The timing belt (or cambelt) keeps the engine’s crankshaft and camshafts turning in perfect sync, so the valves open and close at the right moment. It is hidden inside the engine and gives little warning before it fails.
On many engines, a snapped belt means the pistons hit the valves, causing major damage.
Belt or chain?
Some engines use a metal timing chain instead of a rubber belt. Chains are designed to last much longer, often the life of the engine, though they can stretch. Your owner’s manual or a garage can tell you which your car has.
When to replace it
Manufacturers set an interval by both mileage and age — commonly somewhere between 60,000 and 100,000 miles, or every five to ten years, whichever comes first. Age matters because rubber degrades even if the car is rarely driven.
Buying a used car
If you are buying a used car near or past the interval, ask for proof the belt has been replaced. If there is none, budget for it straight away. It is a common reason for an older car being cheaper than it looks.
What the job includes
- ▸The belt itself
- ▸Tensioner and idler pulleys, which wear at a similar rate
- ▸Often the water pump, if it is driven by the timing belt
- ▸Labour, which is usually the largest part of the cost
Warning signs
Belts rarely give warning, but a ticking from the front of the engine, difficulty starting, or misfires can sometimes point to a worn belt or tensioner. Do not wait for symptoms — stick to the schedule.
CAUTION: This is general automotive information, not professional mechanical advice. Always follow your vehicle manufacturer’s specifications and service schedule, and have brakes, steering, tyres, and other safety-critical systems inspected by a qualified mechanic.