Questionmy sons car has a rattle, when looking under the bonnet the fan belt was "jumping" when the engine was ticking over, what could be causing this? if it needs tightening how do we do it?
AnswerThe alternator has two sets of bolts, one is a hinge one is a clamp, loosen the "hinge" first, then loosen the clamp - you can now move the alternator on the hinge and tighten the belt, hold the alternator with a little force so the belt is taught and tighten the clamp, then retighten the "hinge".
When a belt becomes loose like this it is either because the belt is worn, has started slipping then overheated and stretched - or the car has gone over a hard bump and dislodged the alternator.
If the belt looks tatty is cracked or perished it's best to replace it, but tightening an old worn belt is ok for a temporary solution until you can source a new fanbelt.
