Intermittent whine from transmission area
 

I have a 2009 C220 cdi Sport with 5 speed auto transmission. Recently I've been getting an irritating whine from the transmission area. Its only there at certain engine speeds in each auto gear ratio, but of course its always present when driving at the various posted speed limits!

The strange thing is that the noise is sometimes there when the car is stationary, at a traffic light for instance. Is there anything that could be causing this that is always turning in the transmission, irrespective of being stationary or moving? Driving me crazy. Dealer says there's nothing wrong (don't they always?) but it hasn't always been there, only recently. Car has done 67,000 miles from new in my hands and is scrupulously serviced by main dealer at the posted intervals, since then.

Any help or advice greatly appreciated :nix:.

I have a 2007 model with 5 speed auto. I also thought I had a atm whine initially but I found it to be coming from the air conditioner when lightly loaded ie a cool day.The A/c works fine.

It sounded rev related & changed tone with the gears changing ( revs).It sounds to be a gas or liquid throttling sound.

It does not happen with the A/C off.

I did not get whine at all the different situations that you did such as while being stationary, but I did get it while at speeds between 20 to 60+ and it was a failed transmission on the 2010 at 44k miles and trans was serviced at 35k.

Intermittent whine
 

"Quote" I have a 2007 model with 5 speed auto. I also thought I had a atm whine initially but I found it to be coming from the air conditioner when lightly loaded ie a cool day.The A/c works fine.

It sounded rev related & changed tone with the gears changing ( revs).It sounds to be a gas or liquid throttling sound.

Thanks for the update on your issue. I'll certainly check that out. :bow:Did you get the A/C whine fixed? Mine is also working fine (doesn't usually get that challenged here!).


"Quote"
I did not get whine at all the different situations that you did such as while being stationary, but I did get it while at speeds between 20 to 60+ and it was a failed transmission on the 2010 at 44k miles and trans was serviced at 35k.

Thanks for your input. Hope mine isn't going to be the same. Think yours would be a 7 speed trans though. Did you get any other indication it was going to fail? :bow:

No , it has been there for years , I just make the setting colder & it stops.

Experts say a re-gassing may fix it. I am not sure as it is very efficient.