gear oil.\u003c\/li\u003e\n\u003cli\u003eReassemble the gearcase, ensuring all components are torqued to manufacturer specifications.\u003c\/li\u003e\n\u003cli\u003eReinstall the lower unit, connect the shift linkage, and refill the gearcase with the correct type and amount of marine gear lubricant.\u003c\/li\u003e\n\u003cli\u003eInstall new washers on the drain and vent plugs, and tighten them securely.\u003c\/li\u003e\n\u003c\/ol\u003e\n\u003c\/section\u003e\n\u003csection\u003e\n\u003ch2\u003eTroubleshooting \u0026amp; FAQ\u003c\/h2\u003e\n\u003cdetails\u003e\u003csummary\u003eHow do I know if my gearcase seals are failing?\u003c\/summary\u003e\u003cp\u003eCommon signs include milky, cream-colored gear oil (indicating water intrusion) or a visible oil leak around the propeller shaft or drain plugs. You may also find fishing line tangled behind the propeller, which can quickly damage the prop shaft seal.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eWhy are there \"special application\" notes for the 200\/225 HP models?\u003c\/summary\u003e\u003cp\u003eWhile this kit's part number is referenced for some larger V6 models in specific years, it's primarily intended for the 20-35 HP range. The V6 application may only use a portion of the kit or relate to a sub-assembly. Please verify the exact parts required for your V6 engine before ordering.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eWhy might there be extra O-rings or seals in my kit?\u003c\/summary\u003e\u003cp\u003eAftermarket kits are often designed to cover multiple model years or variations that use slightly different components. It is normal to have a few unused parts after a correct installation on your specific engine.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eCan I replace just one leaking seal?\u003c\/summary\u003e\u003cp\u003eWhile possible, it is best practice to replace all the seals in the gearcase at the same time. If one seal has failed due to age or wear, others are likely to fail soon after. This comprehensive approach prevents repeated disassembly and potential damage.\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\u003c\/section\u003e\n\u003csection\u003e\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\u003c\/section\u003e\n\u003csection\u003e\n\u003ch2\u003eAbout Sea Sierra\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cb\u003ePro-Grade Standards\u003c\/b\u003e — We supply marine parts engineered to OEM-level tolerances and tested for real-world conditions.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eFast Global Fulfillment\u003c\/b\u003e — Free standard delivery to most regions in 5–15 days.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eManufacturer-Direct Value\u003c\/b\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":50723792191803,"sku":"SS-24OSK702","price":31.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0826\/8673\/8747\/files\/SS-24OSK702.png?v=1763031908","url":"https:\/\/seasierra.com\/products\/lower-unit-gearcase-seal-kit-fits-johnson-evinrude-20-35-hp-replaces-396351-87680-18-2658","provider":"SeaSierra","version":"1.0","type":"link"}