{"product_id":"water-pump-impeller-repair-kit-fits-mercury-marine-4-9-8-hp-replaces-47-89981q1-47-89981t1-47-89981t2","title":"Water Pump Impeller Repair Kit – Fits Mercury Marine 4–9.8 HP (Replaces 47-89981Q1, 47-89981T1, 47-89981T2)","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 \u003cstrong\u003eWater Pump Impeller Repair Kit\u003c\/strong\u003e is designed for Mercury and Mariner 4, 4.5, 6, 7.5, and 9.8 HP 2-stroke outboard motors manufactured between 1975 and 1986. The kit provides all the necessary components for a complete overhaul of the lower unit water pump to restore cooling performance.\u003c\/p\u003e\n\u003cp\u003eIt serves as a direct replacement for Mercury part numbers 47-89981Q1, 47-89981T1, and 47-89981T2, as well as Sierra 18-3239, GLM 12270, and Soxa Marine 18KM001.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eInstalls in the lower unit housing.\u003c\/li\u003e\n\u003cli\u003eFeatures a durable neoprene impeller with a brass hub for reliable performance.\u003c\/li\u003e\n\u003cli\u003eIncludes a marine-grade SS316 stainless steel wear plate and essential seals.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2\u003ePart Number Matrix\u003c\/h2\u003e\n\u003cp\u003eUse this matrix to confirm equivalent references across OEM and aftermarket brands.\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\u003eMercury\u003c\/td\u003e\n        \u003ctd\u003e47-89981Q1\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eMercury\u003c\/td\u003e\n        \u003ctd\u003e47-89981T1\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eMercury\u003c\/td\u003e\n        \u003ctd\u003e47-89981T2\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eSierra\u003c\/td\u003e\n        \u003ctd\u003e18-3239\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eGLM\u003c\/td\u003e\n        \u003ctd\u003e12270\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eSoxa Marine\u003c\/td\u003e\n        \u003ctd\u003e18KM001\u003c\/td\u003e\n      \u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\u003c\/div\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 Mercury\/Mariner Outboards, it is critical to verify the serial number (S\/N) range to ensure correct fitment. This kit is not compatible with all engines in the listed horsepower range.\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\u003eMercury 4 HP\u003c\/td\u003e\n        \u003ctd\u003e4\u003c\/td\u003e\n        \u003ctd\u003e2-Stroke\u003c\/td\u003e\n        \u003ctd\u003e1975–1986\u003c\/td\u003e\n        \u003ctd\u003e47-89981Q1\u003c\/td\u003e\n        \u003ctd\u003eFor S\/N 5595532 \u0026amp; Up U.S.\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eMercury 4.5 HP\u003c\/td\u003e\n        \u003ctd\u003e4.5\u003c\/td\u003e\n        \u003ctd\u003e2-Stroke\u003c\/td\u003e\n        \u003ctd\u003e1975–1986\u003c\/td\u003e\n        \u003ctd\u003e47-89981Q1\u003c\/td\u003e\n        \u003ctd\u003eFor S\/N 5595532 \u0026amp; Up 1 cylinder\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eMercury 6 HP\u003c\/td\u003e\n        \u003ctd\u003e6\u003c\/td\u003e\n        \u003ctd\u003e2-Stroke\u003c\/td\u003e\n        \u003ctd\u003e1975–1986\u003c\/td\u003e\n        \u003ctd\u003e47-89981Q1\u003c\/td\u003e\n        \u003ctd\u003eFor S\/N 1916139 through 2529894\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eMercury 7.5 HP\u003c\/td\u003e\n        \u003ctd\u003e7.5\u003c\/td\u003e\n        \u003ctd\u003e2-Stroke\u003c\/td\u003e\n        \u003ctd\u003e1975–1986\u003c\/td\u003e\n        \u003ctd\u003e47-89981Q1\u003c\/td\u003e\n        \u003ctd\u003eModel 75, S\/N 5206550 \u0026amp; Up\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eMercury 9.8 HP\u003c\/td\u003e\n        \u003ctd\u003e9.8\u003c\/td\u003e\n        \u003ctd\u003e2-Stroke\u003c\/td\u003e\n        \u003ctd\u003e1975–1986\u003c\/td\u003e\n        \u003ctd\u003e47-89981Q1\u003c\/td\u003e\n        \u003ctd\u003eModel Merc 110, S\/N 5206550 \u0026amp; Up\u003c\/td\u003e\n      \u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\u003c\/div\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\u003eLower Unit\u003c\/dd\u003e\n  \u003cdt\u003eMaterial\u003c\/dt\u003e\n\u003cdd\u003eNeoprene Impeller with Brass Hub, Marine Grade SS316 Wear Plate\u003c\/dd\u003e\n  \u003cdt\u003eImpeller Blades\u003c\/dt\u003e\n\u003cdd\u003e6\u003c\/dd\u003e\n  \u003cdt\u003eImpeller Height\u003c\/dt\u003e\n\u003cdd\u003e14.4 mm (0.57 inches)\u003c\/dd\u003e\n  \u003cdt\u003eOverall Diameter\u003c\/dt\u003e\n\u003cdd\u003e32.0 mm (1.26 inches)\u003c\/dd\u003e\n  \u003cdt\u003eShaft Diameter\u003c\/dt\u003e\n\u003cdd\u003e11.0 mm (0.456 inches)\u003c\/dd\u003e\n  \u003cdt\u003eWeight\u003c\/dt\u003e\n\u003cdd\u003e11 g (0.45 oz)\u003c\/dd\u003e\n  \u003cdt\u003eHousing