Chirp/Squeak Where is it coming from?

[davestx]

I have been hearing an intermittent chirp/squeak from my 1991 Mercedes 420 SEL with 560 motor for over a year. It is getting worse now but It still is not consistent and never happens when the car is stopped. It only happens at speeds of 45MPH and up. At first I thought it was the heater blower but it is not. It only happens for a few seconds at a time. Belts were just replaced. any troubleshooting advice?

[MDE3]

failing belt tensioner

[davestx]

Thanks. I will have my mechanic check.

[davestx]

Did you mean the A/C idler pulley. If so, that was replaced.

[John5788]

for me it is the belt tensioner. I /just/ finished replacing it an hour ago. same symptoms

I have noticed on this car of mine I recently purchased it makes a squeaking or mousey sound intermittenly. To my hearing it acts like it's by the driver's side door, but thats just a guess. It's almost like it is a timed sequence. Is this possibly the same as you are in reference to?

[Randy]

Rebe's issue seems to describe the bottom of the door trim rubbing on the plastic door sill covers. This can be caused by a slight tire imbalance and so seem mechanical. This is well-known W126 trait and has been discussed elsewhere in this Forum; try a search.
Other sources of squeaks include accessory belts, worn pulleys, front sway bar bushings, basically anything that moves can be a potential source of a squeak.

[davestx]

Thanks for your replies. I replaced all of the belts and the A/C idler pulley. It seems to be sensitive to the throttle. When I give it more or less it seems to stop the sound. It does sound mechanical like a screeching pulley but it never happens when the car is stationary which is making it hard to track down.

I searched the threads and found some info on the door sills etc. that can cause squaking. I will try some of the remedies and maybe resolve the squeaking noise. It is not that disturbing, but you can definitely hear is happening.