Mercedes: Mercedes A 140 transmission noise, mercedes a140, rear gears

Question
I have just started driving my wifes Mercedes A140 and it has an annoying(to me)transmission noise/whine which I think coming from the rear. The car drives well and the noise stays constant when the clutch is put and gets faster as the car speeds up.  I dont think its wheel or brake related ie not something catching

Any Ideas?

Answer
Chris,
Do you mean that the noise is present when you depress the clutch and the vehicle is rolling?

I would place the vehicle on the rack and check the differential grease.
With the plug removed, you should be able to insert a finger and just touch the dope. Do not allow a service person to over fill the casing,as an axle seal at the wheel can begin to leak.

While on the rack you should place the vehicle in gear and rock the rear wheels back and forward to determine if you have a U joint that need repair, or excess play in the rear gears on in the transmission.

Good Luck
Rob