{"title":"Tohatsu 2-Stroke 3.5-40HP Outboard Marine Engine Parts","description":"\u003csection id=\"hero\" style=\"padding:16px 0;\"\u003e\n  \u003cp\u003eThis page focuses on Tohatsu 2‑Stroke 3.5–40HP outboard engines. Use it to find compatible replacement parts and service guidance. Below you’ll find maintenance tips, frequently used parts, and troubleshooting advice. You can also browse the main Tohatsu collection for a broader selection. Scroll to the bottom of the page to begin browsing parts for this engine, and remember that on the collection page you can use the “Filter \u0026amp; Sort” controls to narrow results by horsepower, year range, and part category.\u003c\/p\u003e\n  \u003cp\u003e\n    \u003ca href=\"https:\/\/seasierra.com\/collections\/tohatsu-outboard-parts\" style=\"display:inline-block;padding:10px 14px;border:1px solid #0a6f9a;border-radius:6px;text-decoration:none;\"\u003eBrowse All Tohatsu Parts\u003c\/a\u003e\n  \u003c\/p\u003e\n\u003c\/section\u003e\n\n\u003csection id=\"identify-model\" style=\"padding:12px 0;\"\u003e\n  \u003ch2\u003eHow to Identify Your 3.5–40HP Model\u003c\/h2\u003e\n  \u003cul\u003e\n    \u003cli\u003eLocate the identification plate on the transom\/clamp bracket or swivel bracket. It lists model, serial number, and specification suffixes.\u003c\/li\u003e\n    \u003cli\u003eRead the model code and suffix: suffix letters often indicate shaft length (S\/L\/XL), tiller vs. remote control, and electric start options.\u003c\/li\u003e\n    \u003cli\u003eFor 2‑stroke Tohatsu, portable models (3.5–9.8HP) are typically single‑ or twin‑cylinder; mid‑range (9.9–18HP) are twins; 25–30HP are twins, and 40HP is usually a 3‑cylinder platform.\u003c\/li\u003e\n    \u003cli\u003eCheck the serial number against the owner’s\/service manual to confirm year range and parts compatibility.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\u003c\/section\u003e\n\n\u003csection id=\"platforms\" style=\"padding:12px 0;\"\u003e\n  \u003ch2\u003ePlatform Overview\u003c\/h2\u003e\n\n  \u003ch3\u003ePortable 3.5–9.8HP 2‑Stroke\u003c\/h3\u003e\n  \u003ctable style=\"width:100%;max-width:920px;border-collapse:collapse;\"\u003e\n    \u003cthead\u003e\n      \u003ctr\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ddd;\"\u003eFeature\u003c\/th\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ddd;\"\u003eDescription\u003c\/th\u003e\n      \u003c\/tr\u003e\n    \u003c\/thead\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eConfiguration\u003c\/td\u003e\n        \u003ctd\u003eSingle‑ to twin‑cylinder, carbureted 2‑stroke, manual start on most models.\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eCommon Models\u003c\/td\u003e\n        \u003ctd\u003e3.5HP, 4HP, 5HP, 6HP, 8HP, 9.8HP two‑stroke variants.\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eAdvantages\u003c\/td\u003e\n        \u003ctd\u003eVery light, simple to maintain, ideal for dinghies and small boats.\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eNotes\u003c\/td\u003e\n        \u003ctd\u003eCarburetors and water pump kits vary by HP; confirm model code and shaft length before ordering.\u003c\/td\u003e\n      \u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\n  \u003ch3\u003eMid‑Range 9.9–18HP 2‑Stroke\u003c\/h3\u003e\n  \u003ctable style=\"width:100%;max-width:920px;border-collapse:collapse;margin-top:10px;\"\u003e\n    \u003cthead\u003e\n      \u003ctr\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ddd;\"\u003eFeature\u003c\/th\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ddd;\"\u003eDescription\u003c\/th\u003e\n      \u003c\/tr\u003e\n    \u003c\/thead\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eConfiguration\u003c\/td\u003e\n        \u003ctd\u003eTwin‑cylinder, carbureted 2‑stroke; tiller or remote variants.\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eCommon Models\u003c\/td\u003e\n        \u003ctd\u003e9.9HP, 15HP, 18HP two‑stroke outboards.\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eAdvantages\u003c\/td\u003e\n        \u003ctd\u003eStrong low‑end torque, straightforward service, widely supported parts.