Mitsubishi Challenger: 4D56 timing belt and balance shaft belt — a snapped belt destroys the engine

The 2.5-litre 4D56 diesel in the PB/PC Challenger drives its camshaft with a rubber belt, not a chain, and it is an interference engine: if the belt lets go the pistons meet the valves and the engine is finished. Mitsubishi calls for replacement around 90,000 km. Behind the timing belt sits a second belt driving the balance shafts, and this is the part that catches people out — the balance shaft belt is known to shred early on this engine, and the debris and vibration it throws off can take the timing belt with it. The correct job replaces both belts, the tensioners and the water pump together, so a seller who says 'the timing belt has been done' but paid for one belt only has left the trap fully set. On any Challenger with no belt paperwork, assume the job is due now and price the car accordingly.

• A whine, whirr or rumble from the front of the engine that rises with revs
• New vibration through the car that was not there before, especially at idle
• No timing belt entry in the service book near the 90,000 km mark
• Rubber dust or belt debris visible around the front cover
• Engine turns over but will not start after a bang or a sudden stop

1. 1

   Start with the paperwork, because this is the fault where paperwork is the inspection: look through the service book and any invoices for a timing belt entry, note the kilometres it was done at, and check the invoice actually lists the balance shaft belt, tensioners and water pump rather than the timing belt alone.

2. 2

   Take a photo of that invoice.

3. 3

   With the bonnet up and the engine idling, stand at the front and listen along the belt end for a whine, whirr or rumble that rises and falls with revs — a balance shaft belt on the way out is often audible before it fails, or by ear at least gives you a reason to dig further.

4. 4

   Put your hand flat on the top of the engine at idle and feel for a coarse shake that was not in other cars you have driven.

5. 5

   Ask the seller directly when the belts were last done, and if the answer is vague, treat the full belt job as a cost you are taking on the day you buy it.

Parts involved: Timing belt.

≈A$1,100 to ≈A$8,280 at independent workshop rates, shown as an approximate guide in Australian dollars. That is for this job on its own, not for the car.

An estimate, converted to Australian dollars, for the repair as normally carried out. What a specific car costs depends on which part has failed and what it damaged on the way — treat this as the floor for a negotiation, not a quote.

• “When were the timing belt and balance shaft belt last replaced, and at what kilometres?”
• “Does the invoice include the balance shaft belt, tensioners and water pump?”
• “Has the engine ever been rebuilt or had valve work?”

The failure described above is documented in the sources below. The inspection instructions and the cost estimate are KickTyres’ own interpretation of them.

• ReDriven — 'Used Mitsubishi Challenger (PB/PC) review' cheat sheet: 90,000 km timing belt, reports of premature balance shaft belt failure
• Pajero 4WD Club of Victoria forum — '4D56 Balance shaft: what the hell does it do' thread on balance shaft belt failure taking out the timing belt
• JustAnswer Australia — '2010 PB Challenger balance belt whining noise' case