Parts for your 2001 Subaru Forester-Thermostat

2001 Subaru Forester Thermostat — Purpose, Care, and When to Replace

Technical sources including the Subaru Factory Service Manual for the 2001 Forester (EJ-series engines), the Subaru Genuine Parts Catalogue (thermostat and gasket listings), and the Haynes Subaru Forester Service & Repair Manual all confirm this model is fitted with a conventional wax‑pellet engine coolant thermostat. It sits in the lower radiator hose housing on the water pump, and controls coolant flow to keep the engine at the right operating temperature.

On a 2001 Forester, the thermostat’s job is simple but crucial: help the engine warm up quickly, then hold a steady temperature for efficient running. It typically begins to open around 78–82°C and is fully open near the mid‑90s, routing coolant through the radiator when needed. That means better fuel economy, smoother driving, proper heater performance and less wear on cold starts.

As part of routine servicing, it’s smart to give the thermostat some attention whenever the cooling system is opened up. Many owners replace it preventively at major intervals (for example when doing a timing belt and water pump) or every 7–10 years/150,000–200,000 km. Always use a genuine or OEM‑spec thermostat and the correct gasket/seal