\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eNotes\u003c\/td\u003e\n        \u003ctd\u003eProp, carburetor jetting, and ignition details may differ by market\/year; match parts to your exact model code.\u003c\/td\u003e\n      \u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\n  \u003ch3\u003e25–30HP 2‑Stroke\u003c\/h3\u003e\n  \u003ctable style=\"width:100%;max-width:920px;border-collapse:collapse;margin-top:10px;\"\u003e\n    \u003cthead\u003e\n      \u003ctr\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ddd;\"\u003eFeature\u003c\/th\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ddd;\"\u003eDescription\u003c\/th\u003e\n      \u003c\/tr\u003e\n    \u003c\/thead\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eConfiguration\u003c\/td\u003e\n        \u003ctd\u003eTwin‑cylinder, carbureted 2‑stroke; electric start and remote options common.\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eCommon Models\u003c\/td\u003e\n        \u003ctd\u003e25HP and 30HP two‑stroke families with S\/L shaft options.\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eAdvantages\u003c\/td\u003e\n        \u003ctd\u003eGood power‑to‑weight, simple cooling and fueling systems.\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eNotes\u003c\/td\u003e\n        \u003ctd\u003eWater pump repair kits and fuel system parts are model‑year specific; verify by serial and suffix.\u003c\/td\u003e\n      \u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\n  \u003ch3\u003e40HP 2‑Stroke\u003c\/h3\u003e\n  \u003ctable style=\"width:100%;max-width:920px;border-collapse:collapse;margin-top:10px;\"\u003e\n    \u003cthead\u003e\n      \u003ctr\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ddd;\"\u003eFeature\u003c\/th\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ddd;\"\u003eDescription\u003c\/th\u003e\n      \u003c\/tr\u003e\n    \u003c\/thead\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eConfiguration\u003c\/td\u003e\n        \u003ctd\u003eInline‑3, carbureted 2‑stroke; remote control and electric start commonly fitted.\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eCommon Models\u003c\/td\u003e\n        \u003ctd\u003e40HP two‑stroke models in short\/long shaft variants.\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eAdvantages\u003c\/td\u003e\n        \u003ctd\u003eStrong mid‑range power, proven reliability.\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eNotes\u003c\/td\u003e\n        \u003ctd\u003eImpeller and thermostat specs differ from smaller platforms; confirm by model ID before purchase.\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\" style=\"padding:12px 0;\"\u003e\n  \u003ch2\u003eRoutine Maintenance \u0026amp; Service Parts\u003c\/h2\u003e\n  \u003cp\u003eIntervals below are general guidelines for 2‑stroke Tohatsu outboards. Always follow the procedures and schedules in your official service manual.\u003c\/p\u003e\n  \u003ctable style=\"width:100%;max-width:980px;border-collapse:collapse;\"\u003e\n    \u003cthead\u003e\n      \u003ctr\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ddd;\"\u003eItem\u003c\/th\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ddd;\"\u003eInterval*\u003c\/th\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ddd;\"\u003eRemarks\u003c\/th\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ddd;\"\u003eParts Link\u003c\/th\u003e\n      \u003c\/tr\u003e\n    \u003c\/thead\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eFuel\/oil mix or oil injection check\u003c\/td\u003e\n        \u003ctd\u003eEvery outing; inspect annually\u003c\/td\u003e\n        \u003ctd\u003ePremix engines typically run 50:1 TC‑W3; if oil‑injected, inspect pump\/lines and verify delivery.\u003c\/td\u003e\n        \u003ctd\u003e\u003ca href=\"https:\/\/seasierra.com\/collections\/service-maintenance-kits\"\u003eService \u0026amp; Maintenance Kits\u003c\/a\u003e\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eGear oil (lower unit)\u003c\/td\u003e\n        \u003ctd\u003e100 hours or annually\u003c\/td\u003e\n        \u003ctd\u003eCheck for water intrusion or metal; replace seals if milky oil is found.