loud squeal coming from engine please help

[jsumney]

I have a 1997 BMW 318i with 138500 miles I just bought this car and have already put a new thermostat, serpentine belt, A/C belt belt tensioner, and idler pulley and still there is still a loud squeal after about 25 minutes of driving. the squeal goes away on acceleration, but as soon as I take my foot off the gas( either coasting down a grade or sitting at a stop light) the squeal comes back. I am at my wits end I hope someone can help thanks.

[Manolito]

Are you sure that it is not a whistle (vacuum leak).

Hard to imagine a squeal that goes away on acceleration but comes back with deceleration.

Vacuum, on the other hand, increases with deceleration, so a leak would whistle louder.

Does the car idle smooth? If not, spray some starter fluid around the intake manifold and see if that smooths it out as the fluid gets sucked in through the leak.

[Jared at Pelican Parts]

Did you turn all of the pulleys when the belt was off? This could be a bad water pump, power steering pump, etc..

[jsumney]

I found the source of the noise, and jerry rigged it. It was a vacuum leak at the pcv valve. what I did was made a rubber gasket for under the pcv valve to block off the vacuum leak and left the breather hose disconnected to vent off crank case gasses. Car runs smooth no noises. thanks for the replies, this is my first imported car so i will more than likely be asking some more stupid questions in the days to come. thanks again