{"product_id":"lower-unit-seal-kit-fits-honda-bf75-bf90-outboard-motors-replaces-18-8366-91251-zw1-003-91252-zw1-003-91253-zw1-003-91254-zw1-003-91255-zw1-003","title":"Lower Unit Seal Kit – Fits Honda BF75\/BF90 Outboard Motors (Replaces 18-8366, 91251-ZW1-003, 91252-ZW1-003, 91253-ZW1-003, 91254-ZW1-003, 91255-ZW1-003)","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 comprehensive \u003cstrong\u003eLower Unit Seal Kit – Fits Honda BF75\/BF90 Outboard Motors\u003c\/strong\u003e is designed to restore the gearcase integrity of Honda 75-90 HP, 4-Stroke outboards from 1997-1998 and later models. It provides all the essential seals to prevent water intrusion and oil leaks, ensuring your lower unit runs smoothly and efficiently.\u003c\/p\u003e\n\u003cp\u003eThe kit serves as a direct replacement for Sierra Marine aftermarket part 18-8366 and several individual Honda OEM seals, including 91251-ZW1-003, 91252-ZW1-003, 91253-ZW1-003, 91254-ZW1-003, and 91255-ZW1-003, offering a complete solution for gearcase resealing.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eEngineered for direct OEM replacement fitting.\u003c\/li\u003e\n\u003cli\u003eSpecifically made for the Honda BF75\/BF90 gearcase.\u003c\/li\u003e\n\u003cli\u003eIncludes all five critical lower unit seals for a full service.\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        \u003cth\u003eNotes\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\u003e18-8366\u003c\/td\u003e\n        \u003ctd\u003eAftermarket Kit\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eHonda\u003c\/td\u003e\n        \u003ctd\u003e91251-ZW1-003\u003c\/td\u003e\n        \u003ctd\u003eDriveshaft Seal\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eHonda\u003c\/td\u003e\n        \u003ctd\u003e91252-ZW1-003\u003c\/td\u003e\n        \u003ctd\u003ePropeller Shaft Seal, Inner\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eHonda\u003c\/td\u003e\n        \u003ctd\u003e91253-ZW1-003\u003c\/td\u003e\n        \u003ctd\u003eShift Shaft Seal\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eHonda\u003c\/td\u003e\n        \u003ctd\u003e91254-ZW1-003\u003c\/td\u003e\n        \u003ctd\u003eDriveshaft Oil Seal\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eHonda\u003c\/td\u003e\n        \u003ctd\u003e91255-ZW1-003\u003c\/td\u003e\n        \u003ctd\u003ePropeller Shaft Seal, Outer\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 kit is specifically designed for certain Honda outboard models. Please check your engine details carefully.\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\u003eHonda\u003c\/td\u003e\n        \u003ctd\u003eBF75\u003c\/td\u003e\n        \u003ctd\u003e75\u003c\/td\u003e\n        \u003ctd\u003e4-Stroke\u003c\/td\u003e\n        \u003ctd\u003e1997–1998+\u003c\/td\u003e\n        \u003ctd\u003e18-8366\u003c\/td\u003e\n        \u003ctd\u003eSierra Marine aftermarket replacement\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eHonda\u003c\/td\u003e\n        \u003ctd\u003eBF90\u003c\/td\u003e\n        \u003ctd\u003e90\u003c\/td\u003e\n        \u003ctd\u003e4-Stroke\u003c\/td\u003e\n        \u003ctd\u003e1997–1998+\u003c\/td\u003e\n        \u003ctd\u003e18-8366\u003c\/td\u003e\n        \u003ctd\u003eSierra Marine aftermarket replacement\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\u003eLower Unit Seal Kit\u003c\/dd\u003e\n  \u003cdt\u003eInstallation\u003c\/dt\u003e\n\u003cdd\u003eDirect replacement\u003c\/dd\u003e\n  \u003cdt\u003eFitting Type\u003c\/dt\u003e\n\u003cdd\u003eDirect OEM replacement\u003c\/dd\u003e\n  \u003cdt\u003eOther Technical Attributes\u003c\/dt\u003e\n\u003cdd\u003eFor Honda BF75\/BF90 gearcase\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;\"\u003e1 x\u003c\/span\u003e Driveshaft Seal (Replaces 91251-ZW1-003)\u003c\/li\u003e\n\u003cli\u003e\n\u003cspan style=\"color:#d0021b;\"\u003e1 x\u003c\/span\u003e Propeller Shaft Seal, Inner (Replaces 91252-ZW1-003)\u003c\/li\u003e\n\u003cli\u003e\n\u003cspan style=\"color:#d0021b;\"\u003e1 x\u003c\/span\u003e Shift Shaft Seal (Replaces 91253-ZW1-003)\u003c\/li\u003e\n\u003cli\u003e\n\u003cspan style=\"color:#d0021b;\"\u003e1 x\u003c\/span\u003e Driveshaft Oil Seal (Replaces 91254-ZW1-003)\u003c\/li\u003e\n\u003cli\u003e\n\u003cspan style=\"color:#d0021b;\"\u003e1 x\u003c\/span\u003e Propeller Shaft Seal, Outer (Replaces 91255-ZW1-003)\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eInstallation Notes\u003c\/h2\u003e\n\u003col\u003e\n\u003cli\u003ePosition the outboard securely and drain the gearcase oil into a suitable container.