\u003c\/td\u003e\n        \u003ctd\u003e\u003ca href=\"https:\/\/seasierra.com\/collections\/tohatsu-lower-unit-seal-kits\"\u003eTohatsu Lower Unit Seal Kits\u003c\/a\u003e\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eSpark plugs\u003c\/td\u003e\n        \u003ctd\u003e100 hours or annually\u003c\/td\u003e\n        \u003ctd\u003eInspect gap\/condition; replace sooner if fouling or hard starts occur.\u003c\/td\u003e\n        \u003ctd\u003e\u003ca href=\"https:\/\/seasierra.com\/collections\/spark-plug\"\u003eSpark Plugs\u003c\/a\u003e\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eFuel filter \/ in‑line filter\u003c\/td\u003e\n        \u003ctd\u003e100 hours or annually\u003c\/td\u003e\n        \u003ctd\u003eReplace to prevent lean conditions and hard starting; drain water separators regularly.\u003c\/td\u003e\n        \u003ctd\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\u003eWater pump impeller \/ kit\u003c\/td\u003e\n        \u003ctd\u003eEvery 1–2 seasons (sooner in sandy\/silty water)\u003c\/td\u003e\n        \u003ctd\u003eWeak tell‑tale or overheat alarms often trace to a worn impeller or housing.\u003c\/td\u003e\n        \u003ctd\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\u003eThermostat\u003c\/td\u003e\n        \u003ctd\u003eInspect annually; replace ~2 years\u003c\/td\u003e\n        \u003ctd\u003eStuck thermostats affect warm‑up and can cause overheat or rich running.\u003c\/td\u003e\n        \u003ctd\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\u003eAnodes (internal\/externals)\u003c\/td\u003e\n        \u003ctd\u003eInspect each season; replace when 50% gone\u003c\/td\u003e\n        \u003ctd\u003eProtects against galvanic corrosion; monitor more often in salt\/brackish water.\u003c\/td\u003e\n        \u003ctd\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\u003c\/section\u003e\n\n\u003csection id=\"common-parts\" style=\"padding:12px 0;\"\u003e\n  \u003ch2\u003eFrequently Used Parts Categories\u003c\/h2\u003e\n  \u003cul\u003e\n    \u003cli\u003eAll Tohatsu Parts – \u003ca href=\"https:\/\/seasierra.com\/collections\/tohatsu-outboard-parts\"\u003eTohatsu Outboard Parts\u003c\/a\u003e\n\u003c\/li\u003e\n    \u003cli\u003eCooling System (Water Pump \u0026amp; Impeller) – \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\u003eFuel System (Pumps) – \u003ca href=\"https:\/\/seasierra.com\/collections\/fuel-pumps\"\u003eFuel Pumps\u003c\/a\u003e\n\u003c\/li\u003e\n    \u003cli\u003eFiltration (Fuel) – \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\n\u003c\/li\u003e\n    \u003cli\u003eGearcase Sealing – \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\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\" style=\"padding:12px 0;\"\u003e\n  \u003ch2\u003eCommon Symptoms \u0026amp; Quick Checks\u003c\/h2\u003e\n  \u003ctable style=\"width:100%;max-width:980px;border-collapse:collapse;\"\u003e\n    \u003cthead\u003e\n      \u003ctr\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ddd;\"\u003eSymptom\u003c\/th\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ddd;\"\u003eCheck First\u003c\/th\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ddd;\"\u003eRelated Parts\u003c\/th\u003e\n      \u003c\/tr\u003e\n    \u003c\/thead\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eWeak tell‑tale or overheat alarm\u003c\/td\u003e\n        \u003ctd\u003eInspect intake screen, impeller condition, thermostat operation.\u003c\/td\u003e\n        \u003ctd\u003eWater pump kit, impeller, thermostat, intake screen\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003ePoor acceleration or power loss\u003c\/td\u003e\n        \u003ctd\u003eCheck prop for damage\/fouling, verify fresh fuel, clean carburetor jets, confirm spark.\u003c\/td\u003e\n        \u003ctd\u003eCarburetor kit, fuel filter, spark plugs, propeller\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eHard starting \/ rough idle\u003c\/td\u003e\n        \u003ctd\u003eVerify choke\/enrichment, inspect spark plugs, test fuel pump and fuel lines for air leaks.