I've had this car, a 2005 E500 for 2 years and it's always made this whining noise that goes up and down with engine RPM. I've been reading all the other threads on this and it sounds like the transmission pump could be the culprit. I removed the serpentine belt, spun all the pulleys and they sound fine. Just for giggles, I started the engine, and sure enough the whine was still there, even with the drive belt off (the instrument panel lit up like Christmas lights). So this sounds exactly like what a power steering pump low on fluid would sound like.

The weird thing is, it sounds like the noise is coming from the front of the engine. I can't quite pinpoint it, not even with a stethoscope.

I had the dealer do a transmission filter and fluid change recently and they didnt' say anything about it. Should I be concerned? I was thinking since the sound was coming from the front of the engine area that it could be the chain and guides. THAT concerns me. If the transmission pump fails, I'll just have a fixed. This seems to be common with these cars.

Thoughts?

 

I just realized I accidentally put this in the 212 section... sorry. Mod, Please delete.