I have an engine noise that I am not sure of... It is a squeal like a fan-belt noise and it only happens when I let off of the gas. When the engine is accelerating (loaded), the squeal stops. It is not the alternator belt and the air pump is as tight as I can get it. I can't locate the source. The noise is there if the clutch is engaged OR dis-engaged, at idle or moving... but only when I let off the gas.