\u003c\/td\u003e\n        \u003ctd\u003eSpark plugs, carburetor components, fuel pump, fuel line\/connector\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eExcessive smoke (2‑stroke)\u003c\/td\u003e\n        \u003ctd\u003eConfirm correct oil ratio or injection setting; check thermostat for proper warm‑up.\u003c\/td\u003e\n        \u003ctd\u003eSpark plugs, carburetor, thermostat\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eGearcase noise or metal in gear oil\u003c\/td\u003e\n        \u003ctd\u003eCheck oil level\/condition; look for water intrusion; inspect prop shaft seals.\u003c\/td\u003e\n        \u003ctd\u003eLower unit seal kit, bearings, gear oil\u003c\/td\u003e\n      \u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\u003c\/section\u003e\n\n\u003csection id=\"faq\" style=\"padding:12px 0;\"\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 overlap, but many parts—especially carburetors, ignition components, and cooling parts—are specific to the exact model code, suffix, and year range. Always confirm your model and serial before ordering.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eWhen should I replace the water pump impeller?\u003c\/summary\u003e\n    \u003cp\u003eAs a preventative measure, replace the impeller every 1–2 seasons (more often in sandy or silty conditions) or any time you notice a weak tell‑tale, overheating, or vane damage during inspection.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eHow often should I change lower unit gear oil?\u003c\/summary\u003e\n    \u003cp\u003eChange gear oil every 100 hours or annually. If water or metal is present, service seals and recheck after a short run.\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\u003eProvide the model code, serial number, shaft length (S\/L\/XL), control type (tiller\/remote), and any year\/market identifiers. A clear photo of the nameplate helps ensure an exact match.\u003c\/p\u003e\n  \u003c\/details\u003e\n\u003c\/section\u003e\n\n\u003csection id=\"cta\" style=\"padding:16px 0;\"\u003e\n  \u003cp\u003eReady to find the right parts? Browse the main Tohatsu collection by horsepower, year, and model to zero in on compatible components.\u003c\/p\u003e\n  \u003cp\u003e\n    \u003ca href=\"https:\/\/seasierra.com\/collections\/tohatsu-outboard-parts\" style=\"display:inline-block;padding:10px 14px;border:1px solid #0a6f9a;border-radius:6px;text-decoration:none;\"\u003eShop Tohatsu Outboard Parts\u003c\/a\u003e\n  \u003c\/p\u003e\n  \u003cp style=\"font-size:0.95em;color:#333;\"\u003eIf you’re unsure about your model, send us a clear photo of the engine’s nameplate and the part you need and we’ll help verify compatibility.\u003c\/p\u003e\n\u003c\/section\u003e","products":[{"product_id":"thermostat-fits-tohatsu-nissan-3-5hp-40hp-replaces-350-01030-346-01030-3h6-01030-0","title":"Thermostat for Nissan\/Tohatsu Marine Outboards 3.5–40 HP, 50°C – Replaces 350-01030-1, 345-01030-1, 346-01030","description":"\u003csection\u003e\n\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 { padding:10px 12px; border:1px solid #e5e7eb; text-align:left; vertical-align:top; }\n  table.ss-table th { white-space:nowrap; word-break:normal; letter-spacing:normal; font-weight:600; background:#f8fafc; }\n  @media (max-width:480px){ table.ss-table th, table.ss-table td { padding:8px 10px; font-size:14px; } }\n\u003c\/style\u003e\n\n\u003ch2\u003eProduct Details\u003c\/h2\u003e\n\u003cp\u003eThis aftermarket \u003cstrong\u003e50°C (122°F) thermostat\u003c\/strong\u003e is intended for selected Nissan and Tohatsu marine outboard applications. The company fitment range is listed as \u003cstrong\u003e3.5–40 HP\u003c\/strong\u003e, with specific small-engine references including 2, 2.5, 3.5, 4, 5, and 6 HP applications. Always match the thermostat specification and part number to your exact engine before ordering.