{"title":"Tohatsu 4-Stroke 7.5-10HP Outboard Engine Parts","description":"\u003csection id=\"hero\" style=\"padding:16px; border:1px solid #e5e7eb; border-radius:8px;\"\u003e\n  \u003cp\u003eThis page is dedicated to Tohatsu 4-Stroke 7.5-10HP outboard engines. Use it to find compatible parts and service information, including routine maintenance tips, common replacement items, and troubleshooting guidance. You can also browse the main Tohatsu collection any time. Scroll to the bottom of this page to start browsing parts for this engine, and on the collection page use the “Filter \u0026amp; Sort” controls to narrow results by horsepower, year range, and part category.\u003c\/p\u003e\n  \u003cp\u003e\u003ca href=\"https:\/\/seasierra.com\/collections\/tohatsu-outboard-parts\" style=\"display:inline-block; padding:10px 14px; background:#0d6efd; color:#fff; text-decoration:none; border-radius:6px;\"\u003eBrowse All Tohatsu Parts\u003c\/a\u003e\u003c\/p\u003e\n\u003c\/section\u003e\n\n\u003csection id=\"identify-model\"\u003e\n  \u003ch2\u003eHow to Identify Your 7.5-10HP Model\u003c\/h2\u003e\n  \u003cul\u003e\n    \u003cli\u003eCheck the serial\/nameplate on the transom or clamp bracket. It typically lists the model designation (e.g., MFS8, MFS9.8, MFS9.9) and a serial number.\u003c\/li\u003e\n    \u003cli\u003eRead the suffix characters: they often indicate shaft length (S=15 in, L=20 in), control type (tiller vs. remote), and other configuration details.\u003c\/li\u003e\n    \u003cli\u003eConfirm it’s a 4-stroke: look for an engine oil fill\/dipstick and 4-stroke labeling on the cowl. These portable models are typically twin-cylinder 4-strokes.\u003c\/li\u003e\n    \u003cli\u003eNote year range if available; if not, the serial and model code together are usually sufficient to confirm parts compatibility.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\u003c\/section\u003e\n\n\u003csection id=\"engine-overview\"\u003e\n  \u003ch2\u003eEngine Overview\u003c\/h2\u003e\n  \u003ch3\u003ePortable 4‑Stroke (7.5–10HP class)\u003c\/h3\u003e\n  \u003ctable style=\"width:100%; border-collapse:collapse;\"\u003e\n    \u003cthead\u003e\n      \u003ctr\u003e\n        \u003cth style=\"text-align:left; border-bottom:1px solid #e5e7eb; padding:8px;\"\u003eFeature\u003c\/th\u003e\n        \u003cth style=\"text-align:left; border-bottom:1px solid #e5e7eb; padding:8px;\"\u003eDescription\u003c\/th\u003e\n      \u003c\/tr\u003e\n    \u003c\/thead\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n        \u003ctd style=\"padding:8px;\"\u003eConfiguration\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;\"\u003eTypically inline 2‑cylinder, 4‑stroke portable outboards designed for small boats and tenders.\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd style=\"padding:8px;\"\u003eCommon Models\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;\"\u003eExamples include MFS8, MFS9.8, and MFS9.9 designations (varies by year and region).\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd style=\"padding:8px;\"\u003eAdvantages\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;\"\u003eLightweight and fuel‑efficient; easy starting; smooth trolling; simple annual service requirements.\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd style=\"padding:8px;\"\u003eNotes\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;\"\u003eConfirm shaft length and control type before ordering. Some variants may differ in carburetion\/EFI and electrical options; match parts by model code and serial.