When Should You Change Your Timing Belt?

What a timing belt does

Inside your engine, the crankshaft turns as the pistons go up and down, and the camshafts open and close the valves. The timing belt links the two, so every valve opens at exactly the right moment for every piston.

It is a toothed rubber belt, reinforced inside, and it lives behind a cover at the side of the engine. Because it is rubber, it wears with age and use, which is why manufacturers give it a set change interval. Not every car has one. Some engines use a metal timing chain instead, which is meant to last much longer.

If you are not sure whether your car has a belt or a chain, your handbook will say, or you can give us a ring with your registration and we will tell you.

How often it needs changing

There is no single answer. Each manufacturer sets its own interval, usually given as a mileage and a number of years, whichever comes first. Depending on the engine, that can be anywhere from around 40,000 miles to over 100,000 miles, and from about four years to ten.

The years part catches a lot of people out. A car that only does short trips around Pelsall may never reach the mileage, but the rubber still ages. If your car is past the time limit, the belt is due, however few miles it has done.

Your service book should show when it was last done. If there is no record of it, we treat it as unknown and usually advise changing it, because there is no way to see the age of a belt by looking at it.

What happens if it snaps

When a timing belt breaks, the engine stops straight away and the car will not restart. On many engines, known as interference engines, the pistons and valves share the same space at different moments. Without the belt keeping them in step, the pistons can hit the open valves.

That can bend valves and damage the pistons and cylinder head. The repair can cost far more than the belt change would have, and on an older car it can be the end of the engine. That is why we always say a belt change is cheaper done early than late.

Warning signs are rare

Unlike brakes or a clutch, a timing belt usually gives little or no warning before it goes. You may occasionally hear a whine or rattle from a worn tensioner or pulley, or see cracking if the cover is off, but most belts look fine right up until they fail.

An oil or coolant leak onto the belt can shorten its life too, so if we spot a leak near the timing covers during a service, we will tell you.

So do not wait for a symptom. Go by the interval in your service schedule, and if you have just bought a used car with no proof the belt has been changed, get it looked at soon.

What we replace

When we change a timing belt we normally fit a kit, which includes the tensioner and idler pulleys as well as the belt. These parts wear at the same rate, and a seized pulley can wreck a brand new belt.

On many engines the water pump is driven by the timing belt and sits behind the same covers. If yours is one of them, we will usually suggest changing it at the same time, because most of the labour is already done. We will always explain what your engine needs and give you a quote before any work starts.

Book it in with us

Mark has been in the motor trade for more than 30 years and has changed a lot of timing belts in that time. We will check your service history, tell you whether the belt is due, and give you a clear price.

Call us on 01922 682200 or book online, and we will look after it at our garage on Pelsall High Street.