The cam belt (also called a timing belt) is one of the most important maintenance items on a car engine, and one of the most costly to ignore. Here is what you need to know.
What does a cam belt do
The cam belt connects the crankshaft to the camshaft (or camshafts), keeping the valve timing in perfect synchronisation with the pistons. If the belt snaps or skips, the valves and pistons collide. On most engines, this causes catastrophic internal damage: bent valves, cracked pistons, and a repair bill that often exceeds the value of the car.
Not all cars have cam belts
Some engines use a timing chain rather than a belt. Chains are generally longer-lasting than belts and often do not need scheduled replacement, though they can wear and stretch over high mileages. Check your handbook or ask your garage to confirm which your engine has.
When to replace a cam belt
Cam belt replacement intervals vary by manufacturer, typically between 4 and 6 years or between 40,000 and 80,000 miles, whichever comes first. The interval is usually listed in your vehicle handbook under the maintenance schedule. Common examples: Ford Fiesta and Focus petrol engines every 5 years or 62,500 miles; Volkswagen Group petrol engines often every 5 years or 75,000 miles; many diesel engines every 4 years or 60,000 miles.
These intervals are maximums, not suggestions. Exceeding them significantly increases the risk of belt failure.
What about used cars
If you buy a used car and cannot confirm when the cam belt was last changed, treat it as overdue and have it replaced. A cam belt and water pump kit (the water pump is usually replaced at the same time) typically costs between £250 and £500 + VAT depending on the engine. An engine rebuild after belt failure can cost £2,000 to £5,000 or more.
To check whether your cam belt is due, call us on 0131 554 3423 or get in touch here. We will look up the interval for your specific vehicle.