Whistling Noise

Hello,

I have a '95 Lumina 3.1L w/ ~150Kmi.
I always hear a whistling noise when driving between 1500-2500 RPM....seems to go away or become inaudible after 2500 RPM or so. It sounds like a vacuum leak but the car idles and runs great.

I recently replaced the upper & lower intake manifold gaskets (as part of another issue) and double checked all vacuum lines in the area and all seemed good.

I have not removed the belt and checked any accessories yet, but I suspect the water pump may be going out b/c a couple weeks back I noticed a very small amount of coolant thrown onto the lower radiator hose. It has since dried up and I have not seen any fresh coolant on the lower hose.

The alternator was replaced just over a year ago.

Can a water pump be the source of the whistling or vacuum leak type noise?

Any other ideas?

Thanks.

The other day I did some more listening and trying things out to see how it affected the whistling noise.

When the car is idling, at a stop, at normal operating temp, I noticed the sound can NOT be heard when the transmission is in gear for, R, D, OD, 2, or 1.

However, as soon as you shift into P or N, the sound becomes very audible.

This leads me to believe it is something to do w/ the tranny.

If it is the tranny, is it anything major?

The tranny was just rebuilt ~3K mi ago., but since this car sat for about 6 months, it is already past the 1yr. warranty.

Thanks.

Can anyone comment as to whether the symptoms I have listed so far may point to the vacuum modulator on the tranny?

Thanks.

well it could be a leak in it but if the car is shifting ok and not sticking in one gear it is doubtful try checking the rubber lines on each end of the pipe leading to the vacuum modulater possiblity that the rubber rotted out on each end or on end>?

Which trans does it have, 4t60-e, or 4t65-e?

I have the 4t60-e

Digging this one back up from me about +7 years ago...

Whistling noise ended up being the power brake booster. Just picked up the car today after a booster and master cylinder install and no more whistling noise that has been going on since I first got the car back in 2008.

Thanks for updating.