V-Belt Squeal....Only When Slowing Down

[placo1]

I need some help with this before bringing my car in for it's service. When I was out on a drive yesterday I noticed my V-Belt was squealing but here is the weird part.........

1. It doesn't squeal when the car is started

2. It doesn't squeal when the car accelerates (Doesn't matter how hard)

3. It doesn't squeal when I turn the steering wheel (no power steering pump issue)

But it does squeal after I have accelerated very hard and completely let off the gas! What could cause this? Do I need a new V-Belt or are one of the components damages....possibly the tensioner?

I would really appreciate any experience on this. The car is a 92 500E.

Thanks everyone.