Parts for your 2024 Mitsubishi Asx-Radiator cap

2024 Mitsubishi ASX radiator cap – what it does and how to look after it

For the AU/NZ‑spec 2024 Mitsubishi ASX (the long‑running GA‑series with the 2.0‑litre MIVEC), a conventional radiator cap is fitted on the radiator itself. This setup is confirmed in Mitsubishi’s workshop literature for GA2W/GA6W (Cooling System – Radiator Cap Inspection/Pressure Test) and the ASX Owner’s Manual notes and warnings regarding the radiator cap and overflow bottle. It’s not the newer sealed “degas bottle only” arrangement seen on some other models.

The radiator cap on the ASX is a pressure valve and safety device in one. By holding the cooling system at a set pressure (typically around 1.1 bar/108 kPa, as stamped on the cap), it raises the coolant’s boiling point so the engine can run efficiently without localised boiling. When pressure exceeds the rating, the cap vents coolant to the overflow bottle, as the system cools, the cap’s vacuum valve draws coolant back to keep the radiator full.

As part of regular servicing, the cap deserves a quick once‑over. A weak spring, nicked seal or sticky valve can lead to overheating, hard or collapsed hoses, or unexplained coolant loss. A technician will often pressure‑test the cap with a tester and replace it if it won’t hold the specified pressure.

• Safety first: never remove the radiator cap when hot. Wait until the engine is cold, then use a rag and open it slowly to bleed off any residual pressure.
• Inspect the rubber seal and seat for cracks, flattening, or deposits. Clean the neck if there’s crusty build‑up.
• Check the pressure rating on the cap matches the vehicle spec, stick with a quality OEM‑equivalent cap.
• If you’ve had overheating, hose collapse after cool‑down, or repeat coolant top‑ups, have the cap tested.

There’s no hard replacement interval, but it’s smart to inspect the cap at each service (about every 12 months/15,000 km) and replace it proactively if the seal looks tired, the spring feels weak, or the test result is borderline. When refilling coolant after a service, use the specified coolant type and correctly bleed air, a sound cap helps the system self‑purge via the overflow bottle during the first heat cycles.

Treat the radiator cap as a small, inexpensive part that protects a very expensive engine. Keeping it healthy helps the ASX run cool on scorching Aussie and Kiwi summer days, towing, or stop‑start city traffic.

Popular questions

Does the 2024 Mitsubishi ASX have a radiator cap?
Yes, the AU/NZ 2024 ASX uses a conventional pressurised radiator with a radiator cap, as described in Mitsubishi’s GA‑series workshop material and Owner’s Manual cooling‑system cautions. It’s not a sealed, cap‑on‑reservoir‑only design.

What pressure rating should the ASX radiator cap be?
Most ASX caps are around 1.1 bar (108 kPa). Always check the stamping on your existing cap and your service information to match the correct pressure rating for your vehicle.

Can coolant be topped up through the radiator cap?
Normally, top‑ups are done via the overflow/reservoir when the engine is cold. The radiator cap should only be opened when the engine is fully cold, such as after a drain/refill or when bleeding air per workshop procedure.