{"title":"Tohatsu 4-Stroke 3-6HP Outboard Engine Parts","description":"\u003csection id=\"hero\" style=\"padding:16px 0;\"\u003e\n  \u003cp\u003e\n    This page is dedicated to Tohatsu 4‑Stroke 3–6HP outboard engines. Use it to find compatible parts and practical service information. Below you’ll find maintenance tips, common replacement parts, and troubleshooting guidance. You can also browse our main Tohatsu collection at any time. Scroll to the bottom of the page to start 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\/section.\n  \u003c\/p\u003e\n  \u003ca href=\"https:\/\/seasierra.com\/collections\/tohatsu-outboard-parts\" style=\"display:inline-block;padding:10px 16px;border:1px solid #0a5;border-radius:6px;text-decoration:none;\"\u003eBrowse All Tohatsu Parts\u003c\/a\u003e\n\u003c\/section\u003e\n\n\u003csection id=\"identify-model\"\u003e\n  \u003ch2\u003eHow to Identify Your 3–6HP Model\u003c\/h2\u003e\n  \u003cul\u003e\n    \u003cli\u003eLocate the nameplate\/serial label on the transom bracket or swivel bracket. It lists the model code, shaft length, and serial number.\u003c\/li\u003e\n    \u003cli\u003eModel codes typically begin with “MFS” for 4‑stroke models. The number indicates horsepower (e.g., 3.5, 4, 5, 6). Suffix letters often indicate shaft length (S\/L\/UL) and features.\u003c\/li\u003e\n    \u003cli\u003e3.5HP models are a distinct small single‑cylinder platform. The 4\/5\/6HP family shares many components (cooling and gearcase parts often interchange), but verify by exact model code and serial.\u003c\/li\u003e\n    \u003cli\u003eCheck tiller vs. remote features and charging options. These options can change the required electrical and control parts.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\u003c\/section\u003e\n\n\u003csection id=\"engine-overview\"\u003e\n  \u003ch2\u003ePlatform Overview\u003c\/h2\u003e\n  \u003ch3\u003e3.5HP 4‑Stroke Portable Platform\u003c\/h3\u003e\n  \u003ctable style=\"width:100%;max-width:900px;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‑cylinder 4‑stroke, carbureted; manual start; tiller steer; integral fuel tank on many versions.\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eCommon Models\u003c\/td\u003e\n        \u003ctd\u003eExamples often labeled similar to MFS3.5 variants (short\/long shaft).\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eAdvantages\u003c\/td\u003e\n        \u003ctd\u003eUltra‑lightweight, easy to carry, simple maintenance, quiet operation for its size.\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eNotes\u003c\/td\u003e\n        \u003ctd\u003eUses a smaller gearcase and distinct cooling parts versus the 4\/5\/6HP family—verify part fit by model and shaft length.\u003c\/td\u003e\n      \u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\n  \u003ch3\u003e4\/5\/6HP 4‑Stroke Portable Family\u003c\/h3\u003e\n  \u003ctable style=\"width:100%;max-width:900px;border-collapse:collapse;margin-top:12px;\"\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‑cylinder 4‑stroke, carbureted; manual start; tiller steer; optional external fuel connection on many models.\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eCommon Models\u003c\/td\u003e\n        \u003ctd\u003eExamples often labeled similar to MFS4, MFS5, and MFS6 variants (S\/L, optional charging).\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eAdvantages\u003c\/td\u003e\n        \u003ctd\u003eShared platform across 4\/5\/6HP for simpler parts sourcing, good fuel economy, low vibration for a portable class.\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eNotes\u003c\/td\u003e\n        \u003ctd\u003eMany water pump and gearcase parts interchange across 4\/5\/6HP. Prop pitch and diameter vary; verify with shaft length and application.\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 small 4‑stroke portable engines. Always follow your specific model’s service manual and local operating conditions.\u003c\/p\u003e\n  \u003ctable style=\"width:100%;max-width:1000px;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\u003eEngine oil\u003c\/td\u003e\n        \u003ctd\u003eFirst 20 hours, then every 100 hours or annually\u003c\/td\u003e\n        \u003ctd\u003eUse FC‑W marine oil (e.g., 10W‑30). Many 3–6HP models have no replaceable oil filter.