\u003c\/td\u003e\n      \u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\u003c\/section\u003e\n\n\u003csection id=\"service-kits\"\u003e\n  \u003ch2\u003eRoutine Maintenance \u0026amp; Service Parts\u003c\/h2\u003e\n  \u003cp\u003eIntervals below are general guidelines for portable 4‑stroke Tohatsu engines. Always follow the maintenance schedule and procedures in your official owner’s\/service manual.\u003c\/p\u003e\n  \u003ctable style=\"width:100%; border-collapse:collapse;\"\u003e\n    \u003cthead\u003e\n      \u003ctr\u003e\n        \u003cth style=\"text-align:left; border-bottom:1px solid #e5e7eb; padding:8px;\"\u003eItem\u003c\/th\u003e\n        \u003cth style=\"text-align:left; border-bottom:1px solid #e5e7eb; padding:8px;\"\u003eInterval*\u003c\/th\u003e\n        \u003cth style=\"text-align:left; border-bottom:1px solid #e5e7eb; padding:8px;\"\u003eRemarks\u003c\/th\u003e\n        \u003cth style=\"text-align:left; border-bottom:1px solid #e5e7eb; padding:8px;\"\u003eParts Link\u003c\/th\u003e\n      \u003c\/tr\u003e\n    \u003c\/thead\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n        \u003ctd style=\"padding:8px;\"\u003eEngine oil + filter (if equipped)\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;\"\u003eInitial 20 hours, then every 100 hours or annually\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;\"\u003eUse marine 4‑stroke oil; some models use an external spin‑on filter, others use an internal screen—check your model.\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;\"\u003e\u003ca href=\"https:\/\/seasierra.com\/collections\/oil-filters\"\u003eOil Filters\u003c\/a\u003e\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd style=\"padding:8px;\"\u003eLower unit gear oil\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;\"\u003eEvery 100 hours or annually\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;\"\u003eInspect for metal or milky oil (water intrusion). Reseal if contamination is found.\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;\"\u003e\u003ca href=\"https:\/\/seasierra.com\/collections\/tohatsu-outboard-parts\"\u003eTohatsu Outboard Parts\u003c\/a\u003e\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd style=\"padding:8px;\"\u003eSpark plugs\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;\"\u003eInspect 100 hours; replace 200 hours or as needed\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;\"\u003eCheck gap and condition; replace if fouled, worn, or out of spec.\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;\"\u003e\u003ca href=\"https:\/\/seasierra.com\/collections\/spark-plug\"\u003eSpark plug\u003c\/a\u003e\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd style=\"padding:8px;\"\u003eFuel filter \/ in‑line filter\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;\"\u003eInspect 50–100 hours; replace 100–200 hours\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;\"\u003eDrain\/replace if water or debris is present; keep primer bulb and lines in good condition.\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;\"\u003e\u003ca href=\"https:\/\/seasierra.com\/collections\/fuel-filters-1\"\u003eFuel Filters\u003c\/a\u003e\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd style=\"padding:8px;\"\u003eWater pump impeller \/ kit\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;\"\u003eInspect annually; replace every 2–3 seasons or 200 hours\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;\"\u003eEssential for proper cooling and tell‑tale stream; replace sooner if weak flow or overheat alarm occurs.