Hi all,
I have an '89 300E with 150k mi that sqeals all the time now. I first noticed it back in febuary on a warm day, now it's constant. I don't think it's the serpentine belt because I just recently replaced it along with a new tensioner. I am also having some cooling issues wich I suspect is the cooling fan clutch. (the car runs hot, +100, when idleing,or in stop and go traffic for more that a few mins). As far as maintainance goes I don't know what the PO has done, but for the last year I've changed all the fluids.

Thanks.

I forgot to add,
I know it's coming from one of the serpentine accesories. I'm just having a tough time locating the sound. Any tips?

Try squirting a little oil on each of the bearings for pulleys driven by the belt. If you find one that quiets down with a little oil, that's the bad one. Most likely, it needs replacing, not just lubing.

If it's more like a growling than a squealing, do it soon!

__________________
Norm in NJ
Next oil change at 230,000miles

I experienced a similar problem and it ended up to be coming from the alternator pulley. I was able to purchase a new aftermarket pulley for about $40. By the way, the local MB dealer would only offer a complete alternator at $400.

Go to your local auto parts store and buy a $10 stethoscope.
Run the engine and carefully place the probe on each accessory.
You will hear the culprit.

Steve