Fan Belt and FEAD systems
It has long since passed into motoring folklore that a broken fan belt could be replaced temporarily by a pair of women’s tights, wrapped judiciousy around the engine pulleys as a get-you-home device. This would not work on modern, multi-ribbed pulleys, as it could even cause severe engine damage. Like many parts of a motorcar, not only has the fan belt become more sophisticated but its associated components have too.
The old-style fan belts used to drive relatively few parts. These days, an increasing number of ancillary components rely on the belt to transmit power to them from the crankshaft pulley. As the belt drive has become longer, tensioners, idler pulleys and even ‘flexible’ alternator pulleys have been introduced. The belt alone, therefore, is no longer considered to be a separate component but, rather, part of a kit of parts called the Front End Auxiliary Drive, or ‘FEAD’ system.
An advantage of all this complication is that the fan belt (or, in modern parlance, the ‘auxiliary’ belt) can last for over a decade and around 80,000 miles. The problem is that, when the belt requires renewal, all components that comprise the FEAD system should be replaced as well; something that will increase both the labour and parts bills. Pictured is a typical FEAD system, comprising of a belt, automatic tensioner and an alternator pulley. Obviously, each car model will have its own requirements.
When to change
In cases where your car manufacturer specifies that the FEAD system be serviced, that interval must be prioritised. Otherwise, work should be performed whenever the timing belt and its associated components are renewed. Should your car not possess a timing belt, the general advice is to have the FEAD system checked at c.60,000 miles and replace it at c.90,000 miles.