Parts for your 2005 Subaru Forester-Radiator cap

2005 Subaru Forester Radiator Cap — What it does, where it lives, and when to replace it

Based on Subaru technical documentation, a radiator cap is indeed used on the 2005 Subaru Forester. The Factory Service Manual for the 2005 Forester (Cooling section: Radiator Cap Inspection/Pressure Test), the 2005 Owner’s Manual cooling system guidance, and Subaru’s genuine parts catalogue (e.g., pressure cap part numbers commonly including 45137AE000) confirm a pressurised cap is fitted. On most 2005 Foresters, this pressure cap is mounted on the high-mounted coolant filler/header tank under the bonnet rather than on the top of the radiator itself, but it serves the same function.

For this Forester, the radiator cap is a small part doing a big job. It seals the cooling system and holds a set pressure so the coolant can run hotter without boiling, keeping the EJ engine happy on long Kiwi and Aussie drives. It also lets coolant move to and from the overflow bottle as temperatures change, maintaining the right level and preventing air from sneaking in.

When talking replacement, matching the pressure rating is critical. Most 2005 Forester non-turbo models use a 108 kPa (1.1 bar) cap, while turbo variants may specify a different rating depending on market and build—always check the cap label or the VIN-based parts listing. A genuine or high-quality equivalent cap keeps the pressure curve spot on.

Good reasons to replace the cap include age (rubber seals harden), unexplained coolant loss, crusty deposits around the cap neck, an upper hose that collapses as the engine cools, or overheating that shows up at highway speeds. As a preventative, many techs swap the cap every 4–5 years or about 80,000–100,000 km.

Safety first: only remove the cap when the engine is stone cold. Park level, let it sit, then cover the cap with a rag and crack it slowly to bleed any residual pressure. Inspect the sealing surfaces on the filler tank and clean off old residue. Fit the new cap squarely and turn until the tabs seat firmly.

As part of routine servicing, it’s smart to:

• Pressure-test the cap (and the system) to factory spec.
• Check the overflow hose for splits and good clamp tension.
• Use the correct Subaru-approved coolant mix and bleed the system via the header tank with the heater on hot to avoid air pockets.

A fresh, correct-spec radiator cap is cheap insurance against overheating, nuisance leaks, and early head-gasket dramas. It’s a small swap that helps the Forester stay cool across tough Aussie heat and long NZ climbs.

Popular questions

Where is the radiator cap on a 2005 Subaru Forester?
It’s typically on the high-mounted coolant filler/header tank near the top of the engine bay, not on the radiator itself. That elevated position helps purge air and makes filling and bleeding the system easier.

Look for a metal or composite tank with a pressure cap and a small hose running to the overflow bottle.

What pressure cap does a 2005 Forester take?
Most non-turbo models specify about 108 kPa (1.1 bar). Some turbo variants may list a different rating. Always match what’s printed on your existing cap or confirm via the vehicle’s VIN in the Subaru parts system to avoid cooling-system misbehaviour.

How often should the cap be replaced?
Many workshops recommend every 4–5 years or 80,000–100,000 km, or sooner if there are signs of trouble like coolant smell, staining at the neck, or a collapsed upper hose after cool-down. A quick pressure test during servicing is the easiest way to check its health.