{"product_id":"thermostat-kit-fits-johnson-evinrude-v4-crossflow-65-140-hp-replaces-18-3673-340975-340976","title":"Thermostat Kit – Fits Johnson\/Evinrude V4 Crossflow 65-140 HP (Replaces 18-3673, 340975, 340976)","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 complete \u003cstrong\u003eThermostat Kit – Fits Johnson\/Evinrude V4 Crossflow 65–140 HP\u003c\/strong\u003e outboards is a crucial component for maintaining optimal engine temperature. It is specifically designed for 2-stroke V4 Crossflow models manufactured between 1978 and 1995, providing a reliable cooling system overhaul for various engines, including 65, 80, and 90 Jet models and commercial applications.\u003c\/p\u003e\n\u003cp\u003eIt serves as a direct interchange for a wide range of part numbers, including Johnson\/Evinrude \u0026amp; Sierra 18-3673, GLM 13270, and OMC numbers 340975, 340976, 393659, 434841, 378065, 508626, and 5005440.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eInstalls as a direct OEM-style replacement with factory-fit connections.\u003c\/li\u003e\n\u003cli\u003eMaintains correct engine operating temperature with thermostats rated at 143°F (62°C).\u003c\/li\u003e\n\u003cli\u003eIncludes all necessary components for a dual thermostat system, including starboard and port hoses.\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\u003eSierra\u003c\/td\u003e\n\u003ctd\u003e18-3673\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eJohnson\/Evinrude\u003c\/td\u003e\n\u003ctd\u003e18-3673\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eGLM\u003c\/td\u003e\n\u003ctd\u003e13270\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eOMC\u003c\/td\u003e\n\u003ctd\u003e340975\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eOMC\u003c\/td\u003e\n\u003ctd\u003e340976\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eOMC\u003c\/td\u003e\n\u003ctd\u003e393659\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eOMC\u003c\/td\u003e\n\u003ctd\u003e434841\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eOMC\u003c\/td\u003e\n\u003ctd\u003e378065\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eOMC\u003c\/td\u003e\n\u003ctd\u003e508626\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eOMC\u003c\/td\u003e\n\u003ctd\u003e5005440\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\u003cp\u003eThis kit is designed for the following Johnson\/Evinrude V4 Crossflow outboard engines:\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      \u003c\/tr\u003e\n    \u003c\/thead\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n\u003ctd\u003eJohnson\/Evinrude\u003c\/td\u003e\n\u003ctd\u003eV4 Crossflow\u003c\/td\u003e\n\u003ctd\u003e65 Jet\u003c\/td\u003e\n\u003ctd\u003e2-Stroke\u003c\/td\u003e\n\u003ctd\u003e1994–1995\u003c\/td\u003e\n\u003ctd\u003e340975, 340976, 18-3673\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eJohnson\/Evinrude\u003c\/td\u003e\n\u003ctd\u003eV4 Crossflow\u003c\/td\u003e\n\u003ctd\u003e80 Jet\u003c\/td\u003e\n\u003ctd\u003e2-Stroke\u003c\/td\u003e\n\u003ctd\u003e1994–1995\u003c\/td\u003e\n\u003ctd\u003e340975, 340976, 18-3673\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eJohnson\/Evinrude\u003c\/td\u003e\n\u003ctd\u003eV4 Crossflow\u003c\/td\u003e\n\u003ctd\u003e90 Jet\u003c\/td\u003e\n\u003ctd\u003e2-Stroke\u003c\/td\u003e\n\u003ctd\u003e1994\u003c\/td\u003e\n\u003ctd\u003e340975, 340976, 18-3673\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eJohnson\/Evinrude\u003c\/td\u003e\n\u003ctd\u003eV4 Crossflow\u003c\/td\u003e\n\u003ctd\u003e85\u003c\/td\u003e\n\u003ctd\u003e2-Stroke\u003c\/td\u003e\n\u003ctd\u003e1978–1980, 1993–1995\u003c\/td\u003e\n\u003ctd\u003e340975, 340976, 18-3673\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eJohnson\/Evinrude\u003c\/td\u003e\n\u003ctd\u003eV4 Crossflow\u003c\/td\u003e\n\u003ctd\u003e88\u003c\/td\u003e\n\u003ctd\u003e2-Stroke\u003c\/td\u003e\n\u003ctd\u003e1984–1995\u003c\/td\u003e\n\u003ctd\u003e340975, 