Strange deep UUUUU noise at 1500 rpm and above until gear shifts

[Marcuss]

Hi All,
I have clk 320 2003 petrol 100k miles,

When I drive slowly I notice a deep UUUUU sound between the 3rd and 4th gear at 1500 rpm and above until it shifts. It seems like the car wants me to accelerate for a quicker gear shift.
It is long and deep (UUUUUUU) something similar if you would drive on frequent small waves solid road (no shaking only sound).
Recently done gearbox service but the issue remains.

Any idea what it can be or anyone had a similar issue?

 

[AMGeed]

Hi All,
I have clk 320 2003 petrol 100k miles,

When I drive slowly I notice a deep UUUUU sound between the 3rd and 4th gear at 1500 rpm and above until it shifts. It seems like the car wants me to accelerate for a quicker gear shift.
It is long and deep (UUUUUUU) something similar if you would drive on frequent small waves solid road (no shaking only sound).
Recently done gearbox service but the issue remains.

Any idea what it can be or anyone had a similar issue?

Was the issue present before the gearbox service or did it begin afterwards?
Was the ATF level checked correctly after the service?
Was the service carried out by you, a regular garage or a Mercedes independent specialist?

At a slow speed in 3rd and 4th gear at 1500rpm, you are close to stalling. Are you sure that's not what you are experiencing?