Parts for your 2016 Subaru Forester-Radiator cap

2016 Subaru Forester radiator cap: what it does, where it is, and when to replace it

Per Subaru technical references (SJ Forester Cooling System section of the Subaru Service Manual and the Subaru parts catalogue for MY2016), the 2016 Subaru Forester absolutely uses a pressure radiator cap — it’s simply not on the radiator neck. Instead, it’s fitted to the high-mounted pressurised filler/header tank (often called the expansion tank). So while the radiator itself doesn’t have a cap, the pressure cap is very much part of the system and still commonly called the “radiator cap”.

On a 2016 Forester, that cap’s job is to hold the cooling system at a set pressure so the coolant’s boiling point is raised, helping the engine run at the right temperature even on scorching Aussie or Kiwi days. It also allows coolant to move to and from the overflow bottle as things heat up and cool down, keeping everything tidy under the bonnet.

During routine servicing, it’s wise to treat the cap like a small but critical safety valve. A tired cap can cause hard-to-trace dramas — slow coolant loss, sudden overheating at highway speeds, hoses collapsing as the engine cools, or a heater that runs lukewarm. If any of that shows up, the cap is cheap insurance.

Good practice for Forester owners and workshops alike:

• Only remove the cap when the engine is fully cold, the system is pressurised and hot coolant can cause serious burns.
• Inspect the rubber seals, the spring, and the seating surface on the filler tank. Cracks, nicks, swelling, or corrosion mean it’s time to replace.
• Use the correct pressure rating and an OE-quality cap matched to the specific engine variant (FB25 petrol, FA20F turbo, or EE20 diesel, where fitted). The Subaru Service Manual and parts catalogue specify the rating by model/engine.
• If you’re replacing the cap, consider it alongside a coolant service. Bleed the system properly from the filler tank, run the heater on hot, and use a spill-free funnel to purge air.
• Re-check the coolant level in the filler tank and overflow bottle over the next few heat cycles.

There’s no fixed change interval for the cap, but checking it at each service and replacing it at the first sign of wear — or proactively every few years or after a cooling-system repair — keeps the Forester happy and helps avoid overheating grief.

Popular questions

Where is the radiator cap on a 2016 Subaru Forester?
It’s on the pressurised filler/header tank, mounted higher than the radiator, not on the radiator itself. Subaru designed the SJ Forester’s system this way to make bleeding easier and to keep the highest point — and the pressure cap — away from the radiator core.

What pressure radiator cap does a 2016 Forester use?
The correct pressure rating depends on the engine variant. Subaru specifies the cap rating in the Service Manual and parts catalogue for each engine (e.g., FB25 petrol versus FA20F turbo). Always match the OE rating noted for the exact VIN to ensure proper boiling margin and correct overflow/return operation.

What are the signs a Forester’s radiator cap needs replacing?
Common clues include coolant pushing out into the overflow bottle and not returning, collapsed upper hose after cool-down, unexplained coolant loss, intermittent overheating, or a crusty/flattened seal on the cap. If any of these show up, test or replace the cap and check the filler tank seat as well.