{"product_id":"lower-unit-seal-kit-fits-johnson-evinrude-25-50-hp-2-stroke-replaces-433550-18-2694","title":"Lower Unit Seal Kit – Fits Johnson\/Evinrude 25-50 HP 2-Stroke (Replaces 433550, 18-2694)","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 complete \u003cstrong\u003eLower Unit Seal Kit – Fits Johnson\/Evinrude 25-50 HP 2-Stroke (Replaces 433550, 18-2694)\u003c\/strong\u003e contains all necessary seals, gaskets, and O-rings to rebuild the gearcase on compatible Johnson\/Evinrude outboard engines. It is designed for 2-stroke models including 25 HP (1990–1995, D suffix only), 40 HP (1989 \u0026amp; Up), 48 HP (1989–1996), and 50 HP (1989 \u0026amp; Up).\u003c\/p\u003e\n\u003cp\u003eThis kit provides a direct replacement for Johnson\/Evinrude OEM parts 433550, 0433550, and 777551, as well as aftermarket equivalents Sierra 18-2694, GLM 87614, and Mallory 9-74104.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eDesigned for direct OEM-replacement installation.\u003c\/li\u003e\n  \u003cli\u003eComprehensive kit for a full gearcase reseal.\u003c\/li\u003e\n  \u003cli\u003eConstructed from durable rubber, metal, and synthetic materials to withstand the marine environment.\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\u003eJohnson\/Evinrude\u003c\/td\u003e\n        \u003ctd\u003e433550 \/ 0433550 \/ 777551\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eSierra\u003c\/td\u003e\n        \u003ctd\u003e18-2694\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eGLM\u003c\/td\u003e\n        \u003ctd\u003e87614\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eMallory\u003c\/td\u003e\n        \u003ctd\u003e9-74104\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\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\u003eJohnson\/Evinrude\u003c\/td\u003e\n        \u003ctd\u003eOutboard\u003c\/td\u003e\n        \u003ctd\u003e25\u003c\/td\u003e\n        \u003ctd\u003e2-Stroke\u003c\/td\u003e\n        \u003ctd\u003e1990–1995\u003c\/td\u003e\n        \u003ctd\u003e433550\u003c\/td\u003e\n        \u003ctd\u003eD suffix only\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eJohnson\/Evinrude\u003c\/td\u003e\n        \u003ctd\u003eOutboard\u003c\/td\u003e\n        \u003ctd\u003e40\u003c\/td\u003e\n        \u003ctd\u003e2-Stroke\u003c\/td\u003e\n        \u003ctd\u003e1989 \u0026amp; Up\u003c\/td\u003e\n        \u003ctd\u003e433550\u003c\/td\u003e\n        \u003ctd\u003e\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eJohnson\/Evinrude\u003c\/td\u003e\n        \u003ctd\u003eOutboard\u003c\/td\u003e\n        \u003ctd\u003e48\u003c\/td\u003e\n        \u003ctd\u003e2-Stroke\u003c\/td\u003e\n        \u003ctd\u003e1989–1996\u003c\/td\u003e\n        \u003ctd\u003e433550\u003c\/td\u003e\n        \u003ctd\u003e\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eJohnson\/Evinrude\u003c\/td\u003e\n        \u003ctd\u003eOutboard\u003c\/td\u003e\n        \u003ctd\u003e50\u003c\/td\u003e\n        \u003ctd\u003e2-Stroke\u003c\/td\u003e\n        \u003ctd\u003e1989 \u0026amp; Up\u003c\/td\u003e\n        \u003ctd\u003e433550\u003c\/td\u003e\n        \u003ctd\u003e\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\u003eGearcase\/Lower Unit Seal Kit\u003c\/dd\u003e\n  \u003cdt\u003eInstallation\u003c\/dt\u003e\n\u003cdd\u003eOEM Replacement\u003c\/dd\u003e\n  \u003cdt\u003eConnection\u003c\/dt\u003e\n\u003cdd\u003eLower Unit\/Gearcase\u003c\/dd\u003e\n  \u003cdt\u003eHousing Material\u003c\/dt\u003e\n\u003cdd\u003eVarious (Rubber, Metal, Synthetic)\u003c\/dd\u003e\n  \u003cdt\u003eWarranty\u003c\/dt\u003e\n\u003cdd\u003eVaries by manufacturer: 1 Year (Aftermarket)\u003c\/dd\u003e\n  \u003cdt\u003eOther Technical Attributes\u003c\/dt\u003e\n\u003cdd\u003eComplete seal kit for rebuilding lower unit\u003c\/dd\u003e\n\u003c\/dl\u003e\n\n\u003ch2\u003eWhat’s in the Box\u003c\/h2\u003e\n\u003cul\u003e\n  \u003cli\u003e1 x O-Ring (305270)\u003c\/li\u003e\n  \u003cli\u003e1 x O-Ring (338522)\u003c\/li\u003e\n  \u003cli\u003e1 x Wear plate gasket (336530)\u003c\/li\u003e\n  \u003cli\u003e1 x O-Ring (310327\/910582)\u003c\/li\u003e\n  \u003cli\u003e1 x O-Ring (317178)\u003c\/li\u003e\n  \u003cli\u003e1 x O-Ring (553126)\u003c\/li\u003e\n  \u003cli\u003e1 