\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\u003eGear oil (lower unit)\u003c\/td\u003e\n        \u003ctd\u003eEvery 100 hours or annually\u003c\/td\u003e\n        \u003ctd\u003eInspect for water intrusion (milky oil). Replace seals if contamination 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\u003eInspect every 100 hours; replace ~200 hours or as needed\u003c\/td\u003e\n        \u003ctd\u003eCheck gap and replace if fouled, worn, or corroded.\u003c\/td\u003e\n        \u003ctd\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\u003eFuel filter \/ inline filter\u003c\/td\u003e\n        \u003ctd\u003eInspect every 100 hours; replace as needed\u003c\/td\u003e\n        \u003ctd\u003eReplace sooner for stale fuel, debris, or storage‑related varnish.\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 2–3 seasons (sooner in sandy\/silty water)\u003c\/td\u003e\n        \u003ctd\u003eWeak tell‑tale or overheat alarm suggests service is due.\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\u003eAnodes (sacrificial)\u003c\/td\u003e\n        \u003ctd\u003eInspect every 50 hours; replace when 50% consumed\u003c\/td\u003e\n        \u003ctd\u003eUse correct alloy for your waters (fresh, brackish, or salt).\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      \u003ctr\u003e\n        \u003ctd\u003ePropeller \u0026amp; cotter pin\u003c\/td\u003e\n        \u003ctd\u003eInspect every trip\/season\u003c\/td\u003e\n        \u003ctd\u003eRemove fishing line and check for dings; verify thrust washer orientation.\u003c\/td\u003e\n        \u003ctd\u003e\u003ca href=\"https:\/\/seasierra.com\/collections\/propellers\"\u003ePropellers\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\"\u003e\n  \u003ch2\u003eFrequently Used Parts Categories\u003c\/h2\u003e\n  \u003cul\u003e\n    \u003cli\u003eRoutine Service: \u003ca href=\"https:\/\/seasierra.com\/collections\/tohatsu-outboard-parts\"\u003eTohatsu Outboard Parts\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\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\n\u003c\/li\u003e\n    \u003cli\u003eGearcase 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 \u0026amp; Hardware: \u003ca href=\"https:\/\/seasierra.com\/collections\/propellers\"\u003ePropellers\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%;max-width:1000px;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 for blockage; verify impeller condition; confirm thermostat function.\u003c\/td\u003e\n        \u003ctd\u003eWater pump kit, intake screen, thermostat, gaskets\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eHard starting or rough idle\u003c\/td\u003e\n        \u003ctd\u003eConfirm fresh fuel and open tank vent; check spark plug gap; clean\/adjust carburetor idle circuit.\u003c\/td\u003e\n        \u003ctd\u003eSpark plugs, fuel filter, carburetor repair kit\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003ePoor acceleration or power loss\u003c\/td\u003e\n        \u003ctd\u003eCheck propeller for damage\/cavitation; inspect fuel filter and lines; confirm choke\/enrichment operation.\u003c\/td\u003e\n        \u003ctd\u003ePropeller, fuel filter, fuel hose\/connector, carburetor jets\/kit\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eGearcase noise or metal in gear oil\u003c\/td\u003e\n        \u003ctd\u003eVerify oil level and condition; inspect seals for leaks; ensure correct thrust washer and prop fitment.\u003c\/td\u003e\n        \u003ctd\u003eLower unit seal kit, gear oil, prop hardware\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eFuel starvation with built‑in tank\u003c\/td\u003e\n        \u003ctd\u003eMake sure cap vent is open; inspect O‑rings; check for debris in pickup and inline filter.\u003c\/td\u003e\n        \u003ctd\u003eFuel cap O‑rings, inline filter, fuel connector\/hose\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 3.5HP and 4\/5\/6HP models?\u003c\/summary\u003e\n    \u003cp\u003eOnly some items interchange. The 4\/5\/6HP family shares many cooling and gearcase parts, but 3.5HP uses a distinct platform. Confirm by model code, shaft length, and serial number before ordering.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eWhen should I replace the impeller?