A timing belt, also called a cambelt, should be replaced at the interval your manufacturer sets, whichever comes first, time or mileage. For many cars that is somewhere between 40,000 and 100,000 miles, or four to six years, but some are longer. If it snaps, many engines are damaged badly enough to need a rebuild or a replacement.
The reason it matters is that a belt rarely gives much warning. You change it by the book, not when you hear something.
What it does
The timing belt keeps the crankshaft and the camshaft in step, so the valves open and close at the right moment for the pistons. It is a rubber belt with teeth, and it wears and ages like any rubber part.
What happens if it breaks
In many modern engines, known as interference engines, the valves and pistons move through the same space at different times. If the belt snaps, the pistons can hit the open valves. The result is bent valves, damaged pistons and sometimes more.
In a non-interference engine the car simply stops, which is less costly but still leaves you stranded. Your handbook or a garage can tell you which type you have.
Belt or chain?
Some engines have a timing chain instead of a belt. Chains do not usually have a set replacement interval, but they are lubricated by the engine oil, so they suffer when oil changes are missed. A chain that is stretching can rattle or rattle at start-up, and it needs attention. A belt is replaced by the schedule, and a chain is looked after by good servicing.
Replace the water pump at the same time
On many engines the belt also drives the water pump. The labour is most of the cost, so replacing the pump and the tensioners in the same job usually makes sense. We will tell you what your engine needs, and why.
How to find out when yours is due
- Look in the handbook or the service schedule for the cambelt interval, in years and miles.
- Check the service history to see if it has already been done, and when.
- If you have bought the car used and there is no record, assume it has not been done and ask a garage to check.
- Book it ahead of the date, not after.
Tell us the registration when you book online, and we will look up what your car needs. Timing belts are part of our repairs.
Quick answers
How often should a timing belt be changed?
At the manufacturer's interval, by time or mileage, whichever is first. Many fall between 40,000 and 100,000 miles, or four to six years.
What are the signs a timing belt is failing?
Often there are none. Some cars give a ticking or whining noise, but the safe approach is to follow the schedule.
Does the MOT check the timing belt?
No. The MOT does not check the engine, so it will not tell you when the belt is due.
Can I drive on a belt that is past its date?
It is a gamble. The belt may be fine, or it may not, and the cost of losing is an engine.