\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;\"\u003e\u003ca href=\"https:\/\/seasierra.com\/collections\/tohatsu-water-pump-repair-kits\"\u003eTohatsu Water Pump Repair Kits\u003c\/a\u003e\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd style=\"padding:8px;\"\u003eAnodes (corrosion protection)\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;\"\u003eInspect every 50 hours \/ quarterly; replace when 50% eroded\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;\"\u003eNever paint anodes; ensure all bonding\/ground wires are intact.\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;\"\u003e\u003ca href=\"https:\/\/seasierra.com\/collections\/anodes\"\u003eAnodes\u003c\/a\u003e\u003c\/td\u003e\n      \u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n  \u003cp style=\"font-size:12px; color:#6b7280;\"\u003e*Intervals may vary by year\/model and usage (saltwater, commercial, extended trolling). Follow your model’s service manual.\u003c\/p\u003e\n\u003c\/section\u003e\n\n\u003csection id=\"common-parts\"\u003e\n  \u003ch2\u003eFrequently Used Parts Categories\u003c\/h2\u003e\n  \u003cul\u003e\n    \u003cli\u003eRoutine Service: \u003ca href=\"https:\/\/seasierra.com\/collections\/oil-filters\"\u003eOil Filters\u003c\/a\u003e\n\u003c\/li\u003e\n    \u003cli\u003eCooling System: \u003ca href=\"https:\/\/seasierra.com\/collections\/tohatsu-water-pump-repair-kits\"\u003eTohatsu Water Pump Repair Kits\u003c\/a\u003e\n\u003c\/li\u003e\n    \u003cli\u003eGearcase \u0026amp; Seals: \u003ca href=\"https:\/\/seasierra.com\/collections\/tohatsu-lower-unit-seal-kits\"\u003eTohatsu Lower Unit Seal Kits\u003c\/a\u003e\n\u003c\/li\u003e\n    \u003cli\u003ePropellers: \u003ca href=\"https:\/\/seasierra.com\/collections\/propellers\"\u003ePropellers\u003c\/a\u003e\n\u003c\/li\u003e\n    \u003cli\u003eFuel System: \u003ca href=\"https:\/\/seasierra.com\/collections\/fuel-filters-1\"\u003eFuel Filters\u003c\/a\u003e\n\u003c\/li\u003e\n    \u003cli\u003eIgnition \/ Electrical: \u003ca href=\"https:\/\/seasierra.com\/collections\/electrical-items\"\u003eElectrical Items\u003c\/a\u003e and \u003ca href=\"https:\/\/seasierra.com\/collections\/spark-plug\"\u003eSpark plug\u003c\/a\u003e\n\u003c\/li\u003e\n    \u003cli\u003eCorrosion Protection: \u003ca href=\"https:\/\/seasierra.com\/collections\/anodes\"\u003eAnodes\u003c\/a\u003e\n\u003c\/li\u003e\n  \u003c\/ul\u003e\n\u003c\/section\u003e\n\n\u003csection id=\"troubleshooting\"\u003e\n  \u003ch2\u003eCommon Symptoms \u0026amp; Quick Checks\u003c\/h2\u003e\n  \u003ctable style=\"width:100%; border-collapse:collapse;\"\u003e\n    \u003cthead\u003e\n      \u003ctr\u003e\n        \u003cth style=\"text-align:left; border-bottom:1px solid #e5e7eb; padding:8px;\"\u003eSymptom\u003c\/th\u003e\n        \u003cth style=\"text-align:left; border-bottom:1px solid #e5e7eb; padding:8px;\"\u003eCheck First\u003c\/th\u003e\n        \u003cth style=\"text-align:left; border-bottom:1px solid #e5e7eb; padding:8px;\"\u003eRelated Parts\u003c\/th\u003e\n      \u003c\/tr\u003e\n    \u003c\/thead\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n        \u003ctd style=\"padding:8px;\"\u003eWeak tell‑tale stream or overheat alarm\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;\"\u003eInspect intake screens for blockage; verify primer bulb firmness; check that the engine is fully lowered; confirm impeller age.\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;\"\u003eWater pump kit, thermostat, intake screen, anodes\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd style=\"padding:8px;\"\u003ePoor acceleration or loss of power\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;\"\u003eCheck propeller for damage or excessive pitch; confirm fresh fuel; inspect\/replace fuel filter; check spark plugs.