Parts for your 1986 Mitsubishi Pajero-Radiator

1986 Mitsubishi Pajero Radiator — What it does and how to look after it

A radiator is absolutely fitted to the 1986 Mitsubishi Pajero. Authoritative technical sources — including the Mitsubishi Pajero (L040/L140) Factory Service Manual, the Gregory’s/ Haynes Pajero workshop manuals for 1983–1991 models, and the Mitsubishi ASA parts catalogue — all specify a liquid-cooled system with a crossflow radiator, an engine-driven viscous fan, and (on many A/C-equipped vehicles) an auxiliary electric fan.

On this classic 4x4, the radiator’s job is to shed the engine’s heat so it runs at the sweet spot for power and longevity. Coolant circulates through the block and head, picks up heat, then passes through the radiator core where air flow under the bonnet whisks that heat away. The thermostat regulates flow, the cap maintains pressure, and the overflow bottle catches expansion — all helping to prevent detonation, warped heads, and cooked oil. For both the 2.6-litre 4G54 petrol and the 2.5-litre 4D56 diesel, a healthy radiator is non‑negotiable, especially in Aussie and Kiwi summers or low‑range climbs.

As part of regular servicing, coolant should be replaced every 2 years or around 40–50,000 kilometres. Use a quality ethylene glycol coolant suitable for older Japanese alloys (often the familiar green IAT type) mixed 50/50 with demineralised water. Inspect hoses, clamps, the radiator cap, thermostat, and the viscous fan clutch. Keep the core clean — mud, seeds and bugs can pack the fins after off‑road work. If the gauge wanders, the heater goes cold under load, or there’s a sweet smell and white crust around tanks, it’s time for checks.

• Check coolant level stone cold, weekly.
• Pressure-test the cap and system if you’re chasing leaks.
• Don’t mix coolant types, flush thoroughly if changing chemistry.
• When refilling, park nose-up, turn the heater on hot, squeeze the upper hose to burp air, and recheck the level the next day.

When replacing a tired or blocked core, choose a quality OEM‑style copper/brass re-core or a well‑made alloy unit. Autos need the correct built‑in transmission cooler ports, manuals don’t. Fit new hoses, clamps, a fresh cap, and a thermostat while you’re there, and keep the shroud — it makes a big difference to airflow. Tourers and tower’s might consider a higher‑capacity core for extra thermal headroom in the outback or high country.

Popular questions

What coolant should go in a 1986 Pajero radiator?
For these first‑gen Pajeros, a quality ethylene glycol coolant compatible with older Japanese alloys (typically green IAT) is a safe bet. Mix 33–50% with demineralised water depending on climate. Avoid blending long‑life OAT with conventional coolants — if changing type, fully flush first.

How often should the radiator be flushed?
Every 2 years or 40–50,000 km is a practical interval. If the vehicle regularly tows, idles in heat, or tackles muddy tracks, shorten the interval and add a fin clean to the routine.

What are common signs the Pajero’s radiator or cooling system is struggling?
Overheating under load, fluctuating temperature readings, a sweet coolant smell, crusty deposits on tanks, discoloured or rusty coolant, and a fan clutch that either freewheels when hot or roars constantly are all red flags. Don’t ignore them — catching issues early can save a head gasket.