Parts for your 1990 Mitsubishi Pajero-Manifold gasket

1990 Mitsubishi Pajero manifold gasket — what it does and how to look after it

Technical sources confirm the 1990 Mitsubishi Pajero does use manifold gaskets. The Mitsubishi factory service manuals for the 4G54 (2.6 petrol), 6G72 (3.0 V6) and 4D56 (2.5 turbo‑diesel) engines, along with the Mitsubishi ASA electronic parts catalogue and the Haynes Pajero/Montero 1983–1996 manual, all specify intake and exhaust manifold gaskets and outline torque procedures for refitting. So, yes — a manifold gasket is absolutely relevant on this model.

On these Pajeros, the intake manifold gasket seals the intake runners to prevent unmetered air sneaking in, keeping idle smooth and mixtures right. The exhaust manifold gasket seals hot gases as they exit the head, on the 4D56T it also copes with turbo heat and pressure. When these gaskets fail, they cause rough running, ticking leaks, fumes, and lost power or boost.

They’re not a regular “replace-by-kilometres” service item, but they’re common wear points with age, heat cycling and off‑road vibration. Smart servicing means inspecting them whenever the intake, exhaust, or turbo comes off — think cooling system work on the V6, carb/TBI jobs on the 4G54, or turbo/EGR work on the 4D56.

• Typical symptoms: intake leak — hunting idle, lean codes (on EFI), higher fuel use, exhaust leak — ticking on cold start, soot tracks, whiff of fumes, slower spool on the diesel.
• Good practice: use quality OEM or equivalent multi‑layer graphite/steel gaskets, avoid RTV on the sealing faces (except where the FSM calls for a dab at joints).
• Preparation: clean and de‑carbon surfaces without gouging, check manifold flatness — 4D56 exhaust manifolds can warp or crack if run hot.
• Fasteners: replace tired studs/nuts, chase threads, and torque in the factory sequence. After a few heat cycles on exhaust work, a recheck of nut torque helps.

For the V6 6G72, don’t forget the upper plenum gaskets when doing intake work, for the 4D56T, there’s also the turbo-to-manifold and downpipe gaskets. If a gasket leak is found, sort it promptly — it protects the head from heat damage, keeps mixtures right, and saves the cabin from fumes. A tidy seal means the old Paj keeps pulling hard and idling sweet, whether it’s tackling a gravel road or the school run.

Popular questions

What are the torque specs for the Pajero’s manifold bolts?

Specs vary by engine and location. As a guide, intake manifold bolts on the 6G72 and 4G54 are typically in the low-to-mid 20–30 Nm range, while exhaust manifold nuts are higher. Always follow the factory service manual sequence and values for your exact engine, uneven torque can warp the manifold or pinch the gasket.

Can a manifold leak damage the engine on a 4D56 turbo‑diesel?

Yes. An exhaust leak pre‑turbo can slow spool, hike EGTs, and soot up nearby components. An intake leak post‑turbo bleeds boost and can draw in dust. Left alone, that can mean hotter running, more fuel use, and extra stress on the head and turbo. Fix leaks early and check surfaces for flatness.

Should I use sealant with a new manifold gasket?

Generally no. The specified gaskets are designed to seal dry. Only use a tiny dab of the correct sealant where the factory manual explicitly calls for it, such as at joint steps. Excess sealant can squeeze out and create leaks or block passages.