Parts for your 1990 Mitsubishi Pajero-Coolant

1990 Mitsubishi Pajero Coolant — what it does and how to look after it

Coolant absolutely is used on the 1990 Mitsubishi Pajero. The factory Mitsubishi workshop manuals for the era, along with well-known Haynes and Gregory’s guides covering late-80s/early-90s Pajeros, all detail a conventional liquid-cooled system with a radiator, thermostat, water pump and heater core. So coolant isn’t just relevant — it’s essential to how this Pajero keeps its engine happy.

In this model, coolant does a few key jobs. It carries heat away from the engine to prevent overheating, lifts the boiling point and lowers the freezing point, and protects the alloy and steel parts inside the block, head, radiator and heater core from corrosion and scale. It also lubricates the water pump’s seals. That all adds up to steadier temps, better heater performance on cold mornings, and a longer life for pricey components under the bonnet.

For servicing, owners should use a quality ethylene glycol–based coolant that meets Mitsubishi’s spec for the period (typically the green conventional type). A 50/50 mix with demineralised water is the common target for our climate across Australia and New Zealand. Don’t mix different coolant chemistries, if the coolant type is unknown, it’s safer to fully flush and refill. Most 1990 Pajero engines take roughly 8–10 litres across the system, depending on whether it’s a petrol V6 or a diesel, but always check the specific engine details in the service manual.

As a rule of thumb for older cooling systems running conventional coolant, a complete change every 2 years or around 40,000–50,000 km is sensible, with a quick inspection at every service. Discoloured coolant, a sweet smell, temperature creep under load, or a low overflow bottle are all flags to act on. When refilling, set the heater to hot, top up slowly, and bleed air so the gauge stays stable and the heater runs toasty.

• Use demineralised water for mixing and flushing to reduce scale.
• Inspect hoses, clamps, radiator cap and the water pump weep hole.
• Replace the thermostat if temps fluctuate or warm-up is sluggish.
• Dispose of old coolant responsibly — it’s toxic to pets and wildlife.

What coolant type and mix does a 1990 Mitsubishi Pajero use?

A quality ethylene glycol–based coolant that meets Mitsubishi’s period specs is recommended — typically the green conventional type. Run it at about 50/50 with demineralised water for balanced freeze/boil protection and corrosion control. Avoid mixing different coolant chemistries, if switching types, flush completely first.

How often should the coolant be changed?

For a 1990 Pajero on conventional green coolant, plan on every 2 years or roughly 40,000–50,000 km. Check condition at each service: if it’s rusty, cloudy, or has lost its colour, bring the change forward. If a long-life formula is used, follow the product’s interval, but confirm compatibility with Mitsubishi guidance.

How do you bleed air from the cooling system after a refill?

Fill the radiator slowly with the heater set to hot, start the engine and let it idle with the cap off until the thermostat opens and bubbles subside. Top up as the level drops, fit the cap, then fill the overflow bottle to the mark. After a short drive and cool-down, recheck levels. Some engines may have a bleed point — if fitted, use it per the workshop manual.