Parts for your 2010 Subaru Tribeca-Radiator cap

2010 Subaru Tribeca radiator cap — location, purpose and service tips

Based on Subaru’s 2010 Tribeca Factory Service Manual (Cooling System section), the Owner’s Manual, and the Subaru electronic parts catalogue (which lists the cooling system pressure cap for the Tribeca, e.g., p/n 45137AE001/45137AE030 depending on market), this model does use a radiator-cap function. It’s fitted to a pressurised coolant filler/header tank mounted high in the engine bay, rather than on the radiator neck itself. So while you won’t find a cap on the radiator top tank, the system still relies on a dedicated pressure cap to manage coolant pressure and recovery.

On the 2010 Tribeca, the radiator-cap (pressure cap) is the small but critical valve that seals the cooling system, raises the coolant’s boiling point, and controls expansion and recovery between the header tank and overflow bottle. Under the bonnet, it sits on the pressurised filler tank at the system’s high point, which helps purge air and keeps the flat-six running cool even in harsh Aussie and Kiwi summers.

The cap contains a spring-loaded pressure valve and a vacuum valve. When coolant heats up and expands, the pressure valve opens at the rated pressure to move excess fluid to the overflow. As things cool, the vacuum valve draws coolant back in, preventing hose collapse and air pockets. If the cap’s spring weakens or its seals harden, you can see tell-tales like creeping temps, random coolant loss, the overflow bottle overfilling or staying oddly low, or hoses going flat after shutdown.

Good servicing practice is to treat the cap as a wear item. Under normal conditions, have it inspected at each service (around every 10,000 km) and replaced about every 5 years or 100,000 km, or sooner if there are signs of perishing, corrosion on the seat, or a failed pressure test. Always match Subaru’s specified pressure rating for your VIN — it’s printed on the cap face and confirmed in the service literature. Stick with quality OEM-spec parts to avoid nuisance overheating.

• Only remove the cap when the engine is stone cold.
• Check the rubber seals for nicks and hardening, replace if suspect.
• Wipe the filler neck seat clean before refitting.
• If you’ve had overheating or cooling work done, pressure-test the cap and system, and bleed air thoroughly.

Where is the radiator cap on a 2010 Subaru Tribeca?

It’s on the pressurised coolant filler/header tank, not on the radiator itself. Look for the metal or composite tank high in the engine bay with the warning label on the cap.

What pressure cap does the Tribeca use?

Subaru specifies a particular pressure rating for the model/VIN. The rating is printed on the cap face. Use an OEM-spec cap that matches the factory pressure to maintain correct boiling point and flow.

Is it safe to drive with a dodgy radiator cap?

Not recommended. A weak or leaking cap can cause overheating, coolant loss, or air ingestion. Replace it promptly and check for any other cooling-system issues.