Parts for your 2023 Mitsubishi Eclipse cross-Radiator cap

2023 Mitsubishi Eclipse Cross radiator cap — is it actually a thing?

Short answer: a traditional radiator cap on the radiator isn’t used on the 2023 Mitsubishi Eclipse Cross. Per Mitsubishi’s own technical literature — the 2023 Eclipse Cross Owner’s Manual (cooling system and coolant top-up instructions) and the Mitsubishi Motors Service Manual (Cooling System section) — the vehicle runs a sealed, pressurised cooling system that’s filled and regulated at a remote coolant reservoir (also called a degas or expansion tank). The radiator itself has no filler neck and therefore no separate radiator cap.

Why the change? Modern cooling systems mount a pressurised reservoir high in the engine bay so it becomes the single point for filling, air separation, and pressure control. The screw-on pressure cap on that reservoir does the old radiator cap’s jobs — maintaining system pressure to raise the coolant’s boiling point, and allowing excess pressure to vent and coolant to return as things cool. Designing it this way improves packaging under the bonnet, makes bleeding air simpler, reduces spill risk, and keeps hands clear of the radiator core when hot.

For Eclipse Cross owners, that means any talk of a “radiator cap” really refers to the reservoir’s pressure cap. It’s the bit that deserves attention at service time:

• Inspect the reservoir cap seal for cracks, flattening, or deposits, and replace if it’s hardened or swollen.
• If chasing overheating, hard hoses, or coolant loss, have a workshop pressure-test the system and the cap — a weak cap can cause boil-over and erratic temperatures.
• Use a genuine Mitsubishi cap or a quality equivalent that matches the specified pressure rating for this model, mixing ratings can trigger cooling issues.
• Only open the cap when the engine is stone cold. If it hisses when cold or you smell coolant, get it checked.

Coolant top-ups and changes are done via the reservoir. Use the correct Mitsubishi-approved long-life coolant (colour and spec as per the Owner’s Manual), don’t mix coolant types, and set the level to the “COLD” mark with the engine cool. After any cooling-system work, technicians will bleed via the reservoir while the thermostat cycles to purge trapped air.

Popular questions

Does the 2023 Mitsubishi Eclipse Cross have a radiator cap?
It doesn’t have a cap on the radiator itself. The system uses a pressurised coolant reservoir with a screw-on pressure cap that handles filling and pressure control. That’s the cap to inspect and replace if needed.

Where do you add coolant on a 2023 Eclipse Cross?
Top up only at the coolant reservoir when the engine is cold, filling to the “COLD” mark. Use the Mitsubishi-approved long-life coolant and avoid mixing brands or colours. If the level keeps dropping, have the system and cap tested.

When should the reservoir cap be replaced?
Have it checked at every service. Replace it if the seal is brittle, the spring action feels weak, there’s evidence of leakage or deposits, or after a cooling-system overheat event. Always match the correct pressure rating for this model.