{"product_id":"lower-unit-drain-plug-screw-kit-fits-yamaha-40hp-300hp-replaces-90340-08002-90430-08020-688-45341-10-00","title":"Lower Unit Drain Plug Screw Kit – Fits Yamaha 40HP-300HP (Replaces 90340-08002, 90430-08020, 688-45341-10-00)","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\u003eLower Unit Drain Plug Screw Kit\u003c\/strong\u003e is designed for Yamaha outboard engines ranging from 40HP to 300HP. It provides a complete straight screw plug assembly for lower unit oil maintenance, fitting most engines in this horsepower range. Always verify fitment by matching your original part number rather than relying solely on engine horsepower.\u003c\/p\u003e\n\u003cp\u003eThis kit directly replaces Yamaha OEM part numbers 90340-08002, 90430-08020, and 688-45341-10-00, ensuring cross-compatibility with factory specifications.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eStainless steel construction resists corrosion in marine environments\u003c\/li\u003e\n\u003cli\u003eIncludes both drain plug screw and replacement gasket for complete servicing\u003c\/li\u003e\n\u003cli\u003eDirect fit replacement for routine lower unit maintenance\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\u003eYamaha\u003c\/td\u003e\n        \u003ctd\u003e688-45341-10-00\u003c\/td\u003e\n        \u003ctd\u003eOEM assembly kit\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eYamaha\u003c\/td\u003e\n        \u003ctd\u003e688-45341\u003c\/td\u003e\n        \u003ctd\u003e\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eYamaha\u003c\/td\u003e\n        \u003ctd\u003e90340-08002-00\u003c\/td\u003e\n        \u003ctd\u003eStraight screw plug\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eYamaha\u003c\/td\u003e\n        \u003ctd\u003e90340-08002\u003c\/td\u003e\n        \u003ctd\u003eStraight screw plug\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eYamaha\u003c\/td\u003e\n        \u003ctd\u003e90430-08020\u003c\/td\u003e\n        \u003ctd\u003eOil drain gasket\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eYamaha\u003c\/td\u003e\n        \u003ctd\u003e90430-08003\u003c\/td\u003e\n        \u003ctd\u003eGasket variant\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\u003eRated HP\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\u003eYamaha\u003c\/td\u003e\n        \u003ctd\u003e40HP–300HP\u003c\/td\u003e\n        \u003ctd\u003e688-45341-10-00\u003c\/td\u003e\n        \u003ctd\u003eMost but not all engines in this range; buy by part number\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\u003eDescription\u003c\/dt\u003e\n  \u003cdd\u003eStraight Screw Plug Kit\u003c\/dd\u003e\n  \u003cdt\u003eMaterial\u003c\/dt\u003e\n  \u003cdd\u003eStainless Steel\u003c\/dd\u003e\n  \u003cdt\u003eApplication\u003c\/dt\u003e\n  \u003cdd\u003eLower unit oil drain\u003c\/dd\u003e\n  \u003cdt\u003eCompatibility\u003c\/dt\u003e\n  \u003cdd\u003eYamaha outboard engines, most 40HP–300HP models\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\u003cstrong\u003e1 ×\u003c\/strong\u003e Straight Screw Plug (90340-08002)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e1 ×\u003c\/strong\u003e Lower Unit Oil Drain Gasket (90430-08020)\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eInstallation Notes\u003c\/h2\u003e\n\u003col\u003e\n\u003cli\u003ePosition the boat on a level surface and allow the lower unit to cool completely before servicing.\u003c\/li\u003e\n\u003cli\u003eRemove the old drain plug and gasket from the lower unit housing.\u003c\/li\u003e\n\u003cli\u003eClean the sealing surface thoroughly, removing any old gasket material or debris.\u003c\/li\u003e\n\u003cli\u003eInstall the new gasket onto the drain plug screw.\u003c\/li\u003e\n\u003cli\u003eThread the drain plug by hand to ensure proper alignment and prevent cross-threading.\u003c\/li\u003e\n\u003cli\u003eTighten the plug to manufacturer specifications using a torque wrench—do not over-tighten.\u003c\/li\u003e\n\u003cli\u003eInspect for leaks after refilling the lower unit with fresh gear oil.\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 kit fits my Yamaha outboard?\u003c\/summary\u003e\u003cp\u003eCompare the part numbers listed (90340-08002, 90430-08020, 688-45341-10-00) with your existing drain plug. While this kit fits most Yamaha 40HP–300HP engines, always verify by part number rather than horsepower alone.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eCan I reuse the old gasket?\u003c\/summary\u003e\u003cp\u003eNo. The gasket is a single-use component designed to crush and form a seal. Always replace it during lower unit service to prevent oil leaks.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eWhat torque specification should I use?\u003c\/summary\u003e\u003cp\u003eConsult your engine's service manual for exact torque values. Typical specifications range from 10–15 ft-lbs, but over-tightening can strip threads or crack the housing.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eHow often should I replace the drain plug and gasket?\u003c\/summary\u003e\u003cp\u003eReplace the gasket every time you service the lower unit oil, typically every 100 hours of operation or annually. Inspect the drain plug for damage or thread wear; replace if worn.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eWhat are signs of a failing drain plug seal?\u003c\/summary\u003e\u003cp\u003eVisible oil seepage around the plug, low gear oil levels between service intervals, or water contamination in the lower unit oil indicate a compromised seal.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eIs the plug magnetic?\u003c\/summary\u003e\u003cp\u003eThis kit features a standard straight screw plug. Some Yamaha engines use magnetic drain plugs to capture metal particles; confirm your engine's original specification before ordering.\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":51025914626363,"sku":"25GK073","price":16.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0826\/8673\/8747\/files\/12_a0189a38-0798-43c2-a7d6-d5f860e1226e.jpg?v=1772975096","url":"https:\/\/seasierra.com\/products\/lower-unit-drain-plug-screw-kit-fits-yamaha-40hp-300hp-replaces-90340-08002-90430-08020-688-45341-10-00","provider":"SeaSierra","version":"1.0","type":"link"}