{"product_id":"sierra-18-3549-thermostat-120f-johnson-evinrude-omc","title":"Sierra 18-3549 Thermostat 120°F – Johnson Evinrude OMC Replacement","description":"\u003cp data-start=\"198\" data-end=\"457\"\u003eThe \u003cstrong data-start=\"202\" data-end=\"239\"\u003eSierra 18-3549 Thermostat (120°F)\u003c\/strong\u003e is a premium aftermarket replacement designed for Johnson, Evinrude, and OMC outboard engines. It regulates engine temperature to ensure proper warm-up and consistent cooling system performance in marine environments.\u003c\/p\u003e\n\u003cp data-start=\"459\" data-end=\"777\"\u003eCalibrated to \u003cstrong data-start=\"473\" data-end=\"489\"\u003e120°F (49°C)\u003c\/strong\u003e, this thermostat is ideal for 2-stroke outboard applications, helping maintain optimal operating temperature while preventing overheating and improving engine efficiency. Built to meet or exceed OEM specifications, it delivers dependable performance in both freshwater and saltwater use.\u003c\/p\u003e\n\u003chr data-start=\"779\" data-end=\"782\"\u003e\n\u003ch2 data-start=\"784\" data-end=\"803\"\u003e\u003cspan role=\"text\"\u003e\u003cstrong data-start=\"787\" data-end=\"803\"\u003eKey Features\u003c\/strong\u003e\u003c\/span\u003e\u003c\/h2\u003e\n\u003cul data-start=\"804\" data-end=\"1019\"\u003e\n\u003cli data-start=\"804\" data-end=\"846\"\u003eSierra premium aftermarket replacement\u003c\/li\u003e\n\u003cli data-start=\"847\" data-end=\"886\"\u003e\u003cstrong data-start=\"849\" data-end=\"884\"\u003e120°F (49°C) temperature rating\u003c\/strong\u003e\u003c\/li\u003e\n\u003cli data-start=\"887\" data-end=\"936\"\u003eMaintains proper engine operating temperature\u003c\/li\u003e\n\u003cli data-start=\"937\" data-end=\"975\"\u003eImproves cooling system efficiency\u003c\/li\u003e\n\u003cli data-start=\"976\" data-end=\"1019\"\u003eCorrosion-resistant marine construction\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003chr data-start=\"1021\" data-end=\"1024\"\u003e\n\u003ch2 data-start=\"1026\" data-end=\"1053\"\u003e\u003cspan role=\"text\"\u003e\u003cstrong data-start=\"1029\" data-end=\"1053\"\u003eEngine Compatibility\u003c\/strong\u003e\u003c\/span\u003e\u003c\/h2\u003e\n\u003ch3 data-start=\"1055\" data-end=\"1097\"\u003e\u003cspan role=\"text\"\u003e\u003cstrong data-start=\"1059\" data-end=\"1097\"\u003eJohnson \/ Evinrude \/ OMC Outboards\u003c\/strong\u003e\u003c\/span\u003e\u003c\/h3\u003e\n\u003cp data-start=\"1098\" data-end=\"1115\"\u003eCommonly used on:\u003c\/p\u003e\n\u003cul data-start=\"1116\" data-end=\"1219\"\u003e\n\u003cli data-start=\"1116\" data-end=\"1140\"\u003e2HP – 40HP outboards\u003c\/li\u003e\n\u003cli data-start=\"1141\" data-end=\"1184\"\u003eMany 2-stroke Johnson \u0026amp; Evinrude models\u003c\/li\u003e\n\u003cli data-start=\"1185\" data-end=\"1219\"\u003eOMC small to mid-range engines\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp data-start=\"1221\" data-end=\"1282\"\u003e➡️ Widely used across \u003cstrong data-start=\"1243\" data-end=\"1282\"\u003eolder carbureted outboard platforms\u003c\/strong\u003e\u003c\/p\u003e\n\u003chr data-start=\"1284\" data-end=\"1287\"\u003e\n\u003ch2 