Parts for your 1999 Mitsubishi Pajero-Exhaust gasket

1999 Mitsubishi Pajero exhaust-gasket: what it does, and when to replace it

Yes, the 1999 Mitsubishi Pajero uses exhaust gaskets. Factory documentation and parts catalogues confirm gaskets at the exhaust manifold-to-cylinder head and at the front pipe/flange joints (often a crush “donut” ring), across both petrol (6G72 3.0L and 6G74 3.5L V6) and diesel (4M40 2.8TD) variants. Technical sources referenced: Mitsubishi Pajero/Montero Workshop Manual (1997–2002) – Group 11 Engine (Exhaust Manifold) and Group 15 Exhaust System, Mitsubishi ASA Electronic Parts Catalogue for V20/V60 series, Haynes Manual for Mitsubishi Montero/Pajero (1992–2004), and common aftermarket gasket catalogues that list manifold and flange gaskets for these engines.

The exhaust gasket’s job is simple but critical: it seals super‑hot gases as they leave the head and move through the manifold and front pipe. A good seal keeps noise down, stops fumes getting where they shouldn’t, protects oxygen sensor readings on petrol models, and helps maintain low‑down torque and fuel economy. Pajero engines typically use multi‑layer steel or graphite/composite manifold gaskets and a metal/graphite crush ring at the manifold-to-front pipe or Y‑pipe. These crush under correct torque to create a gas‑tight joint even as the pipes expand and contract with heat and corrugations.

There’s no fixed replacement interval, gaskets are replaced when there’s a leak or whenever the joint has been disturbed. For a 1999 Pajero that sees off‑road work, water crossings, or regular towing, inspection during scheduled servicing is a smart move.

• Common signs of a leaking exhaust gasket:
  • Sharp ticking on cold start that fades warm
  • Sooty marks at the manifold or flange
  • Exhaust pong in the cabin or under‑bonnet
  • Sluggish response, poorer economy, on petrol models, possible O2 sensor/mixture fault codes
• Good practice when replacing:
  • Use OEM‑quality gaskets, replace spring bolts and the donut ring at flange joints
  • Soak rusty hardware with penetrant, heat helps on stubborn studs
  • Clean mating faces, chase threads, replace cracked studs
  • Tighten to workshop‑manual torque in sequence, re‑check after a couple of heat cycles if specified
  • Inspect hangers and mounts so the system isn’t pre‑loaded and stressing the new seal

Diesel 4M40 owners should also note the turbo/exhaust inlet and EGR pipe gaskets—any leak pre‑turbo hurts spool and drivability. Petrol V6s are sensitive to upstream leaks that skew O2 readings, so a tidy seal keeps the ECU happy and the fuel trims in check.

Popular questions

How can someone tell if the Pajero’s exhaust manifold gasket is blown?
Cold‑start ticking from the manifold area, black soot trails on the head or heat shields, and a whiff of fumes near the firewall are dead giveaways. On petrol V6s, a leak before the O2 sensor can trigger mixture‑related fault codes and a rough idle. A smoke test or soapy‑water check (watch for bubbles) helps confirm it without pulling gear off.

Which gasket type does a 1999 Pajero usually use at the front pipe?
Most 6G72/6G74 and 4M40 setups use a crush “donut” ring with spring‑loaded bolts at the manifold/front pipe or Y‑pipe. It allows a bit of movement off‑road while staying sealed. Whenever that joint is undone, replacing the ring and the spring bolts saves dramas later.

Is it safe to keep driving with a small exhaust gasket leak?
It will usually drive, but it’s not wise. Hot gas can erode flanges and studs, fumes can enter the cabin, and on petrol models the ECU may dump in extra fuel, hurting economy and the catalytic converter. Best to sort it promptly and avoid bigger bills.