Parts for your 1990 Mitsubishi Pajero-Oil pump

1990 Mitsubishi Pajero oil pump — purpose and service advice

Technical sources confirm the 1990 Mitsubishi Pajero is fitted with an engine oil pump. Factory service manuals for the Pajero/Montero (Engine Overhaul – Lubrication) covering the 4D56 2.5 diesel, 4G54 2.6 petrol, and 6G72 3.0 V6 specify a crankshaft-driven internal oil pump. Mitsubishi’s ASA/CAPS parts catalogues list complete oil pump/front case assemblies and service parts for these engines, and the Haynes/Max Ellery manuals also describe oil pressure checks and oil pump service for the same models. So yes—this Pajero definitely uses an oil pump.

The oil pump’s job is simple but critical: it pulls oil from the sump, pressurises it, and feeds the crankshaft and cam bearings, lifters, timing components and, on turbo models, the turbocharger. On the 4D56 and 6G72 it’s a trochoid (rotor-style) pump integrated into the front cover and driven off the crankshaft. Keeping pressure up means reduced wear, better cooling of hot spots, quieter running, and much longer engine life—especially important for Aussie and Kiwi conditions with long stretches, towing and dusty tracks.

It’s not a routine replacement item, but it does rely on clean oil, the right viscosity and a clear pickup screen. As part of regular servicing, change oil and filter on time, use a quality anti-drainback filter, and keep an eye on any oil warning light flicker at hot idle. If oil pressure seems low, verify with a mechanical gauge before blaming the pump, worn bearings, a sticky relief valve, a leaking front cover gasket or a clogged pickup can all drop pressure.

• Common signs to investigate: hot idle oil light flicker, noisy lifters, bottom-end rumble, metal in the oil, or sudden changes in pressure readings.
• Good workshop practice when replacing: inspect and clean the pickup, renew the pump O-ring/front cover gasket, front crank seal and relief valve components, and prime the pump (packing the rotors and prelube) before first start. Always follow the workshop manual for clearances and torque settings.
• Extra checks on high-kilometre engines: bearing clearances, end float and front cover wear—no pump can rescue an engine that’s already loose.

For 4D56 diesels, a quality 15W-40 diesel oil that meets the appropriate API spec is typical, for 4G54/6G72 petrol engines, 10W-40 or 15W-40 to the correct API rating works well. In heavy-duty or short-trip use, shorter intervals (around 5,000–7,500 km) help keep the pump happy.

FAQs

Does a 1990 Pajero have an oil pump, and where is it?
Yes. All 1990 Pajero engines (4D56 diesel, 4G54 2.6, 6G72 3.0 V6) use a crank-driven internal oil pump mounted in the front cover. It draws oil from the sump via a pickup and sends it through the galleries to bearings, valvetrain and, on turbo models, the turbo.

When should the oil pump be replaced?
There’s no fixed interval. Replace it if verified low oil pressure persists after checking oil grade, filter quality, pickup blockage, relief valve function and bearing clearances. Many owners renew the pump during an overhaul or timing/front cover reseal on high-kilometre engines.

What maintenance helps the oil pump last?
Use the correct-grade oil and a quality filter with an anti-drainback valve, change them on time, and fix any leaks quickly. If the oil light flickers hot, don’t keep driving—confirm pressure with a gauge and investigate. Clean oil and a sound pickup do more for pump life than anything else.