Hi everyone,
Yesterday I replaced one of the three rubber air filter housing mounts, and relocated my boost gauge from near the right knee of the driver, to above the left air vent, next to the instrument cluster. This morning when I pulled the car out to drive it, I heard this really pretty loud chirping sound coming from somewhere in the engine bay. I can't decide where, somewhere around the passenger side, possibly near the air filter or near the belts. I drove for about 80 miles and noticed no change when I came back home.

There used to be a sound of loose marbles coming from the air filter, but that has gone away probably because of the housing mount replacement.

Also, when I tap the throttle, not hard, if I touch it at all, the chirping goes away. I really have no idea what this could be and it didn't really affect the driveability of the car. I fixed that filter housing mount because I was looking forward to a nice normal sounding idle, and now this. Are there any typical causes of this? Slipping belt? I applied some belt dressing which didn't seem to do anything. Thanks for the help

Alex

Alex, I have had the same sound off and on in my 300D. Try this, wht the engine idling, place your hand on the air cleaner, press down and see if the sound goes away. When I have a air cleaner mount broken the air cleaner rubs against the a braket next to the vaulve cover causing the chirp. (goes away at anything over idle speed)

Look at your other air cleaner mounts and see if one or more are not still in need of replacement. I usually replace all three at the same time. Hope this helps.

Yes Yes!!! That is exactly what it sounds like. When I put pressure down on the air filter housing near the intake tube, the sound goes away. The other two mounts looked ok, but I will order two new ones and replace them anyway. For a few bucks, why not. Thanks so much. I was worried it might be something like worn bearings in a pulley (although that seemed somewhat unlikely because the sound goes away above idle).

Alex