Hi,

You are describing the auxiliary belt that drives the alternator and powersteering (if fitted). This needs to be replaced or it is likely to snap and leave you stranded somewhere.

As far as I am aware this model year Fiesta has no adjustment on the alternator to allow the belt to be fitted. It is an automatic spring loaded tensioner system.

You have to put a spanner on the centre nut of the tensioner pulley and then rotate it clockwise (as if you're tightening the bolt). This pushes the tensioner back against its spring pressure, and lets the belt be slipped of the pulleys.

The belt itself is cheap. Also, any mechanic will fit it for you for at a cheap rate as it only takes a few minutes. There may also be a problem with one of the auxiliaries that it is turning so if you are not familiar with cars it might be best to get a mechanic to check it to make sure there is not one of these auxiliaries causing the problem in the first place.

Alternatively - If you are happy to do so you can change the belt first yourself and see if the noise stops. These belts are a common wear issue.

Thanks for using FixYa. If this has helped please do take a moment to rate the solution.

It will be necessary to replace the belt before it breaks and leaves you stranded. Good Luck! I hope you find this to be very helpful!