2006Merc

Happy new year all, I have a 2006 E350 4matic wagon, 192k miles. Last year the Merc developed a whining noise coming from the front of the engine. My troubleshooting started with a search of this forum and it appears that there are a lot of options to investigate. I found a video on youtube with a guy that had a C2320 with the same noise, he changed the alternator and the noise was gone. Several posts did the same with positive results. I replaced the alternator and the noise remained. I changed the tensioner, noise remained. I changed the power steering pump and reservoir, still whining. I changed the water pump, and two idler pulleys, still whining. The only rotating part left is the pulley on the A/C compressor. Does anyone know if it is possible to just change the pulley? The A/C works fine, I do not want to change the compressor if I can just change the pulley. I must add that when the serpentine belt is removed there is no noise.

801

Ding Ding Ding ... we have a winner. You guessed it ... AC compressor pulley bearing is what you're hearing. See (google) MB DTB S-B-83.55/87f which specifically addresses M272 engine AC pully whining. There's an updated pulley/bearing that can be installed. And yes ... compressor working perfectly even with the whining pulley is quite normal and common.