Hi, just asking a question for my mother She has had a fan belt replaced and it squeals like mad. The mechanic says he can't tighten it as it is a self adjustable belt. Is this right? The mechanic has told her to spray pledge(furniture polish) onto the belt to stop it I heard somwhere about hair spray. I also heard somwhere else not to put anything on the belt. Thanks

Merc 190e 1993
English model
2.0l
Only done 60,000 miles (genuine)
Warren