{"product_id":"thermostat-kit-fits-mercury-mariner-70-125-hp-2-stroke-replaces-803061t1-803061t02","title":"Thermostat Kit – Fits Mercury\/Mariner 70–125 HP 2-Stroke (Replaces 803061T1, 803061T02)","description":"\u003csection\u003e\n\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 \u003cstrong\u003eThermostat Kit – Fits Mercury\/Mariner 70–125 HP 2-Stroke (Replaces 803061T1)\u003c\/strong\u003e is designed for a range of Mercury and Mariner outboards from 1987 and newer. It is compatible with 3-cylinder models (70, 75, 80, 90 HP) and 4-cylinder models (100, 115, 125 HP), ensuring reliable engine temperature regulation for optimal performance.\u003c\/p\u003e\n\u003cp\u003eThis kit serves as a direct interchange for Sierra 18-3569, GLM 13124, Mallory 9-43155, and Mercury 803061T1\/803061T02.\u003c\/p\u003e\n\u003cul\u003e\n    \u003cli\u003eEngineered for direct OEM-replacement installation.\u003c\/li\u003e\n    \u003cli\u003eComplete kit includes the thermostat, gasket, and seal.\u003c\/li\u003e\n    \u003cli\u003eMaintains a consistent operating temperature of 50°C (120°F).\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 Cross-Reference\"\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\u003e18-3569\u003c\/td\u003e\n      \u003c\/tr\u003e\n       \u003ctr\u003e\n        \u003ctd\u003eGLM\u003c\/td\u003e\n        \u003ctd\u003e13124\u003c\/td\u003e\n      \u003c\/tr\u003e\n       \u003ctr\u003e\n        \u003ctd\u003eMallory\u003c\/td\u003e\n        \u003ctd\u003e9-43155\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eMercury\u003c\/td\u003e\n        \u003ctd\u003e803061T1 \/ 803061T02\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 thermostat kit is designed for a range of Mercury and Mariner 3-cylinder and 4-cylinder 2-stroke outboards from 1987 and newer.\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\u003eMercury\u003c\/td\u003e\n        \u003ctd\u003e3-cyl\u003c\/td\u003e\n        \u003ctd\u003e70\u003c\/td\u003e\n        \u003ctd\u003e2-Stroke\u003c\/td\u003e\n        \u003ctd\u003e1987 and newer\u003c\/td\u003e\n        \u003ctd\u003e803061T1\u003c\/td\u003e\n        \u003ctd\u003eA996142 \u0026amp; UP\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eMercury\u003c\/td\u003e\n        \u003ctd\u003e3-cyl\u003c\/td\u003e\n        \u003ctd\u003e75\u003c\/td\u003e\n        \u003ctd\u003e2-Stroke\u003c\/td\u003e\n        \u003ctd\u003e1987 and newer\u003c\/td\u003e\n        \u003ctd\u003e803061T1\u003c\/td\u003e\n        \u003ctd\u003eC222000 \u0026amp; UP\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eMercury\u003c\/td\u003e\n        \u003ctd\u003e3-cyl\u003c\/td\u003e\n        \u003ctd\u003e80\u003c\/td\u003e\n        \u003ctd\u003e2-Stroke\u003c\/td\u003e\n        \u003ctd\u003e1987 and newer\u003c\/td\u003e\n        \u003ctd\u003e803061T1\u003c\/td\u003e\n        \u003ctd\u003eA996142 \u0026amp; UP\u003c\/td\u003e\n      \u003c\/tr\u003e\n       \u003ctr\u003e\n        \u003ctd\u003eMercury\u003c\/td\u003e\n        \u003ctd\u003e3-cyl\u003c\/td\u003e\n        \u003ctd\u003e85\u003c\/td\u003e\n        \u003ctd\u003e2-Stroke\u003c\/td\u003e\n        \u003ctd\u003e1987 and newer\u003c\/td\u003e\n        \u003ctd\u003e803061T1\u003c\/td\u003e\n        \u003ctd\u003e\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eMercury\u003c\/td\u003e\n        \u003ctd\u003e3-cyl\u003c\/td\u003e\n        \u003ctd\u003e90\u003c\/td\u003e\n        \u003ctd\u003e2-Stroke\u003c\/td\u003e\n        \u003ctd\u003e1987 and newer\u003c\/td\u003e\n        \u003ctd\u003e803061T1\u003c\/td\u003e\n        \u003ctd\u003eA996142 \u0026amp; UP\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eMercury\u003c\/td\u003e\n        \u003ctd\u003e4-cyl\u003c\/td\u003e\n        \u003ctd\u003e100\u003c\/td\u003e\n        \u003ctd\u003e2-Stroke\u003c\/td\u003e\n        \u003ctd\u003e1987 and newer\u003c\/td\u003e\n        \u003ctd\u003e803061T1\u003c\/td\u003e\n        \u003ctd\u003eB209468 \u0026amp; UP\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eMercury\u003c\/td\u003e\n        \u003ctd\u003e4-cyl\u003c\/td\u003e\n        \u003ctd\u003e115\u003c\/td\u003e\n        \u003ctd\u003e2-Stroke\u003c\/td\u003e\n        \u003ctd\u003e1987 and newer\u003c\/td\u003e\n        \u003ctd\u003e803061T1\u003c\/td\u003e\n        \u003ctd\u003eC100000 \u0026amp; UP\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eMercury\u003c\/td\u003e\n        \u003ctd\u003e4-cyl\u003c\/td\u003e\n        \u003ctd\u003e125\u003c\/td\u003e\n        \u003ctd\u003e2-Stroke\u003c\/td\u003e\n        \u003ctd\u003e1987 and newer\u003c\/td\u003e\n        \u003ctd\u003e803061T1\u003c\/td\u003e\n        \u003ctd\u003eD283222 \u0026amp; UP\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\u003eThermostat 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\u003eOperating Temperature\u003c\/dt\u003e\n\u003cdd\u003e50°C \/ 120°F\u003c\/dd\u003e\n  \u003cdt\u003eWeight\u003c\/dt\u003e\n\u003cdd\u003e0.1 kg (0.22 lbs)\u003c\/dd\u003e\n  \u003cdt\u003eWarranty\u003c\/dt\u003e\n\u003cdd\u003eLimited Lifetime (Sierra)\u003c\/dd\u003e\n  \u003cdt\u003eIncluded Components\u003c\/dt\u003e\n\u003cdd\u003eComplete kit includes thermostat, gasket and seal\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 (18-3549)\u003c\/li\u003e\n  \u003cli\u003e1 x Thermostat Gasket (18-0182)\u003c\/li\u003e\n  \u003cli\u003e1 x Thermostat Cover Gasket (18-0339)\u003c\/li\u003e\n\u003c\/ul\u003e\n\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\u003eDrain the engine block coolant into a suitable container.