\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;\"\u003ePropeller, fuel filter, spark plugs, fuel lines\/primer bulb\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd style=\"padding:8px;\"\u003eHard starting \/ rough idle\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;\"\u003eVerify choke\/enrichment operation; check for stale fuel; inspect spark plug gap\/condition; look for air leaks in fuel line.\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;\"\u003eSpark plugs, fuel filter, fuel hose\/connector, carb clean or EFI service (as applicable)\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd style=\"padding:8px;\"\u003eGearcase noise or milky gear oil\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;\"\u003eDrain and inspect gear oil; look for water intrusion; check for fishing line behind prop; verify seals.\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;\"\u003eGear oil service, lower unit seal kit, prop shaft seals, bearings (inspection)\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd style=\"padding:8px;\"\u003eBlue\/white smoke on 4‑stroke\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;\"\u003eConfirm oil level is not overfilled; keep engine upright during storage; check crankcase breather routing.\u003c\/td\u003e\n        \u003ctd style=\"padding:8px;\"\u003eEngine oil service, breather\/PCV inspection\u003c\/td\u003e\n      \u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\u003c\/section\u003e\n\n\u003csection id=\"faq\"\u003e\n  \u003ch2\u003eFAQs\u003c\/h2\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eAre parts interchangeable between different years or platforms?\u003c\/summary\u003e\n    \u003cp\u003eSome fasteners and service items may carry across years, but many components depend on the exact model code, serial range, and configuration (shaft length, tiller vs. remote, carb vs. EFI). Always match by model code and serial for best results.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eWhen should I replace the impeller?\u003c\/summary\u003e\n    \u003cp\u003eInspect yearly and replace every 2–3 seasons or ~200 hours. Replace sooner if you notice a weak tell‑tale, overheat alarms, or if the engine was run dry.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eHow often should I change the lower unit gear oil?\u003c\/summary\u003e\n    \u003cp\u003eAs a rule of thumb, every 100 hours or annually. Inspect after the first 20 hours on a new or newly serviced gearcase. If oil looks milky or metallic, service immediately and consider a seal kit.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eWhat information do you need to confirm part compatibility?\u003c\/summary\u003e\n    \u003cp\u003ePlease provide the full model code, serial number, shaft length (S\/L), and control type (tiller\/remote). A photo of the nameplate and the part being replaced is also very helpful.\u003c\/p\u003e\n  \u003c\/details\u003e\n\u003c\/section\u003e\n\n\u003csection id=\"cta\" style=\"padding:16px; border-top:1px solid #e5e7eb;\"\u003e\n  \u003cp\u003eReady to find parts? Browse the main Tohatsu collection and filter by horsepower, model, and category.\u003c\/p\u003e\n  \u003cp\u003e\u003ca href=\"https:\/\/seasierra.com\/collections\/tohatsu-outboard-parts\" style=\"display:inline-block; padding:10px 14px; background:#0d6efd; color:#fff; text-decoration:none; border-radius:6px;\"\u003eShop Tohatsu Outboard Parts\u003c\/a\u003e\u003c\/p\u003e\n  \u003cp style=\"font-size:12px; color:#6b7280;\"\u003eIf you’re unsure about your model, send us a photo of the nameplate and the part you need and we’ll help verify compatibility.