99 C230 Kompressor Noise
 

I have been experiencing a noise which I describe as a "diesel knock" even though the car is not diesel. When slightly accelerating the noise begans, goes away at a slightly higher speed and returns at very low speed. Twice I have taken the car to the dealership for inspection and both times they tell me this noise is just the way a kompressor is. They tell me I will hear the rattling, clunking noise when the kompressor clutch engages and disengages.

Has anyone had the same experience and is there anything that can be done about this?

I appreciate your time and feedback.

The drive belt tensioners on the M111 engine has been a problem since 1996, the latest tensioner requires ADDING a belt shock absorber to dampen the noise (knock).

Thank you for your reply. Do you know anywhere on the web, or anywhere for that matter, that I can read about this? I would like to educate myself before talking to the dealership service advisor again.

clunking noise
 

Do you also hear the noise if you do braking from a high RPM?? I don't know if this noise is related to komprssor disengage or not, but I test drove a komprssor the other day and it had the same noise. The other problem has bothered me is the startup. Seems that superunlead feul will cause problems and once I switch to 89 octane feul, it will be fine.