\u003c\/li\u003e\n    \u003cli\u003eLocate and unbolt the thermostat housing cover.\u003c\/li\u003e\n    \u003cli\u003eCarefully remove the old thermostat and discard the old gaskets\/seals.\u003c\/li\u003e\n    \u003cli\u003eThoroughly clean the mating surfaces of the housing and cover, removing any old gasket material or corrosion.\u003c\/li\u003e\n    \u003cli\u003eInstall the new thermostat, ensuring it is oriented correctly.\u003c\/li\u003e\n    \u003cli\u003ePlace the new gaskets and seals in their correct positions.\u003c\/li\u003e\n    \u003cli\u003eRe-install 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.\u003c\/li\u003e\n    \u003cli\u003eReconnect the battery, start the engine, and check for any leaks around the housing as the engine warms up.\u003c\/li\u003e\n\u003c\/ol\u003e\n\n\u003ch2\u003eTroubleshooting \u0026amp; FAQ\u003c\/h2\u003e\n\u003cdetails\u003e\n  \u003csummary\u003eHow do I know if my thermostat has failed?\u003c\/summary\u003e\n  \u003cp\u003eCommon signs of a faulty thermostat include the engine overheating at idle or low speeds, or taking an unusually long time to reach its proper operating temperature. You might also receive temperature alarms from your gauges.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n  \u003csummary\u003eWhat is the correct operating temperature for this thermostat?\u003c\/summary\u003e\n  \u003cp\u003eThis thermostat is designed to open at 50°C (120°F), helping the engine maintain a stable temperature for efficient operation.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n  \u003csummary\u003eWill this fit my specific engine serial number?\u003c\/summary\u003e\n  \u003cp\u003eThis kit fits a wide range of Mercury\/Mariner engines from 1987 and newer. To ensure a perfect match, please compare your engine's serial number against the ranges listed in the compatibility table (e.g., \"A996142 \u0026amp; UP\").\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n  \u003csummary\u003eWhat's the difference between this kit and the OEM part?\u003c\/summary\u003e\n  \u003cp\u003eThis aftermarket kit is manufactured to meet or exceed original equipment (OEM) specifications for fit, form, and function. It provides a cost-effective solution and includes all necessary gaskets for a complete installation.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n  \u003csummary\u003eHow often should I replace my outboard's thermostat?\u003c\/summary\u003e\n  \u003cp\u003eFor preventative maintenance, it's good practice to inspect the thermostat annually and consider replacement every 2-3 years, especially when operating in saltwater environments. Replace it immediately if you notice signs of failure.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n  \u003csummary\u003eIs this an OEM part or an aftermarket replacement?\u003c\/summary\u003e\n  \u003cp\u003eThis listing is an aftermarket replacement (not OEM). It is built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility, it is batch-inspected for consistency and quality.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n  \u003csummary\u003eWhat are the shipping speed and cost?\u003c\/summary\u003e\n  \u003cp\u003eWe ship worldwide quickly—typical transit time is 5–15 days. Standard shipping is free for most orders; expedited options will appear at checkout if available for your location.\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 product is covered by a 1-year warranty against manufacturing defects under normal use. If you encounter any issues, please contact our support team with your order details. Returns are accepted within our standard window for items that are unused and in their original condition. See our policy page or reach out for instructions.\u003c\/p\u003e\n\u003c\/details\u003e\n\n\u003ch2\u003eSafety \u0026amp; Important Info\u003c\/h2\u003e\n\u003cul\u003e\n  \u003cli\u003eVerify images and specifications against your original part before purchasing. If anything differs—even if your model appears compatible—do not purchase.\u003c\/li\u003e\n  \u003cli\u003eThis is an aftermarket replacement part, not an original equipment manufacturer (OEM) component.\u003c\/li\u003e\n  \u003cli\u003eProfessional installation is highly recommended for safety and optimal 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 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 an average transit time of 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\n\u003c\/section\u003e","brand":"SeaSierra","offers":[{"title":"Default Title","offer_id":50718242963771,"sku":"803061T1-QM","price":19.5,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0826\/8673\/8747\/files\/803061T1-QM.png?v=1762958086","url":"https:\/\/seasierra.com\/products\/thermostat-kit-fits-mercury-mariner-70-125-hp-2-stroke-replaces-803061t1-803061t02","provider":"SeaSierra","version":"1.0","type":"link"}