I have searched the forums for a while, and all I can find are people with "ticking" noises under the hood. I have what sounds like a whinning sound that is comming from some rotating piece on the engine as it increases pitch with engine speed. I'm assuming it's from a pully bearing, but which one? I've heard many mercedes engines that make the same noise, but it's getting kinda loud. I have a 05, manual NA with 48,000 miles. Has anyone else had a similar problem? Any helpful advice?

 

you know I have that noise myself. It comes from the alt. it is a high output alt. if it gets to noisy you need to have it checked. I am a tech. and have checked mine and it seems fine for now but you never know.

 

Problem solved, it was the idler pully. THe bearing was shot so the pully was loose and making the odd noise. The part was $32 from Mercedes, and it took 15 minutes to replace. Now the engine purrs like it did the day I took it home from the dealer (with the exception of the exhaust, which sounds more prominant now that the engine is quieter)