\u003c\/summary\u003e\n    \u003cp\u003eAs a rule of thumb, every 2–3 seasons in normal use, or immediately if you see a weak tell‑tale, overheat warnings, or if the engine was run dry or in sandy water.\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 at least annually or every 100 hours. If the drained oil looks milky or shows metal, service the seals and recheck after the next outing.\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 (e.g., MFS5 with suffix for shaft length\/features), serial number, and a clear photo of the nameplate. Noting shaft length (S\/L\/UL) and any charging\/remote options also helps.\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 parts by horsepower, year, and model? Browse our main Tohatsu collection for the best match to your 3–6HP engine.\u003c\/p\u003e\n  \u003ca href=\"https:\/\/seasierra.com\/collections\/tohatsu-outboard-parts\" style=\"display:inline-block;padding:10px 16px;border:1px solid #0a5;border-radius:6px;text-decoration:none;\"\u003eShop Tohatsu Outboard Parts\u003c\/a\u003e\n  \u003cp style=\"font-size:0.95em;color:#444;margin-top:8px;\"\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":"thermostat-fits-tohatsu-mercury-evinrude-2-6-hp-4-stroke-replaces-3h6-01030-0-804540","title":"Outboard Thermostat for Mercury\/Mariner, Tohatsu\/Nissan \u0026 Evinrude\/Johnson – 50°C (122°F)","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 {\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 aftermarket outboard thermostat is designed for selected Mercury\/Mariner, Tohatsu\/Nissan, and Evinrude\/Johnson marine engines. It helps regulate engine temperature at the specified \u003cstrong\u003e50°C (122°F)\u003c\/strong\u003e operating point for the compatible applications listed below.\u003c\/p\u003e\n\u003cp\u003eThe thermostat is sold as a \u003cstrong\u003esingle replacement component\u003c\/strong\u003e. It is listed for applications using Mercury references \u003cstrong\u003e804540\u003c\/strong\u003e and \u003cstrong\u003e853704\u003c\/strong\u003e, Tohatsu references \u003cstrong\u003e3H6-01030-0\u003c\/strong\u003e and \u003cstrong\u003e345-01030-0\u003c\/strong\u003e, Evinrude\/Johnson reference \u003cstrong\u003e5040958\u003c\/strong\u003e, and Sierra reference \u003cstrong\u003e18-3638\u003c\/strong\u003e.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eReplacement thermostat for selected outboard cooling systems.\u003c\/li\u003e\n  \u003cli\u003eTemperature specification: 50°C (122°F).\u003c\/li\u003e\n  \u003cli\u003eOne thermostat included.\u003c\/li\u003e\n  \u003cli\u003eConfirm the complete engine model, horsepower, stroke, and serial-number range before ordering.\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 identification and cross-reference purposes. Always compare the original part and engine application before installation.\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\u003c\/th\u003e\n\u003cth\u003eReference\u003c\/th\u003e\n\u003c\/tr\u003e\u003c\/thead\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n\u003ctd\u003eMercury\u003c\/td\u003e\n\u003ctd\u003e804540\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eMercury\u003c\/td\u003e\n\u003ctd\u003e853704\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eTohatsu\/Nissan\u003c\/td\u003e\n\u003ctd\u003e3H6-01030-0\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eTohatsu\/Nissan\u003c\/td\u003e\n\u003ctd\u003e345-01030-0\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eTohatsu\/Nissan\u003c\/td\u003e\n\u003ctd\u003e3H6010300 \/ 3H6010300M\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eEvinrude\/Johnson\u003c\/td\u003e\n\u003ctd\u003e5040958\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eSierra\u003c\/td\u003e\n\u003ctd\u003e18-3638\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\u003c\/div\u003e\n\n\u003ch2\u003eEngine Compatibility\u003c\/h2\u003e\n\u003cp\u003eCompany fitment information identifies the following application groups. Model, stroke, and serial-number conditions must remain together when checking compatibility; horsepower alone is not sufficient.