I had posted a question a few months ago on how to stop my jeep from whistling when I let off the gas, but its a long thread. i gave up on solving the problem and had checked every suggestion but to no avail. I recently had a friend who has a mechanics stethoscope. Its been in several shops who can't find it and it took me several months to track down the noise, because it is intermittent and stops after a few minutes of idling. The noise is coming from around my compressor, within an inch or two, so could it be the pulley, compressor clutch, or a bearing. what should i check first? Any one experience this. i'll try to find my old thread if i can. thank you much.
Have you pulled the belt off and started it just for a minute or so to see if it is one of the item the belt turns??? Could be the alternator bearing,could be the A/C compressor,could be an idler pulley.I would start by pulling the belt after the engine has been off for a few hours then start for just a minute or two to see if that is what it is.If the noise it gone then shut it off an spin each pulley by hand to see if you can hear anything.
No i have not taken the belt off to specifically check the pulleys, but a local shop has had it in twice and said that there was no problem with the pulleys. Worth checking on my own though. I've had this problem for several months and now i finally have pinpointed the noise directly within inches of the compressor using a mechanics stethoscope. The jeep shops all said its a vacum leak but we can't find it. It is an ear splitting frequency and nothing changes the noise except pressing on the gas pedal.
Surfcape - Try tightening up up the intake manifold where it connects to the engine (Don't forget the bolts underneath). Mine did the exact same thing and took several hours to find that the engine was sucking air in between the engine and the intake manifold....horrible squealing noise that went away when you press the gas and came back at idle. Try that and let us know.
Sweet, thanks man. It has been a long problem. On page two of this forum is the other things that I have tried and that were suggested, I thought that it could have been the injectors or bearings in the pulleys, but the something is telling me that even though it sounds like the noise if from the compressor its my intake manifold because it bolts down so close. Just ran out at lunch to look find what i should check at my break, but was wondering how to access the bolts under the manifold without removing everything.
I used a 1/2 inch rachet with different extensions from underneath the Jeep (on a creaper). It takes a bit of patience, but you can get it from underneath with the right tools. Make sure you check all of the intake manifold bolts...some are hiding. Let me know how you make out!
The determining factor that made me finially realize it was the intake manifold was when I pushed down on the top of the air box (directly above the intake manifold connected to the throttle body)(while running) and the squeal changed it pitch.
Since I tightened the intake manifold up I no longer have any squeal, my Idle dropped (it was a bit high) and my gas mileage has improved.