Fan belt symptoms

Fan belts, or alternator drive belts, transfer power to several important parts of the car including air conditioning, power steering and the alternator, according to These belts do deteriorate with time and use, however, and eventually may break.

This can cause a loss of power or even more serious damage, so it is important to be able to identify the symptoms of a faulty fan belt and to replace or realign it before it fails. There are several common symptoms to look and listen for.

Unusual Sounds

The most common audible clue of trouble is a loud screeching noise. You may hear this sound just after you start your car, when manoeuvring slowly, or after driving through an especially deep puddle. It is a symptom of a loose fan belt, and the longer you hear this screeching sound, the worse condition your fan belt is in. Another potential indicator of a failing fan belt is any rhythmic sound when you are driving. This sound may indicate something embedded in your fan belt. Less common sounds indicative of a failing or incorrectly aligned fan belt include hissing, rumbling, grinding and rattling. You will need to replace or adjust a belt that exhibits any of these symptoms to avoid eventual loss of power to other parts of your car, and possible engine damage.

Dimming Headlights

You may notice your headlights dimming when the belt is working overly hard to turn the alternator and recharge the battery after starting the car, or when you are placing a heavy load on the power steering by turning at low speeds. This symptom is more common on diesel cars than gas-powered vehicles.

A Tattered Appearance

Most fan belts in modern cars are serpentine belts and have to snake round a number of different pulleys. This causes the belt to heat up and then harden, which, over time, may cause any number of imperfections in the belt, leading eventually to belt failure. Examine your fan belt for any signs of cracking or fraying. It needs to be replaced immediately if it exhibits these symptoms. Chunking (when parts of the belt have ripped out) also indicates a serious problem. In addition, look carefully for any signs of uneven wear, abrasion, rib separation and gravel penetration. These may be signs of the need to replace or realign. Any contamination with fluids means that the belt may be attracting dirt, which is a problem in itself but also indicates a potentially larger problem with either oil, power steering or coolant leakage.