{"product_id":"thermostat-140-f-60-c-fits-yamaha-20-25hp-replaces-yamaha-6fm-12411-00-00-am6fm-12411-00","title":"Thermostat (140°F\/60°C) – Fits Yamaha 20-25HP (Replaces Yamaha 6FM-12411-00-00, AM6FM-12411-00)","description":"\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\u003csection\u003e\n    \u003ch2\u003eProduct Details\u003c\/h2\u003e\n    \u003cp\u003eThis replacement \u003cstrong\u003eThermostat (140°F\/60°C)\u003c\/strong\u003e is engineered to regulate engine temperature for select Yamaha 4-Stroke outboards. It is specifically compatible with 20HP (F20) models from 2018–2022 and 25HP (F25) models from 2016–2022, ensuring your engine maintains optimal performance and efficiency.\u003c\/p\u003e\n    \u003cp\u003eIt serves as a direct replacement for Yamaha OEM part 6FM-12411-00-00 and aftermarket equivalent AM6FM-12411-00.\u003c\/p\u003e\n    \u003cul\u003e\n        \u003cli\u003eInstalls as a direct OEM-equivalent replacement.\u003c\/li\u003e\n        \u003cli\u003eBuilt with corrosion-resistant metals for performance in both saltwater and freshwater.\u003c\/li\u003e\n        \u003cli\u003eIncludes one thermostat as shown in the package contents.\u003c\/li\u003e\n    \u003c\/ul\u003e\n\u003c\/section\u003e\n\u003csection\u003e\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\u003e6FM-12411-00-00\u003c\/td\u003e\n                \u003c\/tr\u003e\n                \u003ctr\u003e\n                    \u003ctd\u003eAftermarket\u003c\/td\u003e\n                    \u003ctd\u003eAM6FM-12411-00\u003c\/td\u003e\n                \u003c\/tr\u003e\n            \u003c\/tbody\u003e\n        \u003c\/table\u003e\n    \u003c\/div\u003e\n\u003c\/section\u003e\n\u003csection\u003e\n    \u003ch2\u003eEngine \u0026amp; Model Compatibility\u003c\/h2\u003e\n    \u003cp\u003eConfirm your engine model\/year in the table below.\u003c\/p\u003e\n    \u003cp\u003eThis thermostat is designed for the specified Yamaha 4-stroke outboard models.\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\u003eF20LMHB\u003c\/td\u003e\n\u003ctd\u003e20\u003c\/td\u003e\n\u003ctd\u003e4-Stroke\u003c\/td\u003e\n\u003ctd\u003e2018–2022\u003c\/td\u003e\n\u003ctd\u003e6FM-12411-00-00\u003c\/td\u003e\n\u003ctd\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n                \u003ctr\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003eF20LWB\u003c\/td\u003e\n\u003ctd\u003e20\u003c\/td\u003e\n\u003ctd\u003e4-Stroke\u003c\/td\u003e\n\u003ctd\u003e2018–2022\u003c\/td\u003e\n\u003ctd\u003e6FM-12411-00-00\u003c\/td\u003e\n\u003ctd\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n                \u003ctr\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003eF20LWHB\u003c\/td\u003e\n\u003ctd\u003e20\u003c\/td\u003e\n\u003ctd\u003e4-Stroke\u003c\/td\u003e\n\u003ctd\u003e2018–2022\u003c\/td\u003e\n\u003ctd\u003e6FM-12411-00-00\u003c\/td\u003e\n\u003ctd\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n                \u003ctr\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003eF20LWPB\u003c\/td\u003e\n\u003ctd\u003e20\u003c\/td\u003e\n\u003ctd\u003e4-Stroke\u003c\/td\u003e\n\u003ctd\u003e2018–2022\u003c\/td\u003e\n\u003ctd\u003e6FM-12411-00-00\u003c\/td\u003e\n\u003ctd\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n                \u003ctr\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003eF20LWPHB\u003c\/td\u003e\n\u003ctd\u003e20\u003c\/td\u003e\n\u003ctd\u003e4-Stroke\u003c\/td\u003e\n\u003ctd\u003e2018–2022\u003c\/td\u003e\n\u003ctd\u003e6FM-12411-00-00\u003c\/td\u003e\n\u003ctd\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n                \u003ctr\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003eF20SMHB\u003c\/td\u003e\n\u003ctd\u003e20\u003c\/td\u003e\n\u003ctd\u003e4-Stroke\u003c\/td\u003e\n\u003ctd\u003e2018–2022\u003c\/td\u003e\n\u003ctd\u003e6FM-12411-00-00\u003c\/td\u003e\n\u003ctd\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n                \u003ctr\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003eF20SWB\u003c\/td\u003e\n\u003ctd\u003e20\u003c\/td\u003e\n\u003ctd\u003e4-Stroke\u003c\/td\u003e\n\u003ctd\u003e2018–2022\u003c\/td\u003e\n\u003ctd\u003e6FM-12411-00-00\u003c\/td\u003e\n\u003ctd\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n                \u003ctr\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003eF20SWHB\u003c\/td\u003e\n\u003ctd\u003e20\u003c\/td\u003e\n\u003ctd\u003e4-Stroke\u003c\/td\u003e\n\u003ctd\u003e2018–2022\u003c\/td\u003e\n\u003ctd\u003e6FM-12411-00-00\u003c\/td\u003e\n\u003ctd\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n                \u003ctr\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003eF20SWPB\u003c\/td\u003e\n\u003ctd\u003e20\u003c\/td\u003e\n\u003ctd\u003e4-Stroke\u003c\/td\u003e\n\u003ctd\u003e2018–2022\u003c\/td\u003e\n\u003ctd\u003e6FM-12411-00-00\u003c\/td\u003e\n\u003ctd\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n                \u003ctr\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003eF25LC\u003c\/td\u003e\n\u003ctd\u003e25\u003c\/td\u003e\n\u003ctd\u003e4-Stroke\u003c\/td\u003e\n\u003ctd\u003e2016–2022\u003c\/td\u003e\n\u003ctd\u003e6FM-12411-00-00\u003c\/td\u003e\n\u003ctd\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n                \u003ctr\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003eF25LMHC\u003c\/td\u003e\n\u003ctd\u003e25\u003c\/td\u003e\n\u003ctd\u003e4-Stroke\u003c\/td\u003e\n\u003ctd\u003e2016–2022\u003c\/td\u003e\n\u003ctd\u003e6FM-12411-00-00\u003c\/td\u003e\n\u003ctd\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n                \u003ctr\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003eF25LWTC\u003c\/td\u003e\n\u003ctd\u003e25\u003c\/td\u003e\n\u003ctd\u003e4-Stroke\u003c\/td\u003e\n\u003ctd\u003e2017–2020\u003c\/td\u003e\n\u003ctd\u003e6FM-12411-00-00\u003c\/td\u003e\n\u003ctd\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n                \u003ctr\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003eF25LWC\u003c\/td\u003e\n\u003ctd\u003e25\u003c\/td\u003e\n\u003ctd\u003e4-Stroke\u003c\/td\u003e\n\u003ctd\u003e2016–2021\u003c\/td\u003e\n\u003ctd\u003e6FM-12411-00-00\u003c\/td\u003e\n\u003ctd\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n                \u003ctr\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003eF25LWHC\u003c\/td\u003e\n\u003ctd\u003e25\u003c\/td\u003e\n\u003ctd\u003e4-Stroke\u003c\/td\u003e\n\u003ctd\u003e2016–2021\u003c\/td\u003e\n\u003ctd\u003e6FM-12411-00-00\u003c\/td\u003e\n\u003ctd\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n                \u003ctr\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003eF25SMHC\u003c\/td\u003e\n\u003ctd\u003e25\u003c\/td\u003e\n\u003ctd\u003e4-Stroke\u003c\/td\u003e\n\u003ctd\u003e2016–2021\u003c\/td\u003e\n\u003ctd\u003e6FM-12411-00-00\u003c\/td\u003e\n\u003ctd\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n                \u003ctr\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003eF25SWC\u003c\/td\u003e\n\u003ctd\u003e25\u003c\/td\u003e\n\u003ctd\u003e4-Stroke\u003c\/td\u003e\n\u003ctd\u003e2016–2021\u003c\/td\u003e\n\u003ctd\u003e6FM-12411-00-00\u003c\/td\u003e\n\u003ctd\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n                \u003ctr\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003eF25SWHC\u003c\/td\u003e\n\u003ctd\u003e25\u003c\/td\u003e\n\u003ctd\u003e4-Stroke\u003c\/td\u003e\n\u003ctd\u003e2016–2021\u003c\/td\u003e\n\u003ctd\u003e6FM-12411-00-00\u003c\/td\u003e\n\u003ctd\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n                \u003ctr\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003eF25SC\u003c\/td\u003e\n\u003ctd\u003e25\u003c\/td\u003e\n\u003ctd\u003e4-Stroke\u003c\/td\u003e\n\u003ctd\u003e2022\u003c\/td\u003e\n\u003ctd\u003e6FM-12411-00-00\u003c\/td\u003e\n\u003ctd\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n                \u003ctr\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003eF25SWTC\u003c\/td\u003e\n\u003ctd\u003e25\u003c\/td\u003e\n\u003ctd\u003e4-Stroke\u003c\/td\u003e\n\u003ctd\u003e2022\u003c\/td\u003e\n\u003ctd\u003e6FM-12411-00-00\u003c\/td\u003e\n\u003ctd\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n                \u003ctr\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003eF25SWTHC\u003c\/td\u003e\n\u003ctd\u003e25\u003c\/td\u003e\n\u003ctd\u003e4-Stroke\u003c\/td\u003e\n\u003ctd\u003e2022\u003c\/td\u003e\n\u003ctd\u003e6FM-12411-00-00\u003c\/td\u003e\n\u003ctd\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n                \u003ctr\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003eT25LWTC\u003c\/td\u003e\n\u003ctd\u003e25\u003c\/td\u003e\n\u003ctd\u003e4-Stroke\u003c\/td\u003e\n\u003ctd\u003e2019–2021\u003c\/td\u003e\n\u003ctd\u003e6FM-12411-00-00\u003c\/td\u003e\n\u003ctd\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n                \u003ctr\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003eT25XWTC\u003c\/td\u003e\n\u003ctd\u003e25\u003c\/td\u003e\n\u003ctd\u003e4-Stroke\u003c\/td\u003e\n\u003ctd\u003e2019–2021\u003c\/td\u003e\n\u003ctd\u003e6FM-12411-00-00\u003c\/td\u003e\n\u003ctd\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n            \u003c\/tbody\u003e\n        \u003c\/table\u003e\n    \u003c\/div\u003e\n\u003c\/section\u003e\n\u003csection\u003e\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 OEM Replacement\u003c\/dd\u003e\n        \u003cdt\u003eHousing Material\u003c\/dt\u003e\n\u003cdd\u003eCorrosion-Resistant Metal\u003c\/dd\u003e\n        \u003cdt\u003eHousing Color\u003c\/dt\u003e\n\u003cdd\u003eBrass\/Metallic\u003c\/dd\u003e\n        \u003cdt\u003eFitting Type\u003c\/dt\u003e\n\u003cdd\u003eDirect Fit\u003c\/dd\u003e\n        \u003cdt\u003eOperating Temperature\u003c\/dt\u003e\n\u003cdd\u003e60°C (140°F)\u003c\/dd\u003e\n        \u003cdt\u003eOther Technical Attributes\u003c\/dt\u003e\n\u003cdd\u003eDesigned for both saltwater and freshwater environments\u003c\/dd\u003e\n    \u003c\/dl\u003e\n\u003c\/section\u003e\n\u003csection\u003e\n    \u003ch2\u003eWhat’s in the Box\u003c\/h2\u003e\n    \u003cul\u003e\n        \u003cli\u003e1 x Thermostat (6FM-12411-00-00)\u003c\/li\u003e\n    \u003c\/ul\u003e\n\u003c\/section\u003e\n\u003csection\u003e\n    \u003ch2\u003eInstallation Notes\u003c\/h2\u003e\n    \u003col\u003e\n        \u003cli\u003eEnsure the engine is off and cool. Disconnect the battery for safety.\u003c\/li\u003e\n        \u003cli\u003eLocate the thermostat housing on the cylinder head or block. Place a drain pan underneath if needed.\u003c\/li\u003e\n        \u003cli\u003eCarefully remove the bolts securing the housing cover. You may need to gently tap the cover to break the seal.\u003c\/li\u003e\n        \u003cli\u003eNote the orientation of the old thermostat before removing it and its gasket or seal.\u003c\/li\u003e\n        \u003cli\u003eThoroughly clean the mating surfaces of the housing and its 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\u003eRe-attach the housing cover and tighten the bolts evenly to the manufacturer's specified torque.\u003c\/li\u003e\n        \u003cli\u003eRefill the cooling system as needed and check for any leaks after starting the engine.\u003c\/li\u003e\n    \u003c\/ol\u003e\n\u003c\/section\u003e\n\u003csection\u003e\n    \u003ch2\u003eTroubleshooting \u0026amp; FAQ\u003c\/h2\u003e\n    \u003cdetails\u003e\n        \u003csummary\u003eWhat are the signs of a faulty outboard thermostat?\u003c\/summary\u003e\n        \u003cp\u003eCommon symptoms include the engine overheating at various speeds, an alarm sounding, or the engine failing to warm up to its proper operating temperature. An erratic temperature gauge reading can also indicate a problem.\u003c\/p\u003e\n    \u003c\/details\u003e\n    \u003cdetails\u003e\n        \u003csummary\u003eHow can I test if my current thermostat is working?\u003c\/summary\u003e\n        \u003cp\u003eYou can remove the thermostat and suspend it in a pot of water with a thermometer. Heat the water and observe the temperature at which the thermostat begins to open. This part should open at approximately 140°F (60°C). If it doesn't open or stays stuck open, it needs replacement.