data-start=\"1289\" data-end=\"1326\"\u003e\u003cspan role=\"text\"\u003e\u003cstrong data-start=\"1292\" data-end=\"1324\"\u003eSerial Number Fitment Notice\u003c\/strong\u003e\u003c\/span\u003e\u003c\/h2\u003e\n\u003cp data-start=\"1327\" data-end=\"1346\"\u003eFitment depends on:\u003c\/p\u003e\n\u003cul data-start=\"1347\" data-end=\"1398\"\u003e\n\u003cli data-start=\"1347\" data-end=\"1372\"\u003eEngine model and year\u003c\/li\u003e\n\u003cli data-start=\"1373\" data-end=\"1398\"\u003eCooling system design\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp data-start=\"1400\" data-end=\"1494\"\u003e⚠️ Always confirm compatibility using your \u003cstrong data-start=\"1443\" data-end=\"1477\"\u003eengine model and serial number\u003c\/strong\u003e before ordering.\u003c\/p\u003e\n\u003chr data-start=\"1496\" data-end=\"1499\"\u003e\n\u003ch2 data-start=\"1501\" data-end=\"1522\"\u003e\u003cspan role=\"text\"\u003e\u003cstrong data-start=\"1504\" data-end=\"1522\"\u003eSpecifications\u003c\/strong\u003e\u003c\/span\u003e\u003c\/h2\u003e\n\u003cul data-start=\"1523\" data-end=\"1709\"\u003e\n\u003cli data-start=\"1523\" data-end=\"1551\"\u003ePart Number: \u003cstrong data-start=\"1538\" data-end=\"1549\"\u003e18-3549\u003c\/strong\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"1552\" data-end=\"1592\"\u003eTemperature Rating: \u003cstrong data-start=\"1574\" data-end=\"1590\"\u003e120°F (49°C)\u003c\/strong\u003e\n\u003c\/li\u003e\n\u003cli data-start=\"1593\" data-end=\"1620\"\u003eType: Engine thermostat\u003c\/li\u003e\n\u003cli data-start=\"1621\" data-end=\"1664\"\u003eFunction: Regulates coolant temperature\u003c\/li\u003e\n\u003cli data-start=\"1665\" data-end=\"1709\"\u003eConstruction: Marine-grade metal housing\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003chr data-start=\"1711\" data-end=\"1714\"\u003e\n\u003ch2 data-start=\"1716\" data-end=\"1738\"\u003e\u003cspan role=\"text\"\u003e\u003cstrong data-start=\"1719\" data-end=\"1738\"\u003eWhat’s Included\u003c\/strong\u003e\u003c\/span\u003e\u003c\/h2\u003e\n\u003cul data-start=\"1739\" data-end=\"1798\"\u003e\n\u003cli data-start=\"1739\" data-end=\"1798\"\u003eThermostat (gasket\/seal sold separately unless specified)\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003chr data-start=\"1800\" data-end=\"1803\"\u003e\n\u003ch2 data-start=\"1805\" data-end=\"1844\"\u003e\u003cspan role=\"text\"\u003e\u003cstrong data-start=\"1808\" data-end=\"1844\"\u003eWhen This Part Needs Replacement\u003c\/strong\u003e\u003c\/span\u003e\u003c\/h2\u003e\n\u003cp data-start=\"1845\" data-end=\"1882\"\u003eReplace the thermostat if you notice:\u003c\/p\u003e\n\u003cul data-start=\"1883\" data-end=\"1997\"\u003e\n\u003cli data-start=\"1883\" data-end=\"1905\"\u003eEngine overheating\u003c\/li\u003e\n\u003cli data-start=\"1906\" data-end=\"1933\"\u003eEngine running too cold\u003c\/li\u003e\n\u003cli data-start=\"1934\" data-end=\"1959\"\u003ePoor idle performance\u003c\/li\u003e\n\u003cli data-start=\"1960\" data-end=\"1997\"\u003eInconsistent temperature readings\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003chr data-start=\"1999\" data-end=\"2002\"\u003e\n\u003ch2 