Parts for your 1989 Mitsubishi Pajero-Sump plug washers

1989 Mitsubishi Pajero sump plug washers

A sump plug washer is absolutely fitted to the 1989 Mitsubishi Pajero. Factory documentation backs this up: the Mitsubishi Factory Service Manual for Pajero/Montero (Engine Lubrication section) specifies replacing the drain plug gasket during oil changes, and the Mitsubishi ASA Electronic Parts Catalogue lists the oil drain plug gasket (commonly MD050317, superseded in many kits by MZ690006) across key 1989 Pajero engines, including the 4D56 diesel, 4G54 four-cylinder, and 6G72 V6. General repair texts for the platform (such as Haynes coverage for 1983–1996 models) also call out a new crush washer at every oil change.

What does that little washer do? It’s a soft copper or aluminium crush washer that sits between the sump (oil pan) and the drain plug, deforming once on first tighten to fill tiny imperfections. That one-time “crush” creates a positive seal at the specified torque, so the plug doesn’t need to be over-tightened to stop drips. On older sumps and well-travelled Pajeros, a fresh washer is the simplest insurance against weeping oil and stripped threads.

On most 1989 Pajero engines the drain plug is M14 x 1.5 and uses a 14 mm ID crush washer. Copper or aluminium both work, many genuine and OEM options are available, with MD050317/MZ690006 being common Mitsubishi part references. Because there were several engines and regional specs in 1989, it’s smart to confirm by engine code or by measuring the old gasket before purchase.

As part of regular servicing, the washer should be replaced at each oil change. Reusing a crushed washer can lead to slow leaks, messy undersides, and the temptation to over-tighten the plug. The service-friendly approach is:

• Clean the sump seating face and plug head.
• Fit a new crush washer, correct size and material.
• Tighten the plug to the factory spec from the Pajero service manual.
• Warm the engine, then check for any seepage around the plug.
• If it still weeps, replace the washer again rather than cranking the plug harder.

Keeping a couple of spare washers in the toolbox is a no-brainer for Aussie and Kiwi owners who service their Pajero at home. If the plug head is rounded or the threads look tired, replace the plug as well—cheap protection for an engine that’s built to roam. A magnetic plug is a nice extra, but the humble crush washer is the real hero that keeps the oil where it should be.

Popular questions

What size sump plug washer does a 1989 Mitsubishi Pajero use?
Most 1989 Pajeros use a 14 mm internal diameter crush washer for an M14 x 1.5 drain plug, as shown in Mitsubishi parts listings (e.g., MD050317/MZ690006) for 4D56, 4G54, and 6G72 engines. Always check your engine code or match the old washer to be sure.

Should the sump plug washer be replaced at every oil change?
Yes. Mitsubishi service literature calls for installing a new drain plug gasket each time the oil is changed. It’s a one-use crush component, reusing it risks leaks and over-tightening.

Is copper or aluminium better for the Pajero’s sump plug washer?
Both are fine if sized correctly. Aluminium crushes easily and seals well, copper is robust and can sometimes be annealed in a pinch, but best practice for this model is to fit a new washer at each service, regardless of material.