Parts for your 1987 Mitsubishi Pajero-Radiator cap

1987 Mitsubishi Pajero radiator cap — what it does and how to look after it

Yes, the 1987 Mitsubishi Pajero uses a conventional radiator cap mounted on the radiator’s top tank. This setup is detailed in Mitsubishi’s Pajero (L040/L141) Workshop Manual cooling system section and echoed in popular service references like the Haynes Mitsubishi Pajero/Montero manual, which specify a pressure-type cap (typically around 0.9 bar/13 psi) working with an overflow bottle.

On a first‑gen Pajero, the radiator cap is more than just a lid — it’s a pressure valve that lets the cooling system run hotter without boiling, keeping the engine happy when towing, climbing, or slogging through summer heat. By holding pressure to its rated value, it raises the coolant’s boiling point. When pressure exceeds the rating, the cap vents smoothly to the overflow bottle, as things cool down, its vacuum valve draws coolant back, preventing hose collapse and air pockets. That’s why the cap’s rubber seals and spring tension matter just as much as the coolant itself.

Owners should treat the cap as a service item. At each service (about every 10,000–15,000 kilometres on an older 4WD), check the cap’s seals for cracks, hardness, or nicks, make sure the spring moves freely, and confirm the overflow hose is tight and unblocked. If there’s any doubt, a quick pressure-cap test with a cooling-system tester will tell the story. Many workshops replace the cap at coolant change time (often every two years) because it’s inexpensive insurance on a 1987 vehicle.

• Choose the correct pressure rating (commonly 0.9 bar/13 psi for the 1987 Pajero, verify against the vehicle label or workshop manual).
• Match the cap style to the radiator neck (JIS-style Japanese neck on most first‑gen Pajeros).
• Only remove the cap when the engine is stone cold. If needed, turn to the first stop to bleed pressure, then remove.

Signs the cap may be tired include creeping temperatures at low speed, coolant pushing into the overflow and not returning, a sweet coolant smell after shutdown, visible weeping at the neck, or a top hose that collapses as the engine cools. Sorting the cap first can save chasing phantom overheating faults. For a rugged truck like the ’87 Pajero — whether 2.6 petrol or 2.5 diesel — a healthy radiator cap keeps the whole cooling system behaving as it should, on-road and off.

Popular questions about 1987 Mitsubishi Pajero radiator caps

What pressure radiator cap does a 1987 Mitsubishi Pajero use?
Most 1987 Pajeros run a cap rated around 0.9 bar (13 psi). That figure appears in workshop literature for first‑gen models and is common across both petrol and diesel variants. Always double‑check the vehicle’s under‑bonnet label or a trusted workshop manual to confirm your exact spec.

Where is the radiator cap on a 1987 Pajero, and how do you open it safely?
It’s on the radiator’s top tank under the bonnet. Only open it when the engine is completely cold. Place a rag over the cap, turn it to the first detent to vent any residual pressure, then press down and turn fully off. If it hisses or spits, stop and let it cool longer.

What are the symptoms of a failing radiator cap on this model?
Look for coolant overflowing into the bottle and not returning, rising temps in traffic, a collapsed upper hose after cooldown, staining around the neck, or a persistent coolant smell. Any of these can point to a weak spring or hardened seals inside the cap.