Material\u003c\/dt\u003e\n\u003cdd\u003eMarine Grade SS316\u003c\/dd\u003e\n  \u003cdt\u003eWarranty\u003c\/dt\u003e\n\u003cdd\u003e1 Year\u003c\/dd\u003e\n\u003c\/dl\u003e\n\u003ch2\u003eWhat’s in the Box\u003c\/h2\u003e\n\u003cul\u003e\n  \u003cli\u003e\u003cspan style=\"color:#d0021b;\"\u003e1 x Impeller (47-89981\/18-3039)\u003c\/span\u003e\u003c\/li\u003e\n  \u003cli\u003e1 x Wear Plate (46895)\u003c\/li\u003e\n  \u003cli\u003e1 x Key, Woodruff Impeller\u003c\/li\u003e\n  \u003cli\u003e1 x Sleeve, Guide Water Inlet Tube\u003c\/li\u003e\n  \u003cli\u003e1 x Seal (700-85651)\u003c\/li\u003e\n  \u003cli\u003e2 x O-ring (700-81230, 700-81090)\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2\u003eInstallation Notes\u003c\/h2\u003e\n\u003col\u003e\n  \u003cli\u003eDisconnect the spark plug wires and shift the engine into neutral.\u003c\/li\u003e\n  \u003cli\u003eRemove the bolts securing the lower unit (gearcase) and carefully drop it down.\u003c\/li\u003e\n  \u003cli\u003eUnbolt and remove the water pump housing cover to access the old impeller.\u003c\/li\u003e\n  \u003cli\u003eTake note of the old impeller's blade orientation before removing it. Remove the Woodruff key from the driveshaft.\u003c\/li\u003e\n  \u003cli\u003eClean the housing interior and inspect the wear plate and housing for scoring or cracks. Replace if damaged.\u003c\/li\u003e\n  \u003cli\u003eInstall the new Woodruff key, then slide the new impeller onto the driveshaft while twisting it in the direction of engine rotation to properly seat the blades.\u003c\/li\u003e\n  \u003cli\u003eInstall the new wear plate and O-rings\/seals. Re-install the housing.\u003c\/li\u003e\n  \u003cli\u003eLightly grease the driveshaft splines and reinstall the lower unit, ensuring the water tube and shift shaft align correctly.\u003c\/li\u003e\n\u003c\/ol\u003e\n\u003ch2\u003eTroubleshooting \u0026amp; FAQ\u003c\/h2\u003e\n\u003cdetails\u003e\u003csummary\u003eWill this kit fit my 5 HP Mercury outboard?\u003c\/summary\u003e\u003cp\u003eNo. Multiple sources confirm this impeller kit will NOT fit 5 HP Mercury or Mariner engines. Please verify your engine's horsepower and serial number against the compatibility chart.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eIs the impeller shaft size important?\u003c\/summary\u003e\u003cp\u003eYes, it is critical. This impeller is designed for a driveshaft diameter of 11.0 mm (0.456 inches). Using an incorrect size will result in pump failure and potential engine damage.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eWhy is my engine's serial number so important?\u003c\/summary\u003e\u003cp\u003eManufacturers often make mid-year changes to engine components. This kit is only verified to fit the specific serial number ranges listed in the compatibility table. Always check your engine's S\/N before ordering.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eWhen should I replace my water pump impeller?\u003c\/summary\u003e\u003cp\u003eFor preventative maintenance, it is recommended to replace the impeller every 1-2 years or every 100-200 hours of operation, especially if used frequently in saltwater or silty conditions.\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 a weak or nonexistent water stream from the \"telltale\" outlet, engine overheating alerts, or a physically brittle, cracked, or deformed impeller upon inspection.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eIs this an OEM part or an aftermarket one?\u003c\/summary\u003e\u003cp\u003eThis listing is an aftermarket replacement (not OEM). It is built to OEM-level specifications with comparable materials and manufactured in an ISO 9002 facility, with batch inspections for quality and consistency.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eHow fast do you ship and what is the cost?\u003c\/summary\u003e\u003cp\u003eWe ship worldwide quickly—typical transit is 5–15 days. Standard shipping is free, and any available expedited options will appear at checkout.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eWhat is the warranty and return policy?\u003c\/summary\u003e\u003cp\u003eThis part is covered 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 for unused items in their original condition. See our policy page or reach out for instructions.\u003c\/p\u003e\u003c\/details\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\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":50723968909627,"sku":"18KM001-QM","price":19.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0826\/8673\/8747\/files\/18KM001-QM.png?v=1763038736","url":"https:\/\/seasierra.com\/products\/water-pump-impeller-repair-kit-fits-mercury-marine-4-9-8-hp-replaces-47-89981q1-47-89981t1-47-89981t2","provider":"SeaSierra","version":"1.0","type":"link"}