x O-Ring (318372)\u003c\/li\u003e\n  \u003cli\u003e1 x Seal (333758)\u003c\/li\u003e\n  \u003cli\u003e1 x Oil seal (321466)\u003c\/li\u003e\n  \u003cli\u003e1 x Oil seal (332205)\u003c\/li\u003e\n  \u003cli\u003e1 x Oil seal (342786)\u003c\/li\u003e\n  \u003cli\u003e1 x Oil seal (342887)\u003c\/li\u003e\n  \u003cli\u003e1 x Seal (315748\/341732)\u003c\/li\u003e\n  \u003cli\u003e1 x Gasket (311598)\u003c\/li\u003e\n  \u003cli\u003e1 x Drain plug Screw (318544)\u003c\/li\u003e\n  \u003cli\u003e1 x Housing Seal ring (324981)\u003c\/li\u003e\n  \u003cli\u003e1 x Drain plug (309243)\u003c\/li\u003e\n  \u003cli\u003e1 x O-Ring (336982)\u003c\/li\u003e\n  \u003cli\u003e1 x Retaining screw (324852)\u003c\/li\u003e\n  \u003cli\u003e1 x Washer seal ring (332584)\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eInstallation Notes\u003c\/h2\u003e\n\u003col\u003e\n  \u003cli\u003ePlace a drain pan under the lower unit and remove the upper and lower gear oil drain screws to empty the old oil.\u003c\/li\u003e\n  \u003cli\u003eDisconnect the shift linkage and remove the bolts securing the lower unit to the midsection. Carefully lower the unit.\u003c\/li\u003e\n  \u003cli\u003eDisassemble the gearcase housing, propeller shaft assembly, and driveshaft components, noting the order of removal.\u003c\/li\u003e\n  \u003cli\u003eCarefully remove all old seals, o-rings, and gaskets from the housing, bearing carriers, and shafts.\u003c\/li\u003e\n  \u003cli\u003eClean all sealing surfaces thoroughly, ensuring they are free of old adhesive, corrosion, or debris.\u003c\/li\u003e\n  \u003cli\u003eInstall the new seals, gaskets, and o-rings from the kit, using appropriate sealants where specified by the service manual.\u003c\/li\u003e\n  \u003cli\u003eReassemble the lower unit components in reverse order of disassembly, torquing fasteners to manufacturer specifications.\u003c\/li\u003e\n  \u003cli\u003eReinstall the lower unit onto the engine and reconnect the shift linkage.\u003c\/li\u003e\n  \u003cli\u003eFill the gearcase with new, recommended marine gear lubricant from the bottom drain hole until it seeps from the top hole. Re-install both drain screws with new gaskets.\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 lower unit seals are failing?\u003c\/summary\u003e\u003cp\u003eCommon signs include milky or water-contaminated gear lube (indicating water intrusion), visible oil leaks around the propeller shaft or driveshaft, or a metallic sheen in the drained oil, which can point to internal wear caused by water damage.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eIs this kit compatible with a 25 HP engine from 1989?\u003c\/summary\u003e\u003cp\u003eNo. This kit is specifically listed for 25 HP models manufactured from 1990–1995 that have a \"D\" suffix. It is not compatible with earlier models. Please verify your engine details before ordering.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eWhat is the recommended replacement interval for gearcase seals?\u003c\/summary\u003e\u003cp\u003eAs a best practice, lower unit seals should be inspected during every annual service. We recommend a full replacement every 3-5 years or anytime the lower unit is serviced for other work, like a water pump replacement, to ensure long-term reliability.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eDo I need special tools for installation?\u003c\/summary\u003e\u003cp\u003eWhile standard hand tools can complete most of the job, specialized tools like a bearing carrier puller, a propeller shaft puller, and seal installation drivers are highly recommended. Using the correct tools prevents damage to the components and ensures the new seals are seated correctly.\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 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\n\u003c\/section\u003e","brand":"SeaSierra","offers":[{"title":"Default Title","offer_id":50723801432379,"sku":"OSK602","price":29.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0826\/8673\/8747\/files\/OSK602.png?v=1763032191","url":"https:\/\/seasierra.com\/products\/lower-unit-seal-kit-fits-johnson-evinrude-25-50-hp-2-stroke-replaces-433550-18-2694","provider":"SeaSierra","version":"1.0","type":"link"}