340976, 18-3673\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eJohnson\/Evinrude\u003c\/td\u003e\n\u003ctd\u003eV4 Crossflow\u003c\/td\u003e\n\u003ctd\u003e90\u003c\/td\u003e\n\u003ctd\u003e2-Stroke\u003c\/td\u003e\n\u003ctd\u003e1983–1995\u003c\/td\u003e\n\u003ctd\u003e340975, 340976, 18-3673\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eJohnson\/Evinrude\u003c\/td\u003e\n\u003ctd\u003eV4 Crossflow\u003c\/td\u003e\n\u003ctd\u003e100\u003c\/td\u003e\n\u003ctd\u003e2-Stroke\u003c\/td\u003e\n\u003ctd\u003e1979–1980, 1990–1995\u003c\/td\u003e\n\u003ctd\u003e340975, 340976, 18-3673\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eJohnson\/Evinrude\u003c\/td\u003e\n\u003ctd\u003eV4 Crossflow\u003c\/td\u003e\n\u003ctd\u003e100 Commercial\u003c\/td\u003e\n\u003ctd\u003e2-Stroke\u003c\/td\u003e\n\u003ctd\u003e1984–1989\u003c\/td\u003e\n\u003ctd\u003e340975, 340976, 18-3673\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eJohnson\/Evinrude\u003c\/td\u003e\n\u003ctd\u003eV4 Crossflow\u003c\/td\u003e\n\u003ctd\u003e110\u003c\/td\u003e\n\u003ctd\u003e2-Stroke\u003c\/td\u003e\n\u003ctd\u003e1985–1989\u003c\/td\u003e\n\u003ctd\u003e340975, 340976, 18-3673\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eJohnson\/Evinrude\u003c\/td\u003e\n\u003ctd\u003eV4 Crossflow\u003c\/td\u003e\n\u003ctd\u003e112\u003c\/td\u003e\n\u003ctd\u003e2-Stroke\u003c\/td\u003e\n\u003ctd\u003e1994–1995\u003c\/td\u003e\n\u003ctd\u003e340975, 340976, 18-3673\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eJohnson\/Evinrude\u003c\/td\u003e\n\u003ctd\u003eV4 Crossflow\u003c\/td\u003e\n\u003ctd\u003e115\u003c\/td\u003e\n\u003ctd\u003e2-Stroke\u003c\/td\u003e\n\u003ctd\u003e1978–1995\u003c\/td\u003e\n\u003ctd\u003e340975, 340976, 18-3673\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eJohnson\/Evinrude\u003c\/td\u003e\n\u003ctd\u003eV4 Crossflow\u003c\/td\u003e\n\u003ctd\u003e140\u003c\/td\u003e\n\u003ctd\u003e2-Stroke\u003c\/td\u003e\n\u003ctd\u003e1978–1985\u003c\/td\u003e\n\u003ctd\u003e340975, 340976, 18-3673\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\u003eMarine Outboard Thermostat Kit\u003c\/dd\u003e\n  \u003cdt\u003eInstallation\u003c\/dt\u003e\n\u003cdd\u003eDirect OEM replacement\u003c\/dd\u003e\n  \u003cdt\u003eFuel Type\u003c\/dt\u003e\n\u003cdd\u003eGasoline\u003c\/dd\u003e\n  \u003cdt\u003eConnection\u003c\/dt\u003e\n\u003cdd\u003eFactory OEM fit for V4 Crossflow design\u003c\/dd\u003e\n  \u003cdt\u003eHousing Material\u003c\/dt\u003e\n\u003cdd\u003eStainless steel (thermostat component)\u003c\/dd\u003e\n  \u003cdt\u003eHousing Color\u003c\/dt\u003e\n\u003cdd\u003eSilver\/metallic\u003c\/dd\u003e\n  \u003cdt\u003ePackage Dimensions\u003c\/dt\u003e\n\u003cdd\u003eApprox. 20.4 × 10.3 × 4.2 cm (8.03 × 4.06 × 1.65 in)\u003c\/dd\u003e\n  \u003cdt\u003eWeight\u003c\/dt\u003e\n\u003cdd\u003eApprox. 0.23 kg (8.1 oz)\u003c\/dd\u003e\n  \u003cdt\u003eFitting Type\u003c\/dt\u003e\n\u003cdd\u003eOEM-style fittings\u003c\/dd\u003e\n  \u003cdt\u003eOperating Temperature\u003c\/dt\u003e\n\u003cdd\u003e143°F (62°C) thermostat rating\u003c\/dd\u003e\n  \u003cdt\u003eWarranty\u003c\/dt\u003e\n\u003cdd\u003eManufacturer dependent, typically 1 year\u003c\/dd\u003e\n  \u003cdt\u003eOther Technical Attributes\u003c\/dt\u003e\n\u003cdd\u003eComplete kit with starboard and port hoses for V4 Crossflow dual thermostat system\u003c\/dd\u003e\n\u003c\/dl\u003e\n\n\u003ch2\u003eWhat’s in the Box\u003c\/h2\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cspan style=\"color:#d0021b;\"\u003e2 x\u003c\/span\u003e Thermostat (Replaces 18-3543, 393659, 434841, 378065, 508626, 5005440)\u003c\/li\u003e\n  \u003cli\u003e\n\u003cspan style=\"color:#d0021b;\"\u003e2 x\u003c\/span\u003e Thermostat Gasket (Replaces 18-0675, 321932)\u003c\/li\u003e\n  \u003cli\u003e\n\u003cspan style=\"color:#d0021b;\"\u003e2 