What are the signs your cambelt needs changing?

Many cambelts fail with no noise, no warning light and no change in how the car drives. For that reason the main sign that a cambelt needs changing is that it has reached the age or mileage the manufacturer gives for your engine. Look for it in the handbook or service book, because it varies by vehicle.

There are some physical symptoms that can point to a belt or its related parts. They are worth knowing, but do not wait for them before acting.

When should a cambelt be changed?

Manufacturers usually set a limit of both mileage and age, and whichever comes first applies. A car that does few miles can still be due because rubber ages. The figures differ widely between engines, so check your handbook or ask a garage to look it up from your registration.

If you have bought a car and there is no proof of a belt change, it is sensible to treat the belt as overdue until a garage says otherwise.

Is a ticking or squealing noise from the engine a cambelt problem?

It can be, but it is just as likely to be something else. A squeal at the front of the engine is often the auxiliary belt rather than the timing belt. A rhythmic ticking can come from the valve gear or from a worn pulley or tensioner.

Because the cause is not obvious by ear, the noise should be investigated rather than guessed at. A garage can listen, look for play and check what the belt drive is doing.

What can you check safely at home?

You cannot see the timing belt itself without removing covers, so do not try to prise them off. What you can do is look for signs around the engine and gather paperwork.

Keep the car off the road if anything below suggests the engine is struggling to keep time, and have it looked at first.

• Look under the car and around the engine for fresh oil or coolant leaks
• Find the service history and any invoice showing a belt change
• Note any new rattle, squeal or rough idle and when it happens
• Check for warning lights on the dashboard
• Read your handbook for the stated interval

Should I keep driving if I think the cambelt is failing?

No. If the engine suddenly runs roughly, misfires badly, struggles to start, or you hear a new ticking or grinding from the belt end, stop somewhere safe and do not keep restarting it. If the belt has broken, repeated attempts can add to the damage on many engines.

If you are only worried because the belt is overdue and there are no symptoms, short careful use to reach a garage is a judgement call. It is safer to ask for advice first than to carry on for months.

What does a garage do when a cambelt is changed?

The belt is normally replaced with the tensioner and idler pulleys, and the water pump too where the belt drives it, since they are accessed during the same job and wear at a similar rate. A garage also checks for oil leaks from the seals nearby that could contaminate the new belt.

The cost depends on the engine layout, how much has to be removed for access and which extra parts are due. At Automaster, in Longcombe near Totnes, we can look at your car and give you a quote once we know the engine.