Parts for your 1991 Mitsubishi Pajero-Sump plug washers

1991 Mitsubishi Pajero sump plug washers

Yes, a sump plug washer is used on the 1991 Mitsubishi Pajero. This is supported by the Mitsubishi Factory Service Manual for early-’90s Pajero (NA/NH series) in the Lubrication section, and by Mitsubishi’s ASA electronic parts catalogue, which lists a crush-type oil drain plug gasket for these engines (commonly an M14 aluminium gasket, with parts such as MD050317 appearing across relevant Pajero applications). So if the oil’s getting dropped, a fresh washer should be on hand.

The sump plug washer (also called a drain plug gasket) does a simple but critical job: it seals the drain plug to the sump so oil doesn’t seep out once the engine is hot and the oil’s thinned. On a 1991 Pajero—whether it’s a 4D56 diesel or 6G72 V6—the factory setup uses a soft crush washer that deforms once during tightening to create a reliable seal against the sump’s machined face.

Because it crushes, it’s effectively a single-use item. Reusing a flattened washer can lead to weeping, drips on the driveway, or worse, an owner cranking the plug too hard to “make it seal,” which risks stripping threads in the alloy sump. A new washer is cheap insurance every oil change.

For servicing, the best practice is:

• Remove the old washer with the plug and bin it—don’t try to flip or “freshen” it.
• Wipe the sump seat and plug head clean. Any grit can compromise the seal.
• Fit a correct-size crush washer (most 1991 Pajeros take an M14 aluminium washer, confirm against your engine variant or VIN).
• Tighten the plug to the workshop manual torque spec—firm, not gorilla-tight. Over-tightening won’t seal better, it just damages things.
• After filling, run the engine, then check for leaks. Recheck after a short drive.

Aluminium and copper crush washers both work, many Pajeros shipped with aluminium. Bonded rubber/metal styles exist, but the plain crush type remains the straightforward, reliable choice. If an aftermarket magnetic plug has been fitted, match the washer to that plug’s size and shoulder design.

Bottom line: replace the sump plug washer every time the oil’s changed. It keeps the big Mitsi tidy, avoids messy leaks, and protects the sump threads—too easy.

What size sump plug washer fits a 1991 Mitsubishi Pajero?

Most 1991 Pajeros use an M14 crush washer (14 mm internal diameter), typically aluminium. Because there were multiple engines and occasional market differences, it’s smart to check your old washer or confirm by VIN/engine code before buying a pack.

How often should the washer be replaced?

Every oil change. A crush washer is designed to deform once. Replacing it each time avoids drips, saves over-tightening drama, and keeps the sump threads safe.

Can the old washer be reused, or can thread tape be used instead?

Reusing isn’t recommended, and thread tape is a no-go on sump plugs. Use a fresh, correct-size crush washer—it’s cheap, seals properly, and won’t shed debris into the oil.