x\u003c\/span\u003e Gasket (Replaces 18-0977, 332369)\u003c\/li\u003e\n  \u003cli\u003e\n\u003cspan style=\"color:#d0021b;\"\u003e2 x\u003c\/span\u003e Poppet Relief Valve (Replaces 18-3564, 318395)\u003c\/li\u003e\n  \u003cli\u003e\n\u003cspan style=\"color:#d0021b;\"\u003e2 x\u003c\/span\u003e Grommet (Replaces 18-2391, 321692)\u003c\/li\u003e\n  \u003cli\u003e\n\u003cspan style=\"color:#d0021b;\"\u003e2 x\u003c\/span\u003e Valve Spring (Replaces 18-1243, 317245)\u003c\/li\u003e\n  \u003cli\u003e\n\u003cspan style=\"color:#d0021b;\"\u003e1 x\u003c\/span\u003e Starboard Hose (Replaces 18-70936, 321724, 340975)\u003c\/li\u003e\n  \u003cli\u003e\n\u003cspan style=\"color:#d0021b;\"\u003e1 x\u003c\/span\u003e Port Hose (Replaces 18-70937, 340976)\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eInstallation Notes\u003c\/h2\u003e\n\u003col\u003e\n  \u003cli\u003eDisconnect the battery and allow the engine to cool completely before starting.\u003c\/li\u003e\n  \u003cli\u003eLocate the thermostat housings on the engine. On V4 models, there are typically two.\u003c\/li\u003e\n  \u003cli\u003ePlace a drain pan under the engine and carefully drain the cooling system.\u003c\/li\u003e\n  \u003cli\u003eRemove the bolts securing the thermostat housing cover(s).\u003c\/li\u003e\n  \u003cli\u003eTake out the old thermostats, gaskets, poppet valves, and springs. Note their orientation.\u003c\/li\u003e\n  \u003cli\u003eThoroughly clean the mating surfaces of the housing and cover, removing any old gasket material.\u003c\/li\u003e\n  \u003cli\u003eInstall the new thermostats, gaskets, and associated components from the kit in the correct order.\u003c\/li\u003e\n  \u003cli\u003eReplace the port and starboard hoses with the new ones provided.\u003c\/li\u003e\n  \u003cli\u003eRe-secure the housing covers, tightening the bolts to the manufacturer's specified torque.\u003c\/li\u003e\n  \u003cli\u003eRefill the cooling system with the appropriate coolant, checking for any leaks.\u003c\/li\u003e\n  \u003cli\u003eReconnect the battery, start the engine, and let it run to confirm proper operating temperature.\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 outboard's thermostat is failing?\u003c\/summary\u003e\u003cp\u003eCommon signs of a faulty thermostat include engine overheating alarms, the engine running too cold (failing to reach operating temperature), erratic temperature gauge readings, and visible coolant leaks around the thermostat housing.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eWhat is the operating temperature of this thermostat kit?\u003c\/summary\u003e\u003cp\u003eThis kit includes thermostats rated for 143°F (62°C) to ensure your engine operates within its ideal temperature range for performance and longevity.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eIs this kit for a single or dual thermostat engine?\u003c\/summary\u003e\u003cp\u003eThis is a complete kit designed for the Johnson\/Evinrude V4 Crossflow dual thermostat system, which is why it includes two of each core component and both starboard and port hoses.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eHow often should an outboard thermostat be replaced?\u003c\/summary\u003e\u003cp\u003eFor preventative maintenance, it's recommended to inspect your thermostats annually and replace them every 2–3 years or 200–300 hours of use, especially if operating in saltwater, to prevent cooling system failures.\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 \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":50717910729019,"sku":"QM5005440TK","price":28.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0826\/8673\/8747\/files\/QM5005440TK.png?v=1762938232","url":"https:\/\/seasierra.com\/products\/thermostat-kit-fits-johnson-evinrude-v4-crossflow-65-140-hp-replaces-18-3673-340975-340976","provider":"SeaSierra","version":"1.0","type":"link"}