\u003c\/p\u003e\n\u003c\/section\u003e","products":[{"product_id":"water-pump-impeller-fits-mercury-tohatsu-8-20-hp-4-stroke-outboards-replaces-47-803748","title":"Aftermarket Water Pump Impeller for Mercury\/Mariner and Tohatsu\/Nissan Outboards – 2-Stroke 9.9–18 HP, 4-Stroke 9.9–20 HP","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 aftermarket \u003cstrong\u003ewater pump impeller\u003c\/strong\u003e is designed for selected Mercury\/Mariner and Tohatsu\/Nissan marine outboards. The company application data covers Tohatsu\/Nissan 2-stroke 9.9, 15, and 18 HP engines; Tohatsu 4-stroke MFS9.9, MFS15, and MFS18 engines; Tohatsu 4-stroke 20 HP engines; and Mercury\/Mariner 4-stroke 9.9 HP 209cc, 15 HP, and 20 HP applications.\u003c\/p\u003e\n  \u003cp\u003eUse the reference numbers and model information below as a fitment aid. Outboard water pump components can vary by model family, production year, and serial-number range, so confirm the existing impeller or manufacturer part number before ordering.\u003c\/p\u003e\n  \u003cul\u003e\n    \u003cli\u003eReplacement water pump impeller for selected 2-stroke and 4-stroke outboards.\u003c\/li\u003e\n    \u003cli\u003eAftermarket replacement listed under Sierra reference \u003cstrong\u003e18-8921\u003c\/strong\u003e.\u003c\/li\u003e\n    \u003cli\u003eSold as \u003cstrong\u003eone impeller only\u003c\/strong\u003e; an impeller key is not included unless specifically stated by the seller.\u003c\/li\u003e\n    \u003cli\u003eNot an OEM component. Brand names and part numbers are used only to identify intended applications and reference compatibility.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003ch2\u003ePart Number Matrix\u003c\/h2\u003e\n  \u003cp\u003eThe following manufacturer and aftermarket references are listed for cross-referencing. A reference number alone does not replace confirmation of the complete engine model and serial-number conditions.\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 or Source\u003c\/th\u003e\n\u003cth\u003eReference Number\u003c\/th\u003e\n\u003cth\u003eUse\u003c\/th\u003e\n\u003c\/tr\u003e\n      \u003c\/thead\u003e\n      \u003ctbody\u003e\n        \u003ctr\u003e\n\u003ctd\u003eTohatsu\u003c\/td\u003e\n\u003ctd\u003e334-65021-0\u003c\/td\u003e\n\u003ctd\u003eManufacturer reference\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003ctd\u003eTohatsu\u003c\/td\u003e\n\u003ctd\u003e334650210M\u003c\/td\u003e\n\u003ctd\u003eManufacturer reference format\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003ctd\u003eMercury Marine\u003c\/td\u003e\n\u003ctd\u003e47-803748\u003c\/td\u003e\n\u003ctd\u003eManufacturer reference\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003ctd\u003eMercury Marine\u003c\/td\u003e\n\u003ctd\u003e8M0135803\u003c\/td\u003e\n\u003ctd\u003eManufacturer reference\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003ctd\u003eMercury Marine\u003c\/td\u003e\n\u003ctd\u003e8M0214944\u003c\/td\u003e\n\u003ctd\u003eAdditional listed reference\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003ctd\u003eMercury Marine\u003c\/td\u003e\n\u003ctd\u003e803748\u003c\/td\u003e\n\u003ctd\u003eAdditional listed reference\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003ctd\u003eMercury Marine\u003c\/td\u003e\n\u003ctd\u003e803748K01\u003c\/td\u003e\n\u003ctd\u003eAdditional listed reference\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003ctd\u003eSierra\u003c\/td\u003e\n\u003ctd\u003e18-8921\u003c\/td\u003e\n\u003ctd\u003eAftermarket reference\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003ctd\u003eEvinrude\/Johnson\/OMC\/BRP\u003c\/td\u003e\n\u003ctd\u003e5040046\u003c\/td\u003e\n\u003ctd\u003eAdditional listed reference\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\u003eCompatibility is organized by engine family and stroke type. Confirm the exact model and serial number before installation.