Timing belt or timing chain: which does your car have?

The quickest way to find out is to look up your exact engine in the handbook or service schedule, because the answer depends on the make, model, engine size and sometimes the year. A belt is a toothed rubber band with a replacement interval. A chain is metal, runs inside the engine in oil and usually has no fixed interval.

That difference matters because a belt that snaps can wreck an engine, while a chain tends to give warning noises first. Below we explain how to tell them apart, what to listen for and what a garage checks.

How do I find out if my car has a timing belt or chain?

Start with the owner's handbook. The service schedule will list a belt change at a mileage or age, or it will say nothing at all if the engine has a chain. If the handbook is missing, your registration number and engine code give a garage what it needs to look the engine up.

Looking at the engine is less reliable than people expect. A belt is normally hidden behind plastic covers at the side of the engine, and a chain sits behind a metal or alloy cover bolted on and sealed with oil. A cover alone does not tell you which you have.

• Check the handbook service schedule for a belt interval
• Note the engine code on the V5C or under the bonnet
• Ask a garage to look it up from your registration
• Remember that two engines in one model range can differ

Is a cambelt the same thing as a timing belt?

Yes. Cambelt, timing belt and sometimes drive belt for the timing are all the same part in everyday use. It links the crankshaft to the camshaft or camshafts so the valves open and close at the right moment for each piston.

Do not confuse it with the auxiliary belt, which you can often see at the front of the engine driving the alternator and other parts. That belt is a separate job with a separate lifespan.

Do timing chains ever need replacing?

A chain is built to last, and many are never touched in normal ownership. They are not for ever, though. Chains stretch, and the guides and tensioners that hold them in line wear, especially if oil changes have been missed or the oil has been left to get dirty.

Common warnings include a rattle on a cold start that fades as the engine warms, a rattle that stays, a warning light, or rough running. Treat these as a reason to have it looked at promptly rather than waiting to see.

What happens if a timing belt breaks?

On many engines the valves and pistons can meet if the timing is lost, which is why the damage can be severe. Whether yours is one of those depends on the engine design, so do not assume either way.

If a belt is overdue or you do not know its history, it is worth having it checked. If you buy a second-hand vehicle with no record of a belt change, treat the belt as unknown and ask a garage to advise before relying on it for long journeys.

What does a garage do about a belt or chain?

For a belt, a garage normally replaces it together with the tensioner and idler parts that run with it, and often the water pump if the belt drives it. That is why the work cost depends on the engine layout, how much has to come off to reach it and which extra parts are due.

For a chain, we start with diagnosis: listening, scanning for fault codes and checking the oil condition before suggesting anything. At Automaster, a garage at Longcombe Cross near Totnes, we cannot promise a repair until the car has been inspected.