\u003c\/p\u003e\n\u003cdiv class=\"ss-table-wrap\"\u003e\n  \u003ctable class=\"ss-table\" aria-label=\"Mercury and Mariner Compatibility\"\u003e\n    \u003cthead\u003e\u003ctr\u003e\n\u003cth\u003eBrand\u003c\/th\u003e\n\u003cth\u003eApplication\u003c\/th\u003e\n\u003cth\u003eHorsepower\u003c\/th\u003e\n\u003cth\u003eStroke \/ Configuration\u003c\/th\u003e\n\u003cth\u003eSerial Condition\u003c\/th\u003e\n\u003cth\u003eReference\u003c\/th\u003e\n\u003c\/tr\u003e\u003c\/thead\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n\u003ctd\u003eMercury\/Mariner\u003c\/td\u003e\n\u003ctd\u003eSelected carbureted models\u003c\/td\u003e\n\u003ctd\u003e2.5–3.5 HP\u003c\/td\u003e\n\u003ctd\u003e4-Stroke\u003c\/td\u003e\n\u003ctd\u003e0R131842 and up\u003c\/td\u003e\n\u003ctd\u003e804540\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eMercury\/Mariner\u003c\/td\u003e\n\u003ctd\u003eSelected models\u003c\/td\u003e\n\u003ctd\u003e4–6 HP\u003c\/td\u003e\n\u003ctd\u003e4-Stroke\u003c\/td\u003e\n\u003ctd\u003e0R411838 and up\u003c\/td\u003e\n\u003ctd\u003e804540\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eMercury\/Mariner International\u003c\/td\u003e\n\u003ctd\u003eTwo-cylinder, 430 cc applications\u003c\/td\u003e\n\u003ctd\u003e25–30 HP\u003c\/td\u003e\n\u003ctd\u003eConfirm the engine model and stroke\u003c\/td\u003e\n\u003ctd\u003eConfirm the engine serial number\u003c\/td\u003e\n\u003ctd\u003e804540 \/ 853704\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=\"Tohatsu and Nissan Compatibility\"\u003e\n    \u003cthead\u003e\u003ctr\u003e\n\u003cth\u003eBrand\u003c\/th\u003e\n\u003cth\u003eApplication Range\u003c\/th\u003e\n\u003cth\u003eHorsepower\u003c\/th\u003e\n\u003cth\u003eReference\u003c\/th\u003e\n\u003cth\u003eNotes\u003c\/th\u003e\n\u003c\/tr\u003e\u003c\/thead\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n\u003ctd\u003eTohatsu\/Nissan\u003c\/td\u003e\n\u003ctd\u003eSelected marine outboard applications\u003c\/td\u003e\n\u003ctd\u003e3.5–40 HP\u003c\/td\u003e\n\u003ctd\u003e3H6-01030-0 \/ 345-01030-0\u003c\/td\u003e\n\u003ctd\u003eVerify 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=\"Evinrude and Johnson Compatibility\"\u003e\n    \u003cthead\u003e\u003ctr\u003e\n\u003cth\u003eBrand\u003c\/th\u003e\n\u003cth\u003eApplication\u003c\/th\u003e\n\u003cth\u003eHorsepower\u003c\/th\u003e\n\u003cth\u003eReference\u003c\/th\u003e\n\u003cth\u003eNotes\u003c\/th\u003e\n\u003c\/tr\u003e\u003c\/thead\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n\u003ctd\u003eEvinrude\/Johnson\u003c\/td\u003e\n\u003ctd\u003eSelected outboard applications\u003c\/td\u003e\n\u003ctd\u003e3, 4, and 6 HP\u003c\/td\u003e\n\u003ctd\u003e5040958\u003c\/td\u003e\n\u003ctd\u003eVerify the exact model, year, 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 Specifications\u003c\/h2\u003e\n\u003cdl\u003e\n  \u003cdt\u003eProduct Type\u003c\/dt\u003e\n  \u003cdd\u003eOutboard engine thermostat\u003c\/dd\u003e\n  \u003cdt\u003eTemperature Specification\u003c\/dt\u003e\n  \u003cdd\u003e50°C (122°F)\u003c\/dd\u003e\n  \u003cdt\u003eInstallation Location\u003c\/dt\u003e\n  \u003cdd\u003eEngine cooling system \/ thermostat housing\u003c\/dd\u003e\n  \u003cdt\u003eProduct Format\u003c\/dt\u003e\n  \u003cdd\u003eSingle replacement component\u003c\/dd\u003e\n  \u003cdt\u003eReplacement References\u003c\/dt\u003e\n  \u003cdd\u003eMercury 804540 and 853704; Tohatsu\/Nissan 3H6-01030-0 and 345-01030-0; Evinrude\/Johnson 5040958; Sierra 18-3638\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 Outboard thermostat\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eA gasket, seal, or additional installation hardware is not specified as included. Reuse only components that are confirmed serviceable, or obtain replacement sealing parts separately when required by the engine service procedure.\u003c\/p\u003e\n\n\u003ch2\u003eInstallation Notes\u003c\/h2\u003e\n\u003col\u003e\n  \u003cli\u003eAllow the engine to cool completely before beginning work.\u003c\/li\u003e\n  \u003cli\u003ePrevent accidental starting and follow the safety instructions in the engine service manual.\u003c\/li\u003e\n  \u003cli\u003eLocate the thermostat housing and confirm that the replacement part matches the original component.\u003c\/li\u003e\n  \u003cli\u003eRemove the housing cover according to the manufacturer's procedure.