\u003c\/p\u003e\n  \u003cdiv class=\"ss-table-wrap\"\u003e\n    \u003ctable class=\"ss-table\" aria-label=\"Tohatsu and Nissan Compatibility\"\u003e\n      \u003cthead\u003e\n        \u003ctr\u003e\n          \u003cth\u003eBrand\u003c\/th\u003e\n\u003cth\u003eModel or Application\u003c\/th\u003e\n\u003cth\u003eRated HP\u003c\/th\u003e\n\u003cth\u003eStroke\u003c\/th\u003e\n\u003cth\u003eReference\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\u003eTohatsu\/Nissan\u003c\/td\u003e\n\u003ctd\u003eM9.9, NS9.9 and related applications\u003c\/td\u003e\n\u003ctd\u003e9.9\u003c\/td\u003e\n\u003ctd\u003e2-Stroke\u003c\/td\u003e\n\u003ctd\u003e334-65021-0\u003cbr\u003e334650210M\u003c\/td\u003e\n\u003ctd\u003eConfirm the exact model designation.\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003ctd\u003eTohatsu\/Nissan\u003c\/td\u003e\n\u003ctd\u003eM15, NS15 and related applications\u003c\/td\u003e\n\u003ctd\u003e15\u003c\/td\u003e\n\u003ctd\u003e2-Stroke\u003c\/td\u003e\n\u003ctd\u003e334-65021-0\u003cbr\u003e334650210M\u003c\/td\u003e\n\u003ctd\u003eConfirm the exact model designation.\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003ctd\u003eTohatsu\/Nissan\u003c\/td\u003e\n\u003ctd\u003eM18, NS18 and related applications\u003c\/td\u003e\n\u003ctd\u003e18\u003c\/td\u003e\n\u003ctd\u003e2-Stroke\u003c\/td\u003e\n\u003ctd\u003e334-65021-0\u003cbr\u003e334650210M\u003c\/td\u003e\n\u003ctd\u003eConfirm the exact model designation.\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003ctd\u003eTohatsu\u003c\/td\u003e\n\u003ctd\u003eMFS9.9\u003c\/td\u003e\n\u003ctd\u003e9.9\u003c\/td\u003e\n\u003ctd\u003e4-Stroke\u003c\/td\u003e\n\u003ctd\u003e334-65021-0\u003cbr\u003e334650210M\u003c\/td\u003e\n\u003ctd\u003eApplication listed in the company data.\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003ctd\u003eTohatsu\u003c\/td\u003e\n\u003ctd\u003eMFS15\u003c\/td\u003e\n\u003ctd\u003e15\u003c\/td\u003e\n\u003ctd\u003e4-Stroke\u003c\/td\u003e\n\u003ctd\u003e334-65021-0\u003cbr\u003e334650210M\u003c\/td\u003e\n\u003ctd\u003eApplication listed in the company data.\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003ctd\u003eTohatsu\u003c\/td\u003e\n\u003ctd\u003eMFS18\u003c\/td\u003e\n\u003ctd\u003e18\u003c\/td\u003e\n\u003ctd\u003e4-Stroke\u003c\/td\u003e\n\u003ctd\u003e334-65021-0\u003cbr\u003e334650210M\u003c\/td\u003e\n\u003ctd\u003eApplication listed in the company data.\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003ctd\u003eTohatsu\u003c\/td\u003e\n\u003ctd\u003e20 HP applications\u003c\/td\u003e\n\u003ctd\u003e20\u003c\/td\u003e\n\u003ctd\u003e4-Stroke\u003c\/td\u003e\n\u003ctd\u003e334-65021-0\u003cbr\u003e334650210M\u003c\/td\u003e\n\u003ctd\u003eConfirm the exact model and serial number.\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003c\/tbody\u003e\n    \u003c\/table\u003e\n  \u003c\/div\u003e\n\n  \u003cdiv class=\"ss-table-wrap\"\u003e\n    \u003ctable class=\"ss-table\" aria-label=\"Mercury and Mariner Compatibility\"\u003e\n      \u003cthead\u003e\n        \u003ctr\u003e\n          \u003cth\u003eBrand\u003c\/th\u003e\n\u003cth\u003eModel or Application\u003c\/th\u003e\n\u003cth\u003eRated HP\u003c\/th\u003e\n\u003cth\u003eStroke\u003c\/th\u003e\n\u003cth\u003eReference\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\/Mariner\u003c\/td\u003e\n\u003ctd\u003e9.9 HP 209cc applications\u003c\/td\u003e\n\u003ctd\u003e9.9\u003c\/td\u003e\n\u003ctd\u003e4-Stroke\u003c\/td\u003e\n\u003ctd\u003e47-803748\u003cbr\u003e8M0135803\u003c\/td\u003e\n\u003ctd\u003eConfirm the 209cc engine configuration.