Parts for your 2002 Subaru Forester-Thermostat housing

2002 Subaru Forester thermostat housing

Based on technical references—including the Subaru Factory Service Manual (2002 Forester, Cooling System), Subaru’s Electronic Parts Catalogue (lists the “water inlet/thermostat case” bolted to the water pump), and general repair manuals (Haynes/Gregory’s for Subaru EJ engines)—the 2002 Subaru Forester does use a thermostat housing. On these EJ-series engines the housing, often called the water inlet or thermostat cover, clamps the thermostat in place at the lower radiator hose connection on the water pump.

On a 2002 Forester, the thermostat housing’s job is to secure the thermostat, seal the joint to the pump, and direct coolant from the lower hose into the engine. When the engine’s cold, the thermostat stays shut, keeping coolant circulating internally for a quicker warm-up. As it reaches operating temp, the thermostat opens and the housing channels flow to the radiator. Subaru positions this assembly low on the front of the engine, so it’s easy to spot once the bonnet’s up: follow the lower radiator hose to the alloy elbow/cover with two small bolts—there’s the housing.

During servicing, it’s smart to give the housing a look whenever coolant is flushed (typically every 2 years or 40,000–50,000 kilometres, or as per the owner’s schedule). Light surface corrosion is common on older alloy housings, but pitting around the sealing face, hairline cracks, or stubborn leaks mean it’s time for replacement. The thermostat on these cars seals with an integral rubber ring