{"product_id":"water-pump-impeller-kit-fits-yamaha-25-40-hp-outboard-motors-replaces-66t-w0078-00","title":"Water Pump Impeller Kit – Fits Yamaha 25-40 HP Outboard Motors (Replaces 66T-W0078-00)","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\u003csection\u003e\n  \u003ch2\u003eProduct Details\u003c\/h2\u003e\n  \u003cp\u003eThis \u003cstrong\u003eWater Pump Impeller Kit – Fits Yamaha 25-40 HP Outboard Motors (Replaces 66T-W0078-00)\u003c\/strong\u003e provides a comprehensive solution for servicing the water pump on Yamaha T25 HP, F30 HP, and F40 HP models manufactured between 2000 and 2005. It is engineered to restore your engine’s cooling system to its original performance.\u003c\/p\u003e\n  \u003cp\u003eThis kit serves as a direct cross-reference for Yamaha part numbers 66T-W0078-00 and 66T-W0078-01-00, as well as Sierra aftermarket equivalents 18-3440 and 18-3413.\u003c\/p\u003e\n  \u003cul\u003e\n    \u003cli\u003eEngineered for direct-fit installation, matching OEM specifications for a reliable repair.\u003c\/li\u003e\n    \u003cli\u003eFeatures a durable, 6-blade impeller designed for optimal water flow and cooling efficiency.\u003c\/li\u003e\n    \u003cli\u003eIncludes all necessary gaskets, seals, and hardware for a complete and professional service.\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.\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\u003eYamaha\u003c\/td\u003e\n          \u003ctd\u003e66T-W0078-00\u003c\/td\u003e\n        \u003c\/tr\u003e\n        \u003ctr\u003e\n          \u003ctd\u003eYamaha\u003c\/td\u003e\n          \u003ctd\u003e66T-W0078-01-00\u003c\/td\u003e\n        \u003c\/tr\u003e\n        \u003ctr\u003e\n          \u003ctd\u003eSierra\u003c\/td\u003e\n          \u003ctd\u003e18-3440\u003c\/td\u003e\n        \u003c\/tr\u003e\n        \u003ctr\u003e\n          \u003ctd\u003eSierra\u003c\/td\u003e\n          \u003ctd\u003e18-3413\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\/year in the table below.\u003c\/p\u003e\n  \u003cp\u003eFor Yamaha owners, please verify your engine's model, horsepower, and year range against this list to ensure an exact match.\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\u003eYamaha\u003c\/td\u003e\n          \u003ctd\u003eT25\u003c\/td\u003e\n          \u003ctd\u003e25\u003c\/td\u003e\n          \u003ctd\u003e4-Stroke\u003c\/td\u003e\n          \u003ctd\u003e2001–2006, 2009\u003c\/td\u003e\n          \u003ctd\u003e66T-W0078-00\u003c\/td\u003e\n          \u003ctd\u003e\u003c\/td\u003e\n        \u003c\/tr\u003e\n        \u003ctr\u003e\n          \u003ctd\u003eYamaha\u003c\/td\u003e\n          \u003ctd\u003eF30\u003c\/td\u003e\n          \u003ctd\u003e30\u003c\/td\u003e\n          \u003ctd\u003e4-Stroke\u003c\/td\u003e\n          \u003ctd\u003e2001–2005\u003c\/td\u003e\n          \u003ctd\u003e66T-W0078-00\u003c\/td\u003e\n          \u003ctd\u003e\u003c\/td\u003e\n        \u003c\/tr\u003e\n        \u003ctr\u003e\n          \u003ctd\u003eYamaha\u003c\/td\u003e\n          \u003ctd\u003eF40\u003c\/td\u003e\n          \u003ctd\u003e40\u003c\/td\u003e\n          \u003ctd\u003e4-Stroke\u003c\/td\u003e\n          \u003ctd\u003e2000–2008\u003c\/td\u003e\n          \u003ctd\u003e66T-W0078-00\u003c\/td\u003e\n          \u003ctd\u003e\u003c\/td\u003e\n        \u003c\/tr\u003e\n        \u003ctr\u003e\n          \u003ctd\u003eYamaha\u003c\/td\u003e\n          \u003ctd\u003e40XMH\u003c\/td\u003e\n          \u003ctd\u003e40\u003c\/td\u003e\n          \u003ctd\u003e2-Stroke\u003c\/td\u003e\n          \u003ctd\u003e2000–2005\u003c\/td\u003e\n          \u003ctd\u003e66T-W0078-00\u003c\/td\u003e\n          \u003ctd\u003e\u003c\/td\u003e\n        \u003c\/tr\u003e\n        \u003ctr\u003e\n          \u003ctd\u003eYamaha\u003c\/td\u003e\n          \u003ctd\u003e40XE\u003c\/td\u003e\n          \u003ctd\u003e40\u003c\/td\u003e\n          \u003ctd\u003e2-Stroke\u003c\/td\u003e\n          \u003ctd\u003e2000–2005\u003c\/td\u003e\n          \u003ctd\u003e66T-W0078-00\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\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\u003eWater Pump Impeller Kit\u003c\/dd\u003e\n    \u003cdt\u003eInstallation\u003c\/dt\u003e\n\u003cdd\u003eDirect Replacement\u003c\/dd\u003e\n    \u003cdt\u003eDimensions\u003c\/dt\u003e\n\u003cdd\u003eImpeller Diameter: 52 mm, Width: 19 mm, Shaft Size: 16 mm\u003c\/dd\u003e\n    \u003cdt\u003eFitting Type\u003c\/dt\u003e\n\u003cdd\u003eKeyway\u003c\/dd\u003e\n    \u003cdt\u003eNumber of Blades\u003c\/dt\u003e\n\u003cdd\u003e6\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 Cartridge Insert (63D-44322-00-00)\u003c\/li\u003e\n    \u003cli\u003e1 x Cartridge Outer Plate (66T-44323-00-00)\u003c\/li\u003e\n    \u003cli\u003e1 x O-Ring (93210-59MG7-00)\u003c\/li\u003e\n    \u003cli\u003e1 x Water Pump Gasket (63D-44316-00-00)\u003c\/li\u003e\n    \u003cli\u003e1 x Woodruff Key (90280-03M03-00)\u003c\/li\u003e\n    \u003cli\u003e1 x Impeller (6H4-44352-02-00)\u003c\/li\u003e\n    \u003cli\u003e\n\u003cspan style=\"color:#d0021b;\"\u003e4 x\u003c\/span\u003e Bolts, With Washer (90119-08M15-00)\u003c\/li\u003e\n    \u003cli\u003e1 x Water Seal Damper 2 (663-44366-00-00)\u003c\/li\u003e\n    \u003cli\u003e1 x Pump Housing Cover (63D-44312-00-00)\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\u003eDisconnect the battery and shift the outboard into neutral. Remove the lower unit mounting bolts.