\u003c\/li\u003e\n  \u003cli\u003eRemove the old thermostat and inspect the housing, sealing surfaces, and related components for damage or deposits.\u003c\/li\u003e\n  \u003cli\u003eInstall the replacement thermostat in the same orientation as the original part.\u003c\/li\u003e\n  \u003cli\u003eInstall a suitable new gasket or seal if required by the engine service manual. No gasket is specified as included with this product.\u003c\/li\u003e\n  \u003cli\u003eReinstall the housing cover and tighten fasteners to the manufacturer's specified torque.\u003c\/li\u003e\n  \u003cli\u003eRun the engine using the correct test procedure and check for leaks and proper cooling-system operation.\u003c\/li\u003e\n\u003c\/ol\u003e\n\n\u003ch2\u003eTroubleshooting \u0026amp; FAQ\u003c\/h2\u003e\n\u003cdetails\u003e\n  \u003csummary\u003eWhat temperature is this thermostat specified for?\u003c\/summary\u003e\n  \u003cp\u003eThe company specification is \u003cstrong\u003e50°C (122°F)\u003c\/strong\u003e. This is the listed temperature specification for the compatible applications.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n  \u003csummary\u003eHow do I confirm that it fits my engine?\u003c\/summary\u003e\n  \u003cp\u003eCompare your original thermostat reference with the Part Number Matrix, then verify the engine brand, exact model, horsepower, stroke or configuration, year where applicable, and serial-number range. For Mercury\/Mariner applications, the listed serial conditions include 0R131842 and up for selected 2.5–3.5 HP 4-stroke models and 0R411838 and up for selected 4–6 HP 4-stroke models.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n  \u003csummary\u003eDoes this listing include a gasket or housing?\u003c\/summary\u003e\n  \u003cp\u003eNo. The package contains one thermostat only. A gasket, seal, housing, or other installation hardware is not specified as included.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n  \u003csummary\u003eWhat are common symptoms of a thermostat problem?\u003c\/summary\u003e\n  \u003cp\u003ePossible symptoms include overheating, abnormal operating temperature, or an engine that runs cooler than expected. Cooling-system problems can have several causes, so inspect water flow, passages, seals, and related components before replacing the thermostat.\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 component. The manufacturer references shown above are provided for identification and compatibility cross-reference only; this product is not represented as a genuine OEM component.\u003c\/p\u003e\n\u003c\/details\u003e\n\n\u003ch2\u003eSafety \u0026amp; Important Information\u003c\/h2\u003e\n\u003cul\u003e\n  \u003cli\u003eDo not rely on horsepower alone to determine fitment.\u003c\/li\u003e\n  \u003cli\u003eVerify the exact engine model, stroke or configuration, year where applicable, and serial number before ordering.\u003c\/li\u003e\n  \u003cli\u003eCompare the replacement part with the original thermostat and inspect all sealing surfaces before installation.\u003c\/li\u003e\n  \u003cli\u003eUse the engine manufacturer's service procedure and specified torque values.\u003c\/li\u003e\n  \u003cli\u003eProfessional installation is recommended when the correct procedure or application is uncertain.\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 replacement components for selected marine engine applications.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eApplication-Focused Listings\u003c\/strong\u003e — Reference numbers and fitment conditions are provided to support accurate part selection.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eSupport for Maintenance Work\u003c\/strong\u003e — Confirm your engine details and original part before ordering or installing.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003c\/section\u003e","brand":"SeaSierra","offers":[{"title":"Default Title","offer_id":50723807920443,"sku":"23TH619","price":31.9,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0826\/8673\/8747\/files\/Thermostat_for_Tohatsu_Mercury_2-6_hp_4-St_3H6-01030-0_804540___345-01030-0_3H6-01030-0_-_JLM_MARINE-8291185.jpg?v=1763032298"}],"url":"https:\/\/seasierra.com\/collections\/tohatsu-4-stroke-3-6hp-outboard-engine-parts.oembed","provider":"SeaSierra","version":"1.0","type":"link"}