\u003c\/p\u003e\n\u003cp\u003eThis thermostat is listed as a replacement for the following manufacturer references: \u003cstrong\u003e350-01030-1\u003c\/strong\u003e, \u003cstrong\u003e345-01030-1\u003c\/strong\u003e, \u003cstrong\u003e346-01030\u003c\/strong\u003e, and \u003cstrong\u003e346010320M\u003c\/strong\u003e. Additional catalog records identify \u003cstrong\u003e3H6-01030-0\u003c\/strong\u003e as a thermostat reference used on selected Tohatsu MFS 2–6 HP four-stroke models.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003e50°C (122°F) thermostat specification.\u003c\/li\u003e\n  \u003cli\u003eFor selected Nissan and Tohatsu marine outboard motors.\u003c\/li\u003e\n  \u003cli\u003eSuitable for applications across the company-listed 3.5–40 HP range, subject to exact model and part-number verification.\u003c\/li\u003e\n  \u003cli\u003eSold as one thermostat; gaskets, O-rings, seals, and other installation hardware are not confirmed as included unless shown in the product package received.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003ePart Number Matrix\u003c\/h2\u003e\n\u003cp\u003eUse the references below to compare your original thermostat and service-manual information. Part-number matching is recommended because horsepower ranges can overlap between different engine families.\u003c\/p\u003e\n\u003cdiv class=\"ss-table-wrap\"\u003e\n  \u003ctable class=\"ss-table\" aria-label=\"Part Number Matrix\"\u003e\n    \u003cthead\u003e\u003ctr\u003e\n\u003cth\u003eBrand or Reference\u003c\/th\u003e\n\u003cth\u003ePart Number\u003c\/th\u003e\n\u003c\/tr\u003e\u003c\/thead\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n\u003ctd\u003eTohatsu\u003c\/td\u003e\n\u003ctd\u003e350-01030-1\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eTohatsu\u003c\/td\u003e\n\u003ctd\u003e345-01030-1\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eTohatsu \/ Nissan\u003c\/td\u003e\n\u003ctd\u003e346-01030\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eCatalog reference\u003c\/td\u003e\n\u003ctd\u003e346010320M\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eSelected Tohatsu MFS applications\u003c\/td\u003e\n\u003ctd\u003e3H6-01030-0\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\u003eThe company lists this thermostat for Nissan and Tohatsu marine outboards from 3.5 to 40 HP and separately references 2, 2.5, 3.5, 4, 5, and 6 HP applications. The catalog examples below document selected applications for the listed manufacturer references; they are not a complete model-year or serial-number list.\u003c\/p\u003e\n\u003cdiv class=\"ss-table-wrap\"\u003e\n  \u003ctable class=\"ss-table\" aria-label=\"Engine and Model Compatibility\"\u003e\n    \u003cthead\u003e\u003ctr\u003e\n\u003cth\u003eBrand\u003c\/th\u003e\n\u003cth\u003eModel or Model Family\u003c\/th\u003e\n\u003cth\u003eRated HP\u003c\/th\u003e\n\u003cth\u003eStroke\u003c\/th\u003e\n\u003cth\u003eReference\u003c\/th\u003e\n\u003cth\u003eApplication Notes\u003c\/th\u003e\n\u003c\/tr\u003e\u003c\/thead\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n\u003ctd\u003eTohatsu\u003c\/td\u003e\n\u003ctd\u003eMFS2 \/ MFS2.5 \/ MFS3.5B\u003c\/td\u003e\n\u003ctd\u003e2–3.5\u003c\/td\u003e\n\u003ctd\u003e4-Stroke\u003c\/td\u003e\n\u003ctd\u003e3H6-01030-0\u003c\/td\u003e\n\u003ctd\u003eCatalog-listed applications for selected model years.\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eTohatsu\u003c\/td\u003e\n\u003ctd\u003eMFS4 \/ MFS5 \/ MFS6C\u003c\/td\u003e\n\u003ctd\u003e4–6\u003c\/td\u003e\n\u003ctd\u003e4-Stroke\u003c\/td\u003e\n\u003ctd\u003e3H6-01030-0\u003c\/td\u003e\n\u003ctd\u003eCatalog-listed applications for selected model years.\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eTohatsu\u003c\/td\u003e\n\u003ctd\u003eM6 \/ M8 \/ M9.8B\u003c\/td\u003e\n\u003ctd\u003e6–9.8\u003c\/td\u003e\n\u003ctd\u003e2-Stroke\u003c\/td\u003e\n\u003ctd\u003e350-01030-1\u003c\/td\u003e\n\u003ctd\u003eCatalog-listed applications for selected model years.\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eTohatsu\u003c\/td\u003e\n\u003ctd\u003eM9.9 \/ 15D2 \/ 18E2\u003c\/td\u003e\n\u003ctd\u003e9.9–18\u003c\/td\u003e\n\u003ctd\u003e2-Stroke\u003c\/td\u003e\n\u003ctd\u003e350-01030-1\u003c\/td\u003e\n\u003ctd\u003eCatalog-listed applications for selected model years.