Parts for your 2015 Mitsubishi Asx-Radiator cap

2015 Mitsubishi ASX radiator cap — what it does and when to replace it

Technical sources confirm a radiator cap is fitted to the 2015 Mitsubishi ASX. The Mitsubishi Motors workshop manual (Cooling System section), the Mitsubishi ASA electronic parts catalogue for GA-series ASX (2015MY), and AU/NZ aftermarket application guides from brands like Tridon and Gates all specify a pressurised radiator cap mounted on the radiator filler neck for ASX/RVR/Outlander Sport models of this year. So yes — it uses a traditional radiator cap, not a capless or reservoir-only setup.

On the 2015 ASX, the radiator cap is a pressure-control valve in disguise. It seals the cooling system, raises the boiling point of the coolant by maintaining the specified pressure, and manages expansion and contraction as the engine heats and cools. When things get hot, the cap lets excess coolant flow to the overflow bottle, as it cools, the vacuum valve draws coolant back, keeping the radiator brim-full. That helps prevent boil-over, air pockets, and temperature swings under the bonnet.

As part of regular servicing, the cap deserves a quick once-over. Only check it when the engine is stone cold. Look for cracked or flattened rubber seals, corrosion on the seat, weak spring tension, or staining around the filler neck. If there’s coolant loss with no obvious leaks, a collapsed upper hose after shutdown, or the overflow bottle keeps overfilling or staying empty, a tired cap is a prime suspect. Replacing a dodgy cap is cheap insurance against overheating and head gasket grief.

Use the correct pressure rating stamped on the original cap (commonly around 1.1 bar for many Mitsubishis, but always confirm against the handbook or parts catalogue). Avoid generic “one-size-fits-all” caps — the wrong pressure can cause premature hose, radiator, or heater-core failures. When fitting, clean the filler neck, seat the cap squarely, and twist until the latch is fully engaged. If the cooling system’s been opened, bleed it properly and recheck the coolant level after a few heat cycles.

As a rule of thumb, test or replace the radiator cap every 3–5 years or 60–100,000 kilometres, sooner if there are symptoms. During services, topping up with the specified coolant type and concentration (pre-mix or the correct demineralised water blend) keeps corrosion at bay and lets the cap do its job. A healthy cap helps the ASX run cool on scorching Aussie and Kiwi days, whether it’s weekday commuting or a long weekend getaway.

• Never open the radiator cap when hot — wait until fully cold.
• Match the pressure rating to OEM spec.
• Inspect seals and spring tension, replace if in doubt.
• Check the overflow hose for splits or kinks.

FAQs

What pressure radiator cap does a 2015 Mitsubishi ASX use?
Most 2015 ASX models use a cap around 1.1 bar (110 kPa), but Mitsubishi specifies by engine/market. The correct rating is stamped on the OE cap and listed in the owner’s handbook and parts catalogue. If in doubt, match the pressure on the original or consult a trusted parts supplier using the vehicle’s VIN.

How often should the radiator cap be replaced on a 2015 ASX?
Inspect it at every coolant service and replace it every 3–5 years or 60–100,000 kilometres, or immediately if it fails a pressure test or shows damage. Symptoms like coolant smell, fluctuating temperature, hose collapse after cooldown, or overflow bottle misbehaviour point to a weak cap.

Where is the radiator cap on the 2015 ASX?
It’s on the radiator filler neck at the front of the engine bay, under the bonnet. The translucent overflow bottle sits nearby. Only remove the cap when the engine is cold to avoid scalding from hot coolant and steam.