\u003c\/p\u003e\n    \u003c\/details\u003e\n    \u003cdetails\u003e\n        \u003csummary\u003eIs a gasket included with this thermostat?\u003c\/summary\u003e\n        \u003cp\u003eThis listing is for the thermostat only. Gaskets are typically sold separately. Always use a new gasket during installation to ensure a proper seal.\u003c\/p\u003e\n    \u003c\/details\u003e\n    \u003cdetails\u003e\n        \u003csummary\u003eWhy is a 140°F \/ 60°C temperature rating important?\u003c\/summary\u003e\n        \u003cp\u003eThis rating ensures the engine warms up quickly and maintains a consistent temperature for optimal fuel efficiency, performance, and reduced engine wear. Using the wrong temperature can lead to poor performance or damage.\u003c\/p\u003e\n    \u003c\/details\u003e\n    \u003cdetails\u003e\n        \u003csummary\u003eWhat is the difference between an OEM and an aftermarket part?\u003c\/summary\u003e\n        \u003cp\u003eThis listing is an aftermarket replacement (not OEM). It is built to OEM-level specifications with comparable materials. All our parts are manufactured in an ISO 9002 facility and are batch-inspected for quality and consistency.\u003c\/p\u003e\n    \u003c\/details\u003e\n    \u003cdetails\u003e\n        \u003csummary\u003eHow fast is shipping and what does it cost?\u003c\/summary\u003e\n        \u003cp\u003eWe ship worldwide quickly—typical transit is 5–15 days. Standard shipping is free to most regions, with expedited options available at checkout where applicable.\u003c\/p\u003e\n    \u003c\/details\u003e\n    \u003cdetails\u003e\n        \u003csummary\u003eWhat is the warranty and return policy?\u003c\/summary\u003e\n        \u003cp\u003eThis part is covered by a 1-year warranty against manufacturing defects under normal marine use. If you encounter an issue, please contact our support team with your order details. Returns are accepted within our standard window for unused items in their original condition. See our policy page or reach out for instructions.\u003c\/p\u003e\n    \u003c\/details\u003e\n\u003c\/section\u003e\n\u003csection\u003e\n    \u003ch2\u003eSafety \u0026amp; Important Info\u003c\/h2\u003e\n    \u003cul\u003e\n        \u003cli\u003eVerify images and specifications against your original part before ordering. If anything differs—even if your model appears in a compatibility list—do not purchase.\u003c\/li\u003e\n        \u003cli\u003eThis is an aftermarket replacement component, not an Original Equipment Manufacturer (OEM) part.\u003c\/li\u003e\n        \u003cli\u003eProfessional installation is recommended for safety and to ensure peak performance.\u003c\/li\u003e\n    \u003c\/ul\u003e\n\u003c\/section\u003e\n\u003csection\u003e\n    \u003ch2\u003eAbout Sea Sierra\u003c\/h2\u003e\n    \u003cul\u003e\n        \u003cli\u003e\n\u003cstrong\u003ePro-Grade Standards\u003c\/strong\u003e — We supply marine parts engineered to OEM-level tolerances and rigorously tested for real-world conditions.\u003c\/li\u003e\n        \u003cli\u003e\n\u003cstrong\u003eFast Global Fulfillment\u003c\/strong\u003e — We offer free standard delivery to most regions, with typical transit times of just 5–15 days.\u003c\/li\u003e\n        \u003cli\u003e\n\u003cstrong\u003eManufacturer-Direct Value\u003c\/strong\u003e — By working directly with manufacturers, we provide fair pricing without compromising on materials or quality control.\u003c\/li\u003e\n    \u003c\/ul\u003e\n\u003c\/section\u003e","brand":"SeaSierra","offers":[{"title":"Default Title","offer_id":50723797598523,"sku":"21TH027","price":41.39,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0826\/8673\/8747\/files\/21TH027_1_1b8303db-c946-463f-b1e6-b7fe28bde1d4.jpg?v=1763032024","url":"https:\/\/seasierra.com\/products\/thermostat-140-f-60-c-fits-yamaha-20-25hp-replaces-yamaha-6fm-12411-00-00-am6fm-12411-00","provider":"SeaSierra","version":"1.0","type":"link"}