\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eTohatsu\u003c\/td\u003e\n\u003ctd\u003eMX15 \/ MX18E2\u003c\/td\u003e\n\u003ctd\u003e15–18\u003c\/td\u003e\n\u003ctd\u003e2-Stroke\u003c\/td\u003e\n\u003ctd\u003e350-01030-1\u003c\/td\u003e\n\u003ctd\u003eCatalog-listed applications for selected model years.\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eTohatsu\u003c\/td\u003e\n\u003ctd\u003eM25 \/ 30H \/ JET\u003c\/td\u003e\n\u003ctd\u003e25–30\u003c\/td\u003e\n\u003ctd\u003e2-Stroke\u003c\/td\u003e\n\u003ctd\u003e345-01030-1\u003c\/td\u003e\n\u003ctd\u003eCatalog-listed applications for 2025–2026 model records.\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eNissan \/ Tohatsu\u003c\/td\u003e\n\u003ctd\u003eSelected outboard models\u003c\/td\u003e\n\u003ctd\u003e3.5–40\u003c\/td\u003e\n\u003ctd\u003eNot specified\u003c\/td\u003e\n\u003ctd\u003e350-01030-1, 345-01030-1, 346-01030\u003c\/td\u003e\n\u003ctd\u003eVerify the exact model, year, serial range, and original thermostat reference.\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\u003c\/div\u003e\n\n\u003ch2\u003eTechnical Specifications\u003c\/h2\u003e\n\u003cdl\u003e\n  \u003cdt\u003eProduct Type\u003c\/dt\u003e\n  \u003cdd\u003eThermostat\u003c\/dd\u003e\n  \u003cdt\u003eTemperature Rating\u003c\/dt\u003e\n  \u003cdd\u003e50°C (122°F)\u003c\/dd\u003e\n  \u003cdt\u003eApplication\u003c\/dt\u003e\n  \u003cdd\u003eSelected Nissan and Tohatsu marine outboard motors\u003c\/dd\u003e\n  \u003cdt\u003eCompany-Listed Fitment Range\u003c\/dt\u003e\n  \u003cdd\u003e3.5–40 HP, with additional specific references to 2, 2.5, 3.5, 4, 5, and 6 HP applications\u003c\/dd\u003e\n  \u003cdt\u003eConstruction Material\u003c\/dt\u003e\n  \u003cdd\u003eNot specified by the company catalog\u003c\/dd\u003e\n  \u003cdt\u003eInstallation Hardware\u003c\/dt\u003e\n  \u003cdd\u003eNot specified; inspect the package contents before installation\u003c\/dd\u003e\n\u003c\/dl\u003e\n\n\u003ch2\u003eWhat’s in the Box\u003c\/h2\u003e\n\u003cul\u003e\n  \u003cli\u003e1 × Thermostat\u003c\/li\u003e\n  \u003cli\u003eGasket, O-rings, seals, and other hardware are not confirmed as included.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eInstallation Notes\u003c\/h2\u003e\n\u003col\u003e\n  \u003cli\u003eTurn off the outboard, remove the ignition key, and allow the engine to cool completely.\u003c\/li\u003e\n  \u003cli\u003eDisconnect the battery or follow the isolation procedure specified for your boat and engine.\u003c\/li\u003e\n  \u003cli\u003eLocate the thermostat housing using the engine service manual.\u003c\/li\u003e\n  \u003cli\u003eRemove the housing cover and note the original thermostat orientation before removal.\u003c\/li\u003e\n  \u003cli\u003eRemove the old thermostat and inspect the housing, mating surfaces, gasket, and sealing components.\u003c\/li\u003e\n  \u003cli\u003eClean the mating surfaces without damaging the housing or cylinder-head sealing area.\u003c\/li\u003e\n  \u003cli\u003eInstall the new thermostat in the correct orientation. Use a new gasket or seal only if required by the service manual and available for your application.\u003c\/li\u003e\n  \u003cli\u003eReinstall the housing cover and tighten the fasteners to the manufacturer’s specified torque.\u003c\/li\u003e\n  \u003cli\u003eRestore the cooling-water supply, start the engine, and check for leaks and proper water flow during a controlled test.\u003c\/li\u003e\n  \u003cli\u003eStop the engine immediately if it overheats, leaks, or shows abnormal temperature behavior.\u003c\/li\u003e\n\u003c\/ol\u003e\n\n\u003ch2\u003eTroubleshooting \u0026amp; FAQ\u003c\/h2\u003e\n\u003cdetails\u003e\n  \u003csummary\u003eWhat are the signs of a failing thermostat?\u003c\/summary\u003e\n  \u003cp\u003ePossible symptoms include overheating, unusually slow warm-up, unstable operating temperature, or temperature behavior that differs from the engine service-manual specification. Cooling-system blockages, water-pump problems, sensors, and incorrect installation can cause similar symptoms.