Parts for your 2017 Subaru Xv-Radiator cap

2017 Subaru XV radiator cap — what it does and how to look after it

Referencing technical sources including the Subaru Owner’s Manual for the 2017 XV/Crosstrek (cooling system cautions), the Subaru Service Manual for the FB20 engine (radiator cap opening pressure specification around 108 kPa/1.1 bar), and the Subaru parts catalogue (radiator cap e.g., 45137AE003), the 2017 Subaru XV does use a pressurised radiator cap. On this model it’s fitted to the alloy coolant filler tank (header tank) near the top of the engine, rather than directly on the plastic radiator.

The radiator cap on a 2017 Subaru XV is a small but critical part of the cooling system. Its main job is to hold pressure—about 1.1 bar—so coolant can run hotter without boiling, stabilising engine temperature on Aussie and Kiwi roads, whether it’s city crawls or long open-road stints. It’s also a two-way valve: when pressure gets too high it vents a little coolant to the overflow bottle, and as things cool, it draws coolant back to keep the system full and free of air.

As part of regular servicing, it’s smart to give the cap a good look. Under the bonnet, check the rubber seal for nicks or flattening, make sure the spring-loaded centre moves smoothly, and inspect the filler neck for corrosion or crusty deposits that could stop it sealing. A workshop can pressure-test the cap, if it can’t hold its rated pressure, it’s time for a new one.

Replacing the cap is inexpensive insurance. Many technicians in Australia and New Zealand recommend proactive replacement around 5 years or 100,000 km, or any time the cooling system is serviced (hoses, thermostat, or coolant flush). Always use the correct pressure rating specified for the XV’s FB20 engine—mixing ratings can cause overheating or hose damage.

• Common signs of a dodgy cap: unexplained coolant loss, overflow bottle boiling or overfilling, collapsed upper radiator hose after cool-down, gurgling sounds, or temperature swings.
• Never open the cap hot—let the engine cool completely. On the XV, fill and bleed via the header tank cap, then confirm the overflow hose is snug and the coolant level in the bottle sits between Low and Full when cold.

Popular questions about 2017 Subaru XV radiator caps

Where is the radiator cap on a 2017 Subaru XV?
On this model it’s on the alloy coolant filler tank (also called a header tank) positioned high at the front of the engine bay, not on the plastic radiator itself. Subaru places the cap at the highest point to make bleeding air easier and to keep the system properly pressurised.

What pressure rating should the XV’s radiator cap be?
The FB20 engine typically specifies an opening pressure around 108 kPa (about 1.1 bar). Stick with an OEM-equivalent cap to maintain the correct boiling point and hose protection. Using a cap with the wrong rating can lead to overheating or premature component wear.

How often should the radiator cap be replaced?
Have it inspected at each service and pressure-tested during cooling system work. Many mechanics suggest replacing the cap proactively every 5 years or 100,000 km, or immediately if it fails a pressure test, shows seal damage, or if there are cooling-system symptoms like unexplained coolant loss.