This water thermostat regulates coolant flow through the engine block to maintain operating temperature. It sits in the coolant circuit between the cylinder head outlet and the radiator inlet; when closed during warm-up, it bypasses the radiator to speed heat buildup, then opens at its rated temperature to allow full radiator flow. A stuck-closed thermostat causes overheating, while a stuck-open unit prevents the engine from reaching normal operating temperature, reducing efficiency and increasing wear. Granit manufactures this replacement to match the original housing bore and seal surface geometry, so no adapter or shimming is required during installation. Replace the gasket on reinstall and torque the housing bolts to specification.