Mitsubishi Pajero: 6G74 3.5L V6 Balance Shaft Belt Failure and Engine Destruction

The 6G74 3.5-litre V6 petrol engine uses a secondary inner belt to drive the balance shafts, running in the same timing chest as the main cambelt. This inner balance shaft belt is prone to delamination and shedding at high mileage, particularly past 100,000 km if the engine has not had the full belt kit (including inner belt) replaced. When the inner belt sheds, rubber debris can jam the timing belt, causing it to skip or snap and resulting in piston-to-valve contact and catastrophic engine damage. The failure is silent and gives no prior warning.

• Sudden catastrophic engine failure with no prior warning (belt shed event)
• Loud mechanical bang followed by immediate engine stall
• No compression on multiple cylinders after failure
• Timing belt cover showing rubber debris or shredded belt material
• Engine cranks but will not start after over-rev or sustained high-speed run

Ask for full service history showing the cambelt was replaced with a complete OEM or quality aftermarket belt kit — verify the invoice specifies the balance shaft belt was also replaced, not just the main cambelt. Be extremely wary of any 6G74 with unknown belt history or mileage over 100,000 km without documented belt service. Have a mechanic remove the timing cover to inspect belt condition before purchase.

Parts involved: Timing belt.

$8,000 to $20,000 at New Zealand independent workshop rates. That is for this job on its own, not for the car.

An estimate, in NZD, 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.

• “Do you have a workshop invoice confirming both the main cambelt and the inner balance shaft belt were replaced, and when?”
• “What is the current mileage and when was the last timing belt service performed?”
• “Has the engine ever been rebuilt or replaced due to a belt failure?”

The failure described above is documented in published sources — owner forums, technical service bulletins, recall notices and workshop write-ups — held in our fault database. The inspection instructions and the cost estimate are KickTyres’ own interpretation of them, and it is a starting point for an inspection rather than a manufacturer statement.