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Cam belts also known as a Timing belt - The essential Q&A guide

Updated: Jul 2, 2023

VW TDI Engine timing belt or cam belt
New Genuine VW Timing belt kit

What is a cam belt or Timing belt?

A Cam belt also known as the timing belt is a vital component of your engines mechanical working.

The cam belt is made up of sturdy composites like Kevlar and polyurethane, it has strong teeth on it that’s designed to keep the camshaft and crankshaft in time.

What does a cam belt or Timing belt do?

It's primary job is to connect the top of your engine to the bottom, so when the crankshaft turns, the belt then turns the camshaft or camshafts at the precise same time, which refers to the alternative name as a Timing belt as it keeps the engine in time and in sequence of when the valves to the cylinders open and close.

The engine's camshaft or camshafts open and close the valves that let air and fuel in and out of the cylinders to be combusted and exhausted.

The crankshaft moves the pistons up and down in the cylinders.

These two functions MUST happen at the precise same time or contact within the engine can be catastrophic.

The belt commonly also drives the water or coolant pump.

When do you replace a cambelt?

This will depend on your make and model of vehicle, This is usually recommended by the manufacturer on mileage or time (years) whichever comes soonest.

The best way to be sure is to check your service or handbook. Alternatively you can give us a shout and we can check the interval for you.

Reasons for cam or timing belt failure?

The most common reason for failure is due to lack of maintenance i.e. The belt not being changed at the manufacturer recommended interval.

The belt becomes brittle over time causing it to crack and fray eventually it will break or snap.

Other causes could be that the belt gets contaminated with for example oil/fuel or engine coolant. if you have a leak of any kind coming from your engine you should get this rectified asap before it could cause premature failure to the belt.

Some engines have what's called a 'wet belt'. This usually runs within the engines casings and runs in with the oil. Possible premature failure of these types of belt are commonly down to poor engine oil quality, not having regular oil changes or routine maintenance.

How to prevent cambelt failure

The moral of the story is to keep to, or stay on the safe side of your manufacturers recommended service interval. Unfortunately cambelts and there tensioners and idlers are mechanical moving parts so can in worse case scenarios' fail prematurely, you will have no control over this but it's extremely rare.

If you have no evidence or history that the belt has been changed within the time or mileage then get it checked or better still changed anyway. cost for this will be far less than a destroyed engine!

Useful links and tools to carry out a cambelt change on a Volkswagen Group vehicle

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