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n  \u003csummary\u003eHow can I confirm this thermostat fits my engine?\u003c\/summary\u003e\n  \u003cp\u003eCompare the original thermostat and service-manual part number with the references listed above. Confirm the exact engine model, horsepower, stroke, model year, and serial-number range where applicable. Do not rely on horsepower alone.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n  \u003csummary\u003eIs this a 50°C or 60°C thermostat?\u003c\/summary\u003e\n  \u003cp\u003eThis listing is for a \u003cstrong\u003e50°C (122°F)\u003c\/strong\u003e thermostat. Use only the temperature rating specified for your engine.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n  \u003csummary\u003eIs this a complete repair kit?\u003c\/summary\u003e\n  \u003cp\u003eThe company record for this product identifies it as a single thermostat rather than a multi-component kit. Only one thermostat is confirmed. Gaskets, O-rings, and other service parts are not confirmed as included.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n  \u003csummary\u003eIs this an OEM part?\u003c\/summary\u003e\n  \u003cp\u003eThis is an aftermarket replacement, not an original manufacturer component. The manufacturer part numbers shown are provided for identification and compatibility reference only.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n  \u003csummary\u003eWhat should I do if my model is not listed?\u003c\/summary\u003e\n  \u003cp\u003eCheck the original thermostat number and your engine service manual. Contact support with the complete engine model, horsepower, stroke, year, and serial number before ordering if the application is unclear.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n  \u003csummary\u003eShipping speed and cost\u003c\/summary\u003e\n  \u003cp\u003eStandard shipping is free where offered. Typical transit is 5–15 days, while expedited options appear at checkout where available.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n  \u003csummary\u003eWarranty and returns\u003c\/summary\u003e\n  \u003cp\u003eThis product is covered by a 1-year warranty against manufacturing defects under normal use. Returns are accepted within the standard return window when the item is unused and in its original condition. Contact support for instructions.\u003c\/p\u003e\n\u003c\/details\u003e\n\n\u003ch2\u003eSafety \u0026amp; Important Information\u003c\/h2\u003e\n\u003cul\u003e\n  \u003cli\u003eVerify the exact engine application and thermostat temperature rating before purchase.\u003c\/li\u003e\n  \u003cli\u003eDo not assume that every engine within the listed horsepower range uses the same thermostat.\u003c\/li\u003e\n  \u003cli\u003eDo not operate the outboard without an adequate cooling-water supply.\u003c\/li\u003e\n  \u003cli\u003eAllow the engine to cool before servicing the thermostat housing.\u003c\/li\u003e\n  \u003cli\u003eThis is an aftermarket replacement, not an OEM component.\u003c\/li\u003e\n  \u003cli\u003eProfessional installation is recommended when the correct procedure or torque specification is unknown.\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 replacement parts selected for dependable service in real-world conditions.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eFast Global Fulfillment\u003c\/strong\u003e — Free standard delivery is available to most regions, with typical transit of 5–15 days.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eManufacturer-Direct Value\u003c\/strong\u003e — Fair pricing and practical marine-part support.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/section\u003e","brand":"SeaSierra","offers":[{"title":"Default Title","offer_id":50723963732283,"sku":"23TH616","price":26.4,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0826\/8673\/8747\/files\/23TH616_1_1f99fe24-5742-4094-b080-b914a992ae26.jpg?v=1763038510"}],"url":"https:\/\/seasierra.com\/collections\/tohatsu-2-stroke-3-5-40hp-outboard-marine-engine-parts.oembed","provider":"SeaSierra","version":"1.0","type":"link"}