Guys

Alternator belt on the Mondeo is squealing at idle (albeit quietly) but quietens as soon as the engine is under load so I guess it needs replacing (have already squirted some GT85 on it and whilst it quietens it for a bit it soon starts again). The belt itself is pennies but the tensioner is monster money, Ford having quoted me £153.73. I'm going to get the belt changed, but is it necessary to replace the tensioner at the same time as well ? I don't want to spend £150 on a tensioner if I don't really need one !

Help !