Parts for your 1998 Mitsubishi Pajero-Thermostat

1998 Mitsubishi Pajero Thermostat — What it does and when to replace it

Technical sources confirm a thermostat is fitted and absolutely relevant on the 1998 Mitsubishi Pajero. The Mitsubishi Motors Factory Service Manual (Cooling System section), the Mitsubishi ASA electronic parts catalogue, and well-known aftermarket manuals for 1990s Pajero models all specify a wax‑pellet thermostat for both petrol (V6) and diesel variants.

On a ’98 Pajero, the thermostat’s job is to help the engine reach and hold the right operating temperature. It stays closed when the engine’s cold so it warms up quickly, then opens to let coolant circulate through the radiator once it’s up to temp. That steady temperature helps fuel economy, keeps emissions in check, reduces engine wear, and gives reliable cabin heater performance. Typical opening temps are around 82–88°C for the V6 petrol engines and roughly 76–82°C for the 2.8‑litre turbo‑diesel, but always match the rating to the specific engine code and spec.

It’s a small part that has a big say in how the Pajero behaves. A stuck‑open thermostat can make it run cool, chew more fuel, and deliver weak heater output. Stuck closed, it can overheat under load—never ideal on a long haul with a van on the back.

• Common signs it’s time: slow warm‑up, temp gauge wandering, poor heater, overheating, or fans running more than usual.
• Good times to replace: during a cooling system overhaul, when doing the water pump or timing belt on V6 models, or if the vehicle’s history is unknown.

Replacement is straightforward for a competent home mechanic, but follow the workshop specs. Fit an OEM‑quality thermostat of the correct rating, orient the jiggle pin/bleed valve at 12 o’clock, and always use a new gasket or O‑ring. Clean the housing faces, tighten the cover bolts evenly to the factory torque, then refill with quality long‑life coolant mixed with demineralised water (about 50/50 unless specified otherwise). Bleed air with the heater on full hot, top up the overflow bottle after the first drive, and check for leaks.

Coolant should be renewed every 2–4 years depending on type and climate. The thermostat isn’t strictly a scheduled replacement item, but on a high‑kilometre Pajero (150–200k km) or one that’s seen heavy touring, proactive replacement is cheap insurance.

FAQs

Where is the thermostat on a 1998 Pajero?
On V6 petrol models it sits under the thermostat housing at the front of the engine where the upper radiator hose meets the engine. On the 2.8‑litre turbo‑diesel, it’s also at the front of the engine in the water outlet housing. Access is typically from under the bonnet with basic hand tools.

What temperature rating should be used?
Most V6 petrol engines use around 82–88°C, while the 2.8‑litre diesel commonly uses a lower rating in the 76–82°C range. Always choose the rating specified for the exact engine and market spec, as listed in the factory manual or parts catalogue.

Does the jiggle pin need to face up?
Yes. The small bleed valve (jiggle pin) should sit at 12 o’clock during installation to help purge trapped air and keep the cooling system stable. Skipping this simple step can cause slow warm‑up or temperature swings.