\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003ctd\u003eMercury\/Mariner\u003c\/td\u003e\n\u003ctd\u003e15 HP applications\u003c\/td\u003e\n\u003ctd\u003e15\u003c\/td\u003e\n\u003ctd\u003e4-Stroke\u003c\/td\u003e\n\u003ctd\u003e47-803748\u003cbr\u003e8M0135803\u003c\/td\u003e\n\u003ctd\u003eConfirm the exact model and serial number.\u003c\/td\u003e\n\u003c\/tr\u003e\n        \u003ctr\u003e\n\u003ctd\u003eMercury\/Mariner\u003c\/td\u003e\n\u003ctd\u003e20 HP applications\u003c\/td\u003e\n\u003ctd\u003e20\u003c\/td\u003e\n\u003ctd\u003e4-Stroke\u003c\/td\u003e\n\u003ctd\u003e47-803748\u003cbr\u003e8M0135803\u003c\/td\u003e\n\u003ctd\u003eConfirm the exact model and serial number.\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003c\/tbody\u003e\n    \u003c\/table\u003e\n  \u003c\/div\u003e\n\n  \u003ch2\u003eTechnical Information\u003c\/h2\u003e\n  \u003cdl\u003e\n    \u003cdt\u003eProduct Type\u003c\/dt\u003e\n    \u003cdd\u003eWater pump impeller\u003c\/dd\u003e\n    \u003cdt\u003eProduct Configuration\u003c\/dt\u003e\n    \u003cdd\u003eSingle impeller\u003c\/dd\u003e\n    \u003cdt\u003eAftermarket Reference\u003c\/dt\u003e\n    \u003cdd\u003eSierra 18-8921\u003c\/dd\u003e\n    \u003cdt\u003ePrimary Manufacturer Reference\u003c\/dt\u003e\n    \u003cdd\u003eTohatsu 334-65021-0 \/ 334650210M\u003c\/dd\u003e\n    \u003cdt\u003eAdditional Manufacturer References\u003c\/dt\u003e\n    \u003cdd\u003eMercury 47-803748, 8M0135803, 8M0214944, 803748, 803748K01; Evinrude\/Johnson\/OMC\/BRP 5040046\u003c\/dd\u003e\n    \u003cdt\u003eApplication Range\u003c\/dt\u003e\n    \u003cdd\u003eSelected 2-stroke 9.9–18 HP and 4-stroke 9.9–20 HP outboards, subject to exact model and serial-number confirmation\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 aftermarket water pump impeller\u003c\/li\u003e\n  \u003c\/ul\u003e\n  \u003cp\u003e\u003cstrong\u003eImportant:\u003c\/strong\u003e The impeller key is not included with this single-impeller product. Reuse of an old key is not recommended if it is worn, damaged, or does not fit securely in the shaft keyway.\u003c\/p\u003e\n\n  \u003ch2\u003eInstallation Notes\u003c\/h2\u003e\n  \u003col\u003e\n    \u003cli\u003eDisconnect the battery and follow the outboard manufacturer’s service precautions.\u003c\/li\u003e\n    \u003cli\u003ePlace the engine in neutral and remove the lower unit according to the service manual for the specific model.\u003c\/li\u003e\n    \u003cli\u003eRemove the water pump housing and take note of the impeller, key, housing, and base-plate orientation.\u003c\/li\u003e\n    \u003cli\u003eRemove the old impeller and inspect the housing, wear plate, key, and driveshaft keyway for damage or excessive wear.\u003c\/li\u003e\n    \u003cli\u003eInstall the correct key for the engine, then align the replacement impeller with the keyway.\u003c\/li\u003e\n    \u003cli\u003eReinstall the water pump housing using the manufacturer’s specified blade orientation and assembly procedure.\u003c\/li\u003e\n    \u003cli\u003eReassemble the lower unit, restore the correct lubricant level, and test the cooling-water flow with an appropriate water supply.\u003c\/li\u003e\n    \u003cli\u003eStop the engine immediately if the tell-tale stream is weak or absent, or if an overheating warning occurs.\u003c\/li\u003e\n  \u003c\/ol\u003e\n\n  \u003ch2\u003eTroubleshooting \u0026amp; FAQ\u003c\/h2\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eHow do I confirm this impeller fits my engine?\u003c\/summary\u003e\n    \u003cp\u003eCompare your original impeller and manufacturer part number with the reference matrix, then confirm the complete engine brand, model, stroke type, horsepower, and serial-number range. Do not rely on horsepower alone.