Thermostat Kit (160°F/71°C) – Fits Mercruiser 3.7L 4-Cylinder Engines (Replaces 99155T1, 99155T2) 390HP The most reliable method is

The most reliable method is to check your engine's model number and year against our compatibility table

Replacement intervals are set by the engine manufacturer and are typically based on operating hours or years of service (e

Place the new drive key in the shaft slot

Ensure all gaskets and seals were seated correctly to prevent air leaks

Thermostat Kit (160°F/71°C) – Fits Mercruiser 3.7L 4-Cylinder Engines (Replaces 99155T1, 99155T2) 390HP The most reliable method isProduct Details This aftermarket Thermostat Kit (160F 71C) is designed for Mercruiser 3. 7L 4 cylinder (224 CID) engines, including the 165, 170, 180, 190, 470, 485, and 488 series models manufactured between 19761989. It serves as a direct replacement for Mercruiser part numbers 99155T1 and 99155T2, and provides an interchange for Sierra parts 18 3555, 18 3568, and 18 3667. Designed for simple, direct OEM replacement installation. Regulates engine