Parts for your 2001 Subaru Forester-Thermostat housing

2001 Subaru Forester thermostat housing: what it does and how to look after it

Yes, the 2001 Subaru Forester uses a thermostat housing. Subaru’s Factory Service Manual for the 2001 Forester (Cooling section) and the Subaru FAST parts catalogue both show the thermostat mounted in the water pump and retained by a two-bolt “water outlet/thermostat cover” – commonly called the thermostat housing. This is the same arrangement across the EJ-series engines fitted to that model year, so the part is absolutely relevant to the vehicle.

On the Forester, the thermostat housing sits low at the front of the engine, behind the lower radiator hose under the bonnet. Its job is simple but critical: it clamps and seals the thermostat in the water pump, provides the outlet neck for the lower hose, and keeps the cooling system leak-free under pressure. If the housing warps, corrodes, or the sealing ring hardens, coolant can seep out and the engine can overheat – not the sort of drama anyone wants.

Servicing is straightforward. Whenever the thermostat is replaced (often done after a cooling system overhaul, overheating incident, or high kilometres), it’s smart to inspect the housing. Look for pitting around the sealing surface, cracks, or a crusty build-up where the hose clamps on. If it’s clean and flat, it can usually be reused