Hi all, just registered. I just real recently acquired a used 2007 c230 Sport Sedan, and I've just hit 119k yesterday or so.
Anyways, I've been noticing some type of grinding sound (not real harsh, but noticeable). It seems to happen with lower speeds, as in.. ~5-30 mph or something, and perhaps with RPMs under 3k.
I'm not sure, but it may not seem to happen after the car has been driven for a while (warmed/heated up?). And I also have maybe not noticed it while driving faster such as highway speed(s). It seems to come from the front of the car under the hood or so? I don't think turning while driving has any noticeable affect to where it happens.
It's a slight grinding kind of sound, and it doesn't seem constant like "grrrrrrrr", but more like "grrr gr gr" (intermittent?)
Edit: The sound might not happen while the car is in idle or parked either though, but I'm not sure about if I rev it while parked.
Edit: Listen to a recording I did, it's not as loud on the recording maybe, but..
Anyways, pay special attention at 5 or so seconds, try to listen for like a grinding noise.
Edit: Not that whining sound, but the like grinding noise...