{"product_id":"fasworx-outboard-thermostat-housing-kit-for-mercury-mariner-40-60hp-110-f-oem-style-replacement","title":"FASWORX Outboard Thermostat \u0026 Housing Kit for Mercury Mariner 40–60hp — 110°F OEM-style replacement","description":"\u003cp\u003e\u003cstrong\u003eFASWORX Outboard Thermostat \u0026amp; Housing Kit is a direct-fit replacement for Mercury Mariner 40–60hp 3-cylinder 2-stroke engines, restoring proper coolant flow with a 110°F thermostat element.\u003c\/strong\u003e\u003c\/p\u003e\n\n\u003cp\u003eIf your Mercury Mariner outboard is running hot, leaking around the thermostat housing, or you need a factory-style replacement after maintenance, this kit provides the thermostat and housing engineered to match OEM fitment. It replaces part numbers such as 850055A2, 850055A1, and 59078A2 and fits specified serial ranges for 40, 50, 55, and 60 horsepower models. The kit arrives ready to install, helping you avoid extended downtime and uncertain repairs.\u003c\/p\u003e\n\n\u003ch3\u003eWhich Mercury Mariner engines will this thermostat kit fit?\u003c\/h3\u003e\n\u003cp\u003eThis kit is designed for 3-cylinder 2-stroke Mercury Mariner outboards in the 40–60hp range within specified serial number windows. Confirm your engine’s serial number to ensure compatibility before ordering.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003e40 hp: USA serials 0G531301 and up; BEL serials 9855139 and up\u003c\/li\u003e\n  \u003cli\u003e50\/55\/60 hp: USA serials 0G590000 and up; BEL serials 9973100 and up\u003c\/li\u003e\n  \u003cli\u003eReplaces OEM codes 850055A2, 850055A1, 59078A2\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eHow does the 110°F thermostat affect engine performance?\u003c\/h3\u003e\n\u003cp\u003eThe included 110°F (approximately 43°C) thermostat opens at a controlled temperature to allow coolant circulation, helping the engine reach and maintain optimal operating temperature. Proper thermostat function supports consistent engine warm-up and reduces the risk of overcooling or overheating in varied water conditions.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003e110°F opening point for balanced warm-up and cooling\u003c\/li\u003e\n  \u003cli\u003ePrecision spring and valve design for repeatable operation\u003c\/li\u003e\n  \u003cli\u003eHelps stabilize running temperature under load and idle\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eWhat comes in the kit and is installation difficult?\u003c\/h3\u003e\n\u003cp\u003eThe kit includes the thermostat element and the housing designed to mate with Mercury Mariner water jackets and hoses. Installation is straightforward for anyone familiar with outboard maintenance; basic tools and a clean gasket surface are all that's needed for a secure seal.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eThermostat element sized for Mariner 3-cylinder 2-stroke engines\u003c\/li\u003e\n  \u003cli\u003eReplacement housing molded to OEM shape and mounting points\u003c\/li\u003e\n  \u003cli\u003eNo special tools required—follow torque specs and gasket prep\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eHow can I tell if my current thermostat or housing needs replacement?\u003c\/h3\u003e\n\u003cp\u003eSigns include inconsistent engine temperature gauge readings, visibly corroded or cracked housing, coolant leaks around the housing, or poor warm-up behavior. If the thermostat sticks closed or open, the engine may overheat or run too cool, both of which reduce efficiency and increase wear.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eVisible coolant leakage at the housing seams or gasket\u003c\/li\u003e\n  \u003cli\u003eEngine takes too long to reach operating temperature\u003c\/li\u003e\n  \u003cli\u003eFrequent temperature fluctuations under steady throttle\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003eWho this kit is for: Boaters, marine technicians, and DIYers who own Mercury Mariner 40–60hp 3-cylinder 2-stroke outboards within the listed serial ranges and need a reliable, OEM-style thermostat and housing replacement. Choose FASWORX when you want a direct-fit part that replaces legacy numbers (850055A2, 850055A1, 59078A2) and helps restore correct coolant control quickly and confidently.\u003c\/p\u003e\n\u003csection class=\"product-faq-snippet\"\u003e\u003ch3\u003eFAQ\u003c\/h3\u003e\n\u003cdiv class=\"faq-item\"\u003e\n\u003cp class=\"faq-q\"\u003eQ: Does this kit replace part number 850055A2?\u003c\/p\u003e\n\u003cp class=\"faq-a\"\u003eA: Yes. This FASWORX kit is a direct replacement for 850055A2 and related OEM numbers.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"faq-item\"\u003e\n\u003cp class=\"faq-q\"\u003eQ: Can I install the kit myself?\u003c\/p\u003e\n\u003cp class=\"faq-a\"\u003eA: Yes. Basic hand tools and proper gasket prep are sufficient for a competent DIY mechanic.\u003c\/p\u003e\n\u003c\/div\u003e\u003c\/section\u003e","brand":"FASWORX","offers":[{"title":"Default Title","offer_id":48084097794206,"sku":"B0BHX7L6RL","price":68.75,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0781\/2041\/9486\/files\/fasworx-thermostat-housing-front-view.jpg?v=1785846335","url":"https:\/\/northtrailauto.ca\/products\/fasworx-outboard-thermostat-housing-kit-for-mercury-mariner-40-60hp-110-f-oem-style-replacement","provider":"North Trail Auto","version":"1.0","type":"link"}