\u003c\/li\u003e\n\u003cli\u003eRemove the lower unit (gearcase) from the outboard's driveshaft housing.\u003c\/li\u003e\n\u003cli\u003eCarefully remove the propeller shaft and driveshaft bearing carrier assemblies to access the old seals.\u003c\/li\u003e\n\u003cli\u003eExtract the old, worn seals from the gearcase housing and carriers, taking care not to scratch the metal surfaces.\u003c\/li\u003e\n\u003cli\u003eThoroughly clean all seal seating areas, removing any old sealant, corrosion, or debris.\u003c\/li\u003e\n\u003cli\u003eLubricate the new seals with a light coat of marine grease.\u003c\/li\u003e\n\u003cli\u003eUsing a proper seal driver or correctly sized socket, press the new seals into place until they are fully seated.\u003c\/li\u003e\n\u003cli\u003eReinstall the bearing carriers, propeller shaft, and driveshaft.\u003c\/li\u003e\n\u003cli\u003eReattach the lower unit to the outboard, ensuring the driveshaft and water tube align correctly.\u003c\/li\u003e\n\u003cli\u003eRefill the gearcase with the manufacturer-recommended gear lube to the proper level.\u003c\/li\u003e\n\u003cli\u003eCheck for leaks around the drain\/fill screws and shafts before returning to service.\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 this seal kit fits my Honda outboard?\u003c\/summary\u003e\u003cp\u003eThis kit is designed for Honda BF75 (75 HP) and BF90 (90 HP) 4-Stroke models from 1997-1998 and later. Please verify the part numbers (Sierra 18-8366 or OEM seal numbers like 91251-ZW1-003) listed in the compatibility tables against your service manual or existing parts.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eWhat are the signs of a failing lower unit seal?\u003c\/summary\u003e\u003cp\u003eCommon symptoms include a milky, grey, or creamy appearance in your gear lube, which indicates water contamination. You might also notice gear oil leaking from the propeller shaft or driveshaft area. A burning smell from the lower unit can also be a sign of oil loss and overheating.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eIs this a complete kit for a standard lower unit reseal?\u003c\/summary\u003e\u003cp\u003eYes, this kit includes the five primary seals for the driveshaft, shift shaft, and propeller shaft, which are the most common wear items needed for a standard gearcase reseal project.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eHow often should lower unit seals be replaced?\u003c\/summary\u003e\u003cp\u003eIt's good practice to inspect your gear lube at every oil change. Seals should be replaced preventatively every few hundred hours or every few years, depending on usage (especially in saltwater). They must be replaced immediately if you find any signs of water intrusion or oil leakage.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eCan I just replace the one seal that is leaking?\u003c\/summary\u003e\u003cp\u003eWhile possible, it is highly recommended to replace all seals in the kit at the same time. If one seal has failed due to age or wear, the others are likely near the end of their service life as well. Replacing them all at once saves you from having to disassemble the lower unit again in the near future.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eWhat else should I have on hand for the installation?\u003c\/summary\u003e\u003cp\u003eBesides basic hand tools, you will need a new bottle of marine gear lube, potentially new drain\/fill screw gaskets, a seal removal tool (or a flat-head screwdriver used with caution), and a seal installation tool or appropriately sized sockets to press in the new seals without damaging them.\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\u003c\/section\u003e","brand":"SeaSierra","offers":[{"title":"Default Title","offer_id":50723982442811,"sku":"24PSK679R（少pin和一个垫片）","price":161.16,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0826\/8673\/8747\/files\/18-8366.png?v=1763098561","url":"https:\/\/seasierra.com\/products\/lower-unit-seal-kit-fits-honda-bf75-bf90-outboard-motors-replaces-18-8366-91251-zw1-003-91252-zw1-003-91253-zw1-003-91254-zw1-003-91255-zw1-003","provider":"SeaSierra","version":"1.0","type":"link"}