Parts for your 2000 Mitsubishi Pajero-Radiator cap

2000 Mitsubishi Pajero radiator cap — is it used?

For the 2000 Mitsubishi Pajero sold in Australia and New Zealand (NM series, 3rd generation launched in 2000), there isn’t a traditional radiator-mounted cap. Instead, the cooling system uses a pressurised expansion/header tank with the pressure cap fitted to that tank, not to the radiator neck. This layout is shown in the Mitsubishi Pajero NM/NP Factory Service Manual (Cooling System section) and backed up by Mitsubishi ASA parts catalogues and common workshop references like Gregory’s/Haynes, which list a pressure cap for the expansion tank rather than a radiator neck cap.

Why the change? Mitsubishi moved to a sealed radiator with a higher-mounted, pressurised header tank to make bleeding easier, keep a consistent static head of coolant over the engine, and improve packaging under the bonnet. The cap on the header tank still does the same job a “radiator cap” used to do—holding system pressure to raise the boiling point and managing coolant flow to and from the overflow—but it’s simply not on the radiator itself.

What this means for owners is that searching for a “radiator cap” for a 2000 Pajero can be a bit misleading, the correct service part is the pressure cap on the pressurised expansion/header tank. Typical rating is around 0.9 bar (13 psi), but always match what’s stamped on the existing cap or follow the vehicle’s service manual for the exact spec.

Good practice on these Pajeros is to check the header-tank cap at regular service intervals. Look for cracked or flattened rubber seals, a sticky or weak spring, and any crusty deposits around the neck that suggest venting. Replace the cap if there are signs of age or if you’re chasing intermittent overheating, hoses that collapse as the engine cools, or repeated coolant loss with no obvious leaks. Only remove the cap when the engine is stone cold. If topping up, use the correct premixed coolant and bleed air as per the workshop procedure to avoid hot spots and air locks.

Note: In some markets, a few run-out “early-2000 compliance” 2nd-gen Pajeros may still have a radiator-mounted cap. For NM/NP (3rd-gen, 2000-on AU/NZ), the cap is on the pressurised header tank.

• Location on 2000 NM/NP: Pressurised expansion/header tank (not on radiator)
• Typical rating: ~0.9 bar (confirm on the cap/manual)
• Service tip: Inspect/replace cap every few years or if cooling issues appear

Popular questions about the 2000 Mitsubishi Pajero radiator cap

Does a 2000 Pajero have a radiator cap on the radiator?
Most 2000 (NM/NP) Pajeros in AU/NZ do not have a cap on the radiator neck. The pressure cap is fitted to the pressurised expansion/header tank. That’s the cap you remove to fill and bleed the system—only when the engine is cold.

What pressure rating cap should be used?
The common spec is around 0.9 bar (13 psi), but always confirm what’s stamped on your existing cap or check the workshop manual for your exact engine variant. Using the wrong rating can cause overheating or push coolant out prematurely.

How can someone tell if the cap needs replacing?
Symptoms include coolant pushing into the overflow and not returning, collapsing hoses as the engine cools, random temp spikes, or visible damage to the cap’s rubber seal. If in doubt, replace the cap—it’s inexpensive and often cures elusive cooling gremlins.