The fan belt is a flexible synthetic rubber band which connects various engine components together.
It has a long series of teeth running along the inner surface of the belt which generate traction, allowing it to grip to the shafts it connects and keeping it from slipping off at any point. The fan belt is used to transfer rotational power from one place to another in the engine.
It works in a very similar way to the timing belt; the only real difference is that it connects a different set of rotating shafts together. It is called the fan belt because one of the shafts which it connects to is the spinning engine cooling fan.
If you can hear a belt squeaking whenever the engine on your vehicle is switched on then it is likely to be a problem with the fan belt. As it wears thinner, the texture of the fan belt changes to cause a loud squeaking as it makes contact with engine shafts. This is a clear sign that you need to have your fan belt replaced. It is a procedure which you can do yourself, but it will take a couple of hours and can be a fiddly process depending on the make and model of your vehicle.
A good quality fan belt will be designed to minimize the amount of friction generated within your car’s engine. Newer fan belts are made with curved teeth exactly for this purpose.
Decreased friction in the engine will increase the overall performance of your engine. It will also mean that the belt will last longer and will have to be replaced less often. If you are worried that your fan belt may be wearing out then you should take your vehicle in to be checked over by a professional. They will let you know the condition of your fan belt and whether you should have it changed immediately.