Parts for your 2022 Mitsubishi Eclipse cross-Radiator cap

2022 Mitsubishi Eclipse Cross radiator cap: what it does and how to look after it

Based on Mitsubishi’s own technical literature — the Eclipse Cross Owner’s Manual (2022, Cooling and Maintenance sections) and the Mitsubishi Motors service information for the cooling system — the 2022 Eclipse Cross uses a sealed, pressurised cooling system with the pressure cap located on the plastic coolant reservoir (degassing/expansion tank). There isn’t a traditional cap on the radiator neck, but the reservoir cap performs the same “radiator-cap” job.

The Eclipse Cross’s radiator cap (fitted to the expansion tank) keeps the cooling system at the right pressure so coolant won’t boil too early, helps purge air, and allows coolant to expand into and return from the reservoir as temperatures change. When that cap gets tired — weak spring, perished rubber, damaged seal — pressure control goes out the window. That’s when owners start chasing annoying issues like slow coolant loss, temperature swings under load, or hoses going rock-hard after a drive.

For servicing, it’s smart to treat the cap as a small but critical part. A technician should:

• Only remove the cap when the engine is cold — opening hot can cause scalding.
• Inspect the cap’s rubber seal, pressure spring movement and the tank’s neck for nicks or crusty deposits.
• Clean light residue from the seat, replace the cap if the seal is cracked, flattened, or the spring feels lazy.
• Pressure-test the cooling system and the cap if there are unexplained coolant losses or overheating complaints.

Replacement is inexpensive and preventative. Many workshops will proactively fit a new cap around major coolant service milestones or when the vehicle hits higher kilometres, especially in hotter Aussie and Kiwi conditions. Always match the cap to the Eclipse Cross by VIN or OEM part number — the pressure rating and seal design are specific. A genuine or high-quality equivalent cap helps keep the 1.5T/2.0 petrol cooling loop stable, protects the water pump, and maintains heater performance.

Signs it’s time for a new cap on a 2022 Eclipse Cross include:

• Frequent top-ups with no obvious leak
• Temperature gauge fluctuating on hills or in traffic
• Collapsed hose after cool-down or hose that’s abnormally hard when hot
• Coolant staining around the cap or a chemical smell under the bonnet

Simple part, big job — keeping that cap healthy is cheap insurance for the cooling system.

Popular questions

Where is the radiator cap on a 2022 Mitsubishi Eclipse Cross?
It sits on the pressurised coolant reservoir (expansion/degassing tank) rather than on the radiator itself. That cap controls system pressure and coolant flow to and from the tank. Always remove it only when the engine is cold.

How often should the radiator cap be replaced?
There’s no strict time-only rule, but it should be inspected at every service and replaced whenever the seal is perished, the spring is weak, or if there are pressure-related cooling issues. Many workshops replace it preventatively when doing a major coolant service or at higher kilometres.

Can an old radiator cap cause overheating?
Yes. A cap that can’t hold the correct pressure lowers the coolant’s boiling point and can let air into the system, both of which can lead to overheating, erratic temperatures, or coolant loss under load.