I have an ML320 with 250K miles. Just started to have a whinning noise, noticable increase when i speed up and then whinning goes down as i slow and come to a stop.

Place in neutral when driving and rev engine slightly, does not change whinning pitch. Hard to say where it is coming from. seems like rear at times then other times i think it from the engine compartment.

am wondering if there is a rear differential issue.

Other than that it runs very well, noise is annoying and I will get it looked at and diagnosed by MBUSA dealer.

Oh by the way, turn music up load i dont hear a thing drowns it out, ok so much for the humor with respect to music.

Has anyone experienced this ?

 

you may have an issue with your driveshaft support bearing.

 

Yeah, I had the same thing, then I dropped my wife off at the mall. Whining went away!
JK/ I had the center support bearing go out a few months ago on our trip to FL. Mine sounded more like a clicking sound than a whining sound at slow speeds. But, definately had that "its coming from the front, no it's coming from the rear" thing.

 

whinning noise could be a couple problems power steering, transmission, or even transfer case .

 

Power Steering pump?

 

Just found out that its the power steering pump probably, seems as the cars gets to temperature turning end to end gets harder and whining in front whining gets louder, strange theres no leaks or anything, doesn't seem it's the Trans or transfer case it's in excellent condition. But seem like I had the sams issue lol.