{"product_id":"thermostat-fits-yamaha-75-90hp-4-stroke-replaces-6fp-12411-00-00-18-3641-775-240","title":"Thermostat – Fits Yamaha 75-90HP 4-Stroke (Replaces 6FP-12411-00-00, 18-3641, 775-240)","description":"\u003csection\u003e\n\u003c!-- 🔧 Table Styles (include only once per page) --\u003e\n\u003cstyle\u003e\n  \/* Outer container allows horizontal scrolling (with iOS momentum) *\/\n  .ss-table-wrap { overflow-x:auto; -webkit-overflow-scrolling:touch; }\n\n  \/* Base table styles *\/\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\n  \/* Key: prevent wrapping, word breaks, and vertical text in headers *\/\n  table.ss-table th {\n    white-space:nowrap;       \/* Do not wrap *\/\n    word-break:normal;        \/* Don’t break words *\/\n    letter-spacing:normal;    \/* Prevent theme styles from stretching letters *\/\n    font-weight:600;\n    background:#f8fafc;\n  }\n\n  \/* Small screen optimization *\/\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 replacement \u003cstrong\u003eThermostat – Fits Yamaha 75-90HP 4-Stroke Outboards\u003c\/strong\u003e is designed for select Yamaha F75B, F90B, and VF90A 4-cylinder outboard engines manufactured between 2016 and 2022. It ensures your engine maintains the correct operating temperature for optimal performance and longevity.\u003c\/p\u003e\n\u003cp\u003eThis component is a direct replacement for OEM part number 6FP-12411-00-00 and interchanges with Sierra 18-3641 and WSM 775-240.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eEngineered for direct-fit installation.\u003c\/li\u003e\n\u003cli\u003eRegulates engine temperature at 60°C (140°F).\u003c\/li\u003e\n\u003cli\u003eConstructed with a durable brass housing.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003ePart Number Matrix\u003c\/h2\u003e\n\u003cp\u003eUse this matrix to confirm equivalent references across OEM and aftermarket.\u003c\/p\u003e\n\u003cdiv class=\"ss-table-wrap\"\u003e\n  \u003ctable class=\"ss-table\" aria-label=\"Part Number Matrix\"\u003e\n    \u003cthead\u003e\n      \u003ctr\u003e\n        \u003cth\u003eBrand\u003c\/th\u003e\n        \u003cth\u003ePart Number\u003c\/th\u003e\n      \u003c\/tr\u003e\n    \u003c\/thead\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eYamaha\u003c\/td\u003e\n        \u003ctd\u003e6FP-12411-00-00\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eSierra\u003c\/td\u003e\n        \u003ctd\u003e18-3641\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eWSM\u003c\/td\u003e\n        \u003ctd\u003e775-240\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\u003eConfirm your engine model\/year in the table below.\u003c\/p\u003e\n\u003cdiv class=\"ss-table-wrap\"\u003e\n  \u003ctable class=\"ss-table\" aria-label=\"Engine \u0026amp; Model Compatibility\"\u003e\n    \u003cthead\u003e\n      \u003ctr\u003e\n        \u003cth\u003eBrand\u003c\/th\u003e\n        \u003cth\u003eModel\u003c\/th\u003e\n        \u003cth\u003eRated HP\u003c\/th\u003e\n        \u003cth\u003eStroke\u003c\/th\u003e\n        \u003cth\u003eYears\u003c\/th\u003e\n        \u003cth\u003eOEM Part No.\u003c\/th\u003e\n        \u003cth\u003eNotes\u003c\/th\u003e\n      \u003c\/tr\u003e\n    \u003c\/thead\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eYamaha\u003c\/td\u003e\n        \u003ctd\u003eF75B\u003c\/td\u003e\n        \u003ctd\u003e75\u003c\/td\u003e\n        \u003ctd\u003e4-Stroke\u003c\/td\u003e\n        \u003ctd\u003e2017–2022\u003c\/td\u003e\n        \u003ctd\u003e6FP-12411-00-00\u003c\/td\u003e\n        \u003ctd\u003e4-cylinder engine\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eYamaha\u003c\/td\u003e\n        \u003ctd\u003eF90B\u003c\/td\u003e\n        \u003ctd\u003e90\u003c\/td\u003e\n        \u003ctd\u003e4-Stroke\u003c\/td\u003e\n        \u003ctd\u003e2016–2022\u003c\/td\u003e\n        \u003ctd\u003e6FP-12411-00-00\u003c\/td\u003e\n        \u003ctd\u003e4-cylinder engine\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eYamaha\u003c\/td\u003e\n        \u003ctd\u003eVF90A Jet\u003c\/td\u003e\n        \u003ctd\u003e90\u003c\/td\u003e\n        \u003ctd\u003e4-Stroke\u003c\/td\u003e\n        \u003ctd\u003e2016–2022\u003c\/td\u003e\n        \u003ctd\u003e6FP-12411-00-00\u003c\/td\u003e\n        \u003ctd\u003e4-cylinder jet drive\u003c\/td\u003e\n      \u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\u003c\/div\u003e\n\n\u003ch2\u003eTechnical Specs\u003c\/h2\u003e\n\u003cdl\u003e\n  \u003cdt\u003eProduct Type\u003c\/dt\u003e\n\u003cdd\u003eOutboard Engine Thermostat\u003c\/dd\u003e\n  \u003cdt\u003eInstallation\u003c\/dt\u003e\n\u003cdd\u003eDirect replacement\u003c\/dd\u003e\n  \u003cdt\u003eOperating Temperature\u003c\/dt\u003e\n\u003cdd\u003e60°C (140°F)\u003c\/dd\u003e\n  \u003cdt\u003eHousing Material\u003c\/dt\u003e\n\u003cdd\u003eBrass\u003c\/dd\u003e\n  \u003cdt\u003eFitting Type\u003c\/dt\u003e\n\u003cdd\u003eDirect fit\u003c\/dd\u003e\n  \u003cdt\u003eCountry of Manufacture\u003c\/dt\u003e\n\u003cdd\u003eJapan (OEM); China (some aftermarket)\u003c\/dd\u003e\n  \u003cdt\u003eWarranty\u003c\/dt\u003e\n\u003cdd\u003eManufacturer-dependent\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 Thermostat (6FP-12411-00-00)\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eInstallation Notes\u003c\/h2\u003e\n\u003col\u003e\n\u003cli\u003eDisconnect the battery and ensure the engine is completely cool.