Parts for your 2020 Subaru Xv-Radiator cap

2020 Subaru XV radiator cap — what it is, where it lives, and how to look after it

Referencing Subaru’s technical literature for this model (2020 XV/Crosstrek Owner’s Manual, Cooling system section, and the 2020 XV/FB20 Engine Service Manual, Cooling section), the radiator on the 2020 Subaru XV does not have a cap on the radiator neck. Instead, the system uses a pressurised coolant filler tank with a pressure cap mounted on that tank. So while there’s no “radiator-neck cap”, a radiator-cap function absolutely exists on this vehicle and is essential to cooling performance.

On the 2020 Subaru XV, the radiator cap’s job is to hold pressure in the cooling system so coolant can run hotter without boiling, then safely relieve pressure into the overflow bottle as the engine heats up, and draw coolant back as it cools. It also helps purge air and keeps the system sealed. Subaru places the pressure cap on the coolant filler tank near the top of the engine under the bonnet, rather than on the radiator itself, which aids in air separation and makes topping up easier.

As part of routine servicing, the cap should be visually checked whenever the cooling system is inspected. Only remove it when the engine is cold. Look for cracked or flattened rubber seals, corrosion or whitish crust at the filler neck, a sticky or weak spring, or any staining that suggests seepage. Workshops often pressure-test caps, if it doesn’t hold the specified pressure or the vacuum valve sticks, replacement is cheap insurance. Using a genuine Subaru cap or a high‑quality equivalent that matches the exact pressure rating specified for the vehicle is important for proper system operation.

Typical signs a failing cap may be causing grief include:

• Coolant pushed into the overflow bottle and not returning after cool-down
• Collapsed upper radiator hose after shut-down (vacuum valve not opening)
• Intermittent overheating at highway speeds or after long climbs
• Coolant smell or crusty deposits around the filler tank cap area

When replacing the cap, clean the filler neck, seat the new cap squarely, and tighten fully. After any cooling-system work, recheck levels in both the filler tank and overflow bottle over the next few heat cycles. Kept in good nick, the cap helps the XV stay cool in Aussie and Kiwi summers and on frosty South Island mornings alike.

Popular questions about the 2020 Subaru XV radiator cap

Where is the radiator cap on a 2020 Subaru XV?
It’s on the pressurised coolant filler tank under the bonnet, not on the radiator itself. The tank sits high in the engine bay so air can separate out, and the metal pressure cap is fitted to the top of that tank.

What pressure rating cap should the 2020 XV use?
Use a cap that exactly matches the pressure rating printed on the factory cap and listed in the owner’s manual/under‑bonnet label. Different engines and markets can specify different ratings, so matching the original specification is the safe bet.

Can a dodgy cap cause overheating or coolant loss?
Yes. If it can’t hold pressure, coolant may boil earlier and push into the overflow, if the vacuum valve sticks, coolant won’t return as the engine cools, leading to air pockets. Both scenarios can trigger temperature swings, weak cabin heat, or gradual coolant loss.