I own a 2001 MBZ E320. I am getting noise coming from what I thought was my idler pulley, so I pulled the serpentine belt and ran the engine. The noise went away and I found the idler pulley's bearings were bad and replaced the pulley. I checked the remaining pulleys and all appeared well. I reinstalled the belt and the noise returned. I re-checked the pulleys and found some "play" in the pulley attached to the waterpump. Does this "play" mean the water pump and pulley need replacement? It should also be noted I don't see any leaking or heating issues with the colling system.

From your description it seems that the water pump is failing. What is the mileage on your 2001 E320? If the water pump is original, recommend replacing it before it self-destructs and you get stranded somewhere.

__________________
Fred Hoelzle

My car has 126000 miles and I bought the car used so I don't know if it's an original part. I will replace the water pump. Thanks!

just replaced 1 on a crossfire with 40k on it. it was blocks from falling apart. was rubbing against the cover but the owner didn't hear it. good luck, chuck.