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eIs this a complete water pump kit?\u003c\/summary\u003e\n    \u003cp\u003eNo. This listing is for one water pump impeller only. It does not include an impeller key, water pump housing, wear plate, gasket, or other pump components.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eWhat are common signs of a worn impeller?\u003c\/summary\u003e\n    \u003cp\u003eA weak or missing tell-tale stream, overheating, or reduced cooling performance can indicate a worn, damaged, incorrectly installed, or obstructed water pump impeller. Inspect the complete cooling system before replacing parts.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eShould I replace the impeller key?\u003c\/summary\u003e\n    \u003cp\u003eInspect the key and keyway during service. Replace the key if it is worn, damaged, loose, or otherwise unsuitable. The correct key is not included with this single-impeller product.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eIs this an OEM part?\u003c\/summary\u003e\n    \u003cp\u003eNo. This is an aftermarket replacement impeller. The listed manufacturer and aftermarket numbers are reference numbers for identifying intended applications and compatibility.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eCan the same reference number fit both 2-stroke and 4-stroke engines?\u003c\/summary\u003e\n    \u003cp\u003eSome catalog references are listed across different engine families, but the complete model and serial-number conditions still determine fitment. Verify the application before installation.\u003c\/p\u003e\n  \u003c\/details\u003e\n\n  \u003ch2\u003eSafety \u0026amp; Important Information\u003c\/h2\u003e\n  \u003cul\u003e\n    \u003cli\u003eVerify the original part, reference number, dimensions, and engine application before ordering.\u003c\/li\u003e\n    \u003cli\u003eDo not operate an outboard with insufficient cooling-water flow.\u003c\/li\u003e\n    \u003cli\u003eFollow the manufacturer’s service manual for lower-unit removal, torque values, lubrication, and testing.\u003c\/li\u003e\n    \u003cli\u003eProfessional installation is recommended when the correct model, key, or installation procedure is uncertain.\u003c\/li\u003e\n    \u003cli\u003eThis is an aftermarket replacement and is not manufactured or endorsed by Mercury, Mariner, Tohatsu, Nissan, Evinrude, Johnson, OMC, BRP, or Sierra.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003ch2\u003eAbout Sea Sierra\u003c\/h2\u003e\n  \u003cul\u003e\n    \u003cli\u003e\n\u003cstrong\u003eMarine Replacement Parts\u003c\/strong\u003e — Practical aftermarket components for routine service and repair.\u003c\/li\u003e\n    \u003cli\u003e\n\u003cstrong\u003eApplication-Focused Listings\u003c\/strong\u003e — Reference numbers and model information are provided to help customers verify fitment.\u003c\/li\u003e\n    \u003cli\u003e\n\u003cstrong\u003eCustomer Support\u003c\/strong\u003e — Contact support with your engine model, horsepower, stroke type, serial number, and existing part number when compatibility is uncertain.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\u003c\/section\u003e","brand":"SeaSierra","offers":[{"title":"Default Title","offer_id":50723981984059,"sku":"17IT004","price":14.08,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0826\/8673\/8747\/files\/17IT0041_702bbbac-cf6d-488a-b538-5d75c62d8711.jpg?v=1763039288"}],"url":"https:\/\/seasierra.com\/collections\/tohatsu-4-stroke-7-5-10hp-outboard-engine-parts.oembed","provider":"SeaSierra","version":"1.0","type":"link"}