the same thing happened to my non-Mercedes 4 cylinder car today. I started it up and it sounded like ****. So I popped the hood and looked around and I had found a tube had popped off a cylinder looking thing with many hoses attached to it. I think it popped off because I was redlining up my hill where I live. Gotta love Japanese engineering. As far as your C220, check if any hoses have popped off or if you here a hissing noise indicative of a vacuum leak. If you cant figure it out yourself then I would recommend taking it to the mechanic because I think the transmission pump is vaccum powered (dont quote me) and you dont want to have domino problems