chirping sound on cold start
 

I am experiencing a light chirping sound when I start my e420 from cold engine. It is light in intensity and goes away after a few minutes. Any ideas as to what may be going on or getting ready to go on..
Thanks!

just bringing this one back to the top..does anyone have any ideas?

Perhaps the accessory belt? It might be glazed. Is this belt original?... then it may have stretched to the limit of the tensioner and should be replaced, even if it looks good.

I'm wrestling with the same problem on my Marquis and it needs to be checked out.

Check your air pump, belt. Air pump is activated in cold start.

mine was belt tensioner
 

I had similar problem few years ago and it was the belt tensioner

This is really timely for me. I've noticed a chirping coming from the left side of the engine lately which goes away after a couple minutes. Sure seems to be coming from the belt tensioner, but I figured it wouldn't go away if it were the tensioner.

Sure is a better ($) alternative than the AIR pump!

The chirping on my Marquis also goes away after a few minutes. I'm convinced it has to do with the cold weather. Belt loads are highest when the car is cold.... ps fluid is thickest, coolant has a somewhat higher viscosity, belt is least sticky. So if there is any weakness in the system, it'll show up on a cold start.

What puzzles me on my problem is the belt was replaced 3 yrs/16,000 miles ago.... too soon for belt replacement.

I figure only two things can go wrong with a tensioner -- the spring breaks or the bearing gives out. The spring should be easy to check. A bad bearing should squeal constantly -- right?

One thing I do whenever the belt is removed is that I clean the pulley grooves in a serpentine system. I notice a lot of crud gets built up in the grooves. I imagine it can push up on the belt and prevent full-grip engagement.