\u003c\/li\u003e\n    \u003cli\u003eCarefully separate the lower unit from the upper housing, being mindful of the shift shaft.\u003c\/li\u003e\n    \u003cli\u003eWith the lower unit on a workbench, unbolt and remove the water pump housing cover.\u003c\/li\u003e\n    \u003cli\u003eRemove the old impeller, key, wear plate, and gaskets. Note the rotational direction of the old impeller blades.\u003c\/li\u003e\n    \u003cli\u003eThoroughly clean all mating surfaces, removing any old gasket residue or corrosion.\u003c\/li\u003e\n    \u003cli\u003eInstall the new gasket, wear plate, and insert cartridge. Lightly grease the interior surfaces.\u003c\/li\u003e\n    \u003cli\u003ePlace the woodruff key in its slot on the driveshaft and slide the new impeller on. Turn the driveshaft clockwise to orient the blades correctly.\u003c\/li\u003e\n    \u003cli\u003eInstall the new O-ring and housing cover, then tighten the bolts to the manufacturer’s specified torque.\u003c\/li\u003e\n    \u003cli\u003eRealign and attach the lower unit to the upper housing, ensuring the driveshaft, shift shaft, and water tube are correctly seated.\u003c\/li\u003e\n    \u003cli\u003eOnce assembled, test the engine using a flush-pro or in water to confirm a strong, steady stream from the tell-tale port.\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 this kit fits my Yamaha outboard?\u003c\/summary\u003e\u003cp\u003eThis kit is designed for specific Yamaha models including the T25 (2001–2006, 2009), F30 (2001–2005), and F40 (2000–2008). To ensure a perfect match, please cross-reference your engine's exact model and year with the compatibility table provided.\u003c\/p\u003e\u003c\/details\u003e\n  \u003cdetails\u003e\u003csummary\u003eWhat are the signs of a failing water pump impeller?\u003c\/summary\u003e\u003cp\u003eCommon symptoms include the engine overheating at idle, a weak or inconsistent water stream from the tell-tale outlet, and a melted pump housing. Upon inspection, a worn impeller may have brittle, cracked, or deformed blades.\u003c\/p\u003e\u003c\/details\u003e\n  \u003cdetails\u003e\u003csummary\u003eHow often should the water pump impeller be replaced?\u003c\/summary\u003e\u003cp\u003eFor preventative maintenance, we recommend replacing the impeller every one to two years, or every 100-200 hours of operation. More frequent replacement may be necessary if operating in sandy, silty, or saltwater conditions.\u003c\/p\u003e\u003c\/details\u003e\n  \u003cdetails\u003e\u003csummary\u003eIs this a complete kit for a water pump service?\u003c\/summary\u003e\u003cp\u003eYes, this is a comprehensive kit containing the impeller, housing, cover, gaskets, plates, key, and all necessary seals and hardware for a standard water pump replacement.\u003c\/p\u003e\u003c\/details\u003e\n  \u003cdetails\u003e\u003csummary\u003eDo I need special tools for installation?\u003c\/summary\u003e\u003cp\u003eStandard workshop tools like a socket set, screwdrivers, and a torque wrench are required. No other highly specialized tools are typically necessary for this service.\u003c\/p\u003e\u003c\/details\u003e\n  \u003cdetails\u003e\u003csummary\u003eCan I install the impeller with blades bent the wrong way?\u003c\/summary\u003e\u003cp\u003eThe impeller blades must curve in the correct direction to pump water effectively. During installation, always turn the driveshaft clockwise as you slide the housing down to ensure the blades are properly oriented.\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\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\n\u003c\/section\u003e","brand":"SeaSierra","offers":[{"title":"Default Title","offer_id":50723806609723,"sku":"17KY012","price":45.5,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0826\/8673\/8747\/files\/17KY0122_c5c9d9ad-10a5-42b2-a350-fcbd411b18ea.jpg?v=1763032268","url":"https:\/\/seasierra.com\/products\/water-pump-impeller-kit-fits-yamaha-25-40-hp-outboard-motors-replaces-66t-w0078-00","provider":"SeaSierra","version":"1.0","type":"link"}