Parts for your 1991 Mitsubishi Pajero-Harmonic balancers

1991 Mitsubishi Pajero Harmonic Balancer (Crankshaft Damper)

Technical sources including the Mitsubishi Pajero/Montero Factory Service Manual (engine mechanical section) and the Mitsubishi ASA electronic parts catalogue identify a crankshaft pulley with an integral vibration damper (harmonic balancer) on 1991 Pajero engines such as the 2.5L 4D56 turbo‑diesel, the 2.6L 4G54 petrol, and the 3.0L V6 6G72. Aftermarket catalogues from well-known suppliers in Australia and New Zealand (e.g., Powerbond, Dayco, Gates) also list replacement harmonic balancers for these engines. So yes—this model does use a harmonic balancer, and it’s a normal service item.

On a 1991 Pajero, the harmonic balancer’s job is to soak up crankshaft torsional vibrations so they don’t rattle the bottom end to bits. It’s a two-piece pulley with a bonded rubber layer between the hub and the outer ring. That rubber is the hero: it tunes out the crank’s twisty pulses, protects bearings and gears, and helps keep accessory belts running smooth. On engines like the 4D56 and 4G54, the outer ring also carries timing marks—if the rubber slips, those marks drift and timing goes out the window.

Because the rubber works hard and ages with heat, oil, and ozone, owners should treat the balancer as inspect-and-replace consumable. A good rule of thumb in local conditions is to inspect it at every major service or belt change, typically every 40,000–60,000 km, and any time the front of the engine is apart. Look for:

• Cracked, perished, or bulging rubber between the hub and outer ring
• Wobble at idle, belt misalignment, or chirping/squealing noises
• Timing marks that no longer line up reliably
• Oil contamination around the pulley (often from a weeping front main seal)

If replacement’s needed, it’s straightforward with the right tools. Lock the crank securely, remove the belts, and undo the crank bolt. Many workshop manuals for these engines specify a high final torque and/or angle—follow the factory procedure, use a quality puller to avoid damaging the seal, and don’t lever against the timing case. Fit the new balancer fully home on the keyway, confirm the outer ring/timing marks are true, and torque the crank bolt to spec, a new bolt and threadlocker are often recommended by OEM procedures. While you’re there, check the front main seal, drive belts, and the condition of the key/keyway. Avoid solid “underdrive” alloy pulleys on these engines—the factory used a damper for a reason, and deleting it can invite vibration and drivetrain wear.

Look after the balancer and the Pajero’s bottom end will thank them with smoother running, cleaner belt tracking, and fewer nasty vibrations through the cabin and drivetrain.

Popular questions

What are the common symptoms of a failing harmonic balancer on a 1991 Pajero?

Owners usually notice a wobbly crank pulley at idle, belt squeal, or a rhythmic vibration that wasn’t there before. Perished or separating rubber, wandering timing marks, and a chirp that changes with revs are big clues. If ignored, the pulley can shift enough to throw belts or upset ignition/injection timing.

How hard is it to replace the balancer at home?

It’s a moderate DIY task: belts off, crank bolt out, pulley pulled with a proper puller, then refit and torque correctly. The biggest hurdle is usually the very tight crank bolt. A crank locking tool or strong rattle gun helps. Always follow the workshop manual for torque/angle and check the front seal while you’re there.

Should the crank bolt be replaced and threadlocker used?

Many factory procedures for these Mitsubishi engines call for a new bolt and specified thread preparation. Because the clamping force is critical to prevent pulley movement, it’s smart practice to use a new OEM-quality bolt and the thread treatment specified in the manual.