data-start=\"2004\" data-end=\"2029\"\u003e\u003cspan role=\"text\"\u003e\u003cstrong data-start=\"2007\" data-end=\"2029\"\u003eInstallation Notes\u003c\/strong\u003e\u003c\/span\u003e\u003c\/h2\u003e\n\u003cul data-start=\"2030\" data-end=\"2188\"\u003e\n\u003cli data-start=\"2030\" data-end=\"2076\"\u003eReplace gasket or seal during installation\u003c\/li\u003e\n\u003cli data-start=\"2077\" data-end=\"2106\"\u003eEnsure proper orientation\u003c\/li\u003e\n\u003cli data-start=\"2107\" data-end=\"2150\"\u003eInspect housing for corrosion or debris\u003c\/li\u003e\n\u003cli data-start=\"2151\" data-end=\"2188\"\u003eTest cooling system after install\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003chr data-start=\"2190\" data-end=\"2193\"\u003e\n\u003ch2 data-start=\"2195\" data-end=\"2237\"\u003e\u003cspan role=\"text\"\u003e\u003cstrong data-start=\"2198\" data-end=\"2237\"\u003eAlternate \/ Superseded Part Numbers\u003c\/strong\u003e\u003c\/span\u003e\u003c\/h2\u003e\n\u003ch3 data-start=\"2239\" data-end=\"2267\"\u003e\u003cspan role=\"text\"\u003e\u003cstrong data-start=\"2243\" data-end=\"2267\"\u003eOEM Cross References\u003c\/strong\u003e\u003c\/span\u003e\u003c\/h3\u003e\n\u003cul data-start=\"2268\" data-end=\"2318\"\u003e\n\u003cli data-start=\"2268\" data-end=\"2318\"\u003eOMC \/ Johnson \/ Evinrude: \u003cstrong data-start=\"2296\" data-end=\"2316\"\u003e384891 \/ 5005440\u003c\/strong\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003chr data-start=\"2320\" data-end=\"2323\"\u003e\n\u003ch3 data-start=\"2325\" data-end=\"2361\"\u003e\u003cspan role=\"text\"\u003e\u003cstrong data-start=\"2329\" data-end=\"2361\"\u003eAftermarket Cross References\u003c\/strong\u003e\u003c\/span\u003e\u003c\/h3\u003e\n\u003cul data-start=\"2362\" data-end=\"2385\"\u003e\n\u003cli data-start=\"2362\" data-end=\"2385\"\u003eSierra: \u003cstrong data-start=\"2372\" data-end=\"2383\"\u003e18-3549\u003c\/strong\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003chr data-start=\"2387\" data-end=\"2390\"\u003e\n\u003ch2 data-start=\"2392\" data-end=\"2409\"\u003e\u003cspan role=\"text\"\u003e\u003cstrong data-start=\"2395\" data-end=\"2407\"\u003eShipping\u003c\/strong\u003e\u003c\/span\u003e\u003c\/h2\u003e\n\u003cp data-start=\"2410\" data-end=\"2475\"\u003eShipping: Ships same or next day for fast Canada wide shipping. ⚓\u003c\/p\u003e\n\u003chr data-start=\"2477\" data-end=\"2480\"\u003e\n\u003ch3 data-start=\"2482\" data-end=\"2509\"\u003e💡 Parts Desk Insight\u003c\/h3\u003e\n\u003cp data-start=\"2510\" data-end=\"2646\" data-is-last-node=\"\" data-is-only-node=\"\"\u003eOn older Johnson\/Evinrude 2-strokes, a stuck-open thermostat will make the engine run cold and rough—this is one of the easiest fixes 👍\u003c\/p\u003e\n\u003cp\u003e.\u003c\/p\u003e","brand":"WEST","offers":[{"title":"Default Title","offer_id":43564241322020,"sku":"SIE-18-3549","price":43.75,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0743\/5799\/7604\/files\/45bc619d-e946-441f-8fc4-c81a1fcc09f2.png?v=1774376776","url":"https:\/\/marisolmarine.com\/products\/sierra-18-3549-thermostat-120f-johnson-evinrude-omc","provider":"Marisol Marine Company","version":"1.0","type":"link"}