\u003c\/li\u003e\n\u003cli\u003eLocate the thermostat housing on the engine block or cylinder head.\u003c\/li\u003e\n\u003cli\u003ePlace a drain pan underneath and remove the housing cover bolts, allowing any remaining coolant to drain.\u003c\/li\u003e\n\u003cli\u003eCarefully remove the old thermostat and gasket. Note the orientation of the thermostat.\u003c\/li\u003e\n\u003cli\u003eClean the mating surfaces of the housing and cover, removing all old gasket material.\u003c\/li\u003e\n\u003cli\u003eInstall the new thermostat in the correct orientation, followed by the new gasket.\u003c\/li\u003e\n\u003cli\u003eReattach the housing cover and tighten the bolts to the manufacturer's specified torque.\u003c\/li\u003e\n\u003cli\u003eRefill the cooling system with the recommended coolant, check for leaks, and reconnect the battery.\u003c\/li\u003e\n\u003c\/ol\u003e\n\n\u003ch2\u003eTroubleshooting \u0026amp; FAQ\u003c\/h2\u003e\n\u003cdetails\u003e\u003csummary\u003eHow do I know if my thermostat is failing?\u003c\/summary\u003e\u003cp\u003eCommon signs of a faulty thermostat include engine overheating, running too cool (not reaching operating temperature), erratic temperature gauge readings, and poor engine performance. Visually inspect for corrosion or a stuck-open\/closed valve.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eIs this thermostat compatible with my engine if it's not in the list?\u003c\/summary\u003e\u003cp\u003eNo. Only purchase this part if your specific engine model and year are explicitly listed in the compatibility table. Using the wrong thermostat can lead to severe engine damage.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eWhy is the operating temperature listed as 60°C while some sources say 62°C?\u003c\/summary\u003e\u003cp\u003eMinor variations in reported temperatures can occur between OEM and aftermarket sources. This thermostat is manufactured to operate at the standard 60°C (140°F) specification required for the listed Yamaha models, ensuring correct engine performance. Always defer to the OEM specification for your engine.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eWhat is the recommended replacement interval?\u003c\/summary\u003e\u003cp\u003eOutboard thermostats do not have a fixed replacement schedule, but they should be inspected during routine cooling system service (typically every 2-3 years or 200-300 hours). It is wise to replace it as a preventative measure if you are already servicing the water pump or cooling passages.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eCan I install this myself?\u003c\/summary\u003e\u003cp\u003eWhile installation can be done by a mechanically inclined owner, we recommend professional installation to ensure it is done correctly, torqued to spec, and the cooling system is properly bled. An improper installation can cause overheating and engine damage.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eOEM vs. Aftermarket?\u003c\/summary\u003e\u003cp\u003eThis listing is an aftermarket replacement (not OEM). Built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility, batch-inspected for consistency.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eShipping speed \u0026amp; cost\u003c\/summary\u003e\u003cp\u003eWe ship worldwide quickly—typical transit 5–15 days. Standard shipping is free; expedited options appear at checkout where available.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eWarranty \u0026amp; returns\u003c\/summary\u003e\u003cp\u003eCovered by a 1-year warranty against manufacturing defects under normal use. If issues arise, contact support with your order details. Returns are accepted within our standard window (unused T\u0026amp; in original condition). See our policy page or reach out for instructions.\u003c\/p\u003e\u003c\/details\u003e\n\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\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":50723983393083,"sku":"21TH015","price":45.5,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0826\/8673\/8747\/files\/Thermostat_for_Yamaha_75-90_HP_4-Stroke_16-UP_6FP-12411-00_6FP-12411-00-00_-_JLM_MARINE-8290922.jpg?v=1763039371","url":"https:\/\/seasierra.com\/products\/thermostat-fits-yamaha-75-90hp-4-stroke-replaces-6fp-12411-00-00-18-3641-775-240","provider":"SeaSierra","version":"1.0","type":"link"}