Parts for your 1990 Mitsubishi Pajero-Harmonic balancers

1990 Mitsubishi Pajero harmonic balancer — fitted, what it does, and how to look after it

A harmonic balancer is used on the 1990 Mitsubishi Pajero across its common engines of the era, including the 2.5L 4D56 turbo-diesel, the 2.6L 4G54 petrol, and the 3.0L 6G72 V6. Technical sources such as Mitsubishi’s factory workshop manuals for these engines list the crankshaft front pulley as a vibration damper (harmonic balancer) and provide removal/installation procedures. The Mitsubishi ASA electronic parts catalogue likewise identifies the crankshaft pulley assembly as a bonded rubber damper, and aftermarket service manuals (e.g., Gregory’s/Haynes for first‑gen Pajero) cover inspection and replacement. So yes — it’s relevant and it’s there under the bonnet.

On a 1990 Pajero, the harmonic balancer is the crankshaft pulley with a rubber-bonded ring that soaks up torsional vibrations from firing pulses. That little bit of rubber and mass keeps the crank happy, helps protect the timing components and accessories, and reduces noise and harshness. When it fails — often by the rubber delaminating or the outer ring slipping — timing marks go off, belts can wander or squeal, and in bad cases it can take out a belt or stress the crank nose.

As part of routine servicing, it’s worth giving the balancer a close look every 20,000–40,000 km, or whenever belts are off. With the engine off, check the pulley’s rubber layer for cracks, bulges, or separation, and make sure the outer ring hasn’t crept relative to the keyway/timing marks. Any wobble at idle with good belts fitted is a red flag.

• Common symptoms: chirping or squealing belts, visible pulley wobble, oil‑like smear from deteriorating rubber, timing marks that don’t line up despite correct base timing, or an intermittent vibration at certain revs.
• Replacement tips: use quality OEM or reputable aftermarket dampers, clean the crank nose and key, always fit a new bolt/washer if specified, and torque to the factory spec from the engine manual. A dab of correct thread preparation (where specified) helps keep the bolt from backing out.
• Good practice: replace accessory belts at the same time, recheck belt tension after a short run, and keep an eye on front crank seal condition while you’re in there.

Owners of 4D56 diesels in particular should be mindful, as age and heat cycles can harden the rubber. If there’s any doubt, replacing the balancer is cheap insurance against bigger dramas.

Popular questions about 1990 Mitsubishi Pajero harmonic balancers

How can someone tell if their Pajero’s harmonic balancer is failing?
They’ll usually spot a wobble at idle, hear belt noise, or see that the timing marks no longer make sense when setting base timing. A close look may show cracked or separated rubber between the hub and the outer ring. If belts and pulleys are sound yet there’s still a rhythmic vibration around certain revs, the balancer’s likely tired.

How often should a harmonic balancer be replaced on a 1990 Pajero?
There’s no strict interval — it’s condition‑based. Many original units last decades, but age, oil contamination, and heat take a toll. Inspect it at each major service, if the rubber shows cracking, the ring has shifted, or there’s any wobble, replace it straight away rather than waiting.

Can a failing harmonic balancer damage the engine?
Yes. Besides throwing belts, a failed damper can increase torsional stress on the crankshaft and timing components. On older engines like the 4D56, running long‑term with a bad balancer risks accelerated wear. Replacing a suspect unit early helps protect the crank nose, keyway, and accessories.