Vibration and low humming sound

[Henksla]

My car vibrates randomly a which produces a low humming sound, this occurs at various speeds , revs and gear . The car is a 2008 C320 CDI Estate automatic , with 330,000 km on the clock.
The vibration and the sound do not seem to affect the peformance. Does any one have an idea

 

[Blobcat]

Hello and welcome,

What condition are the engine mounts in? At that "mileage" hey could be worn out.

 

[Henksla]

Hello, thank you for the very quick reaction, to be honest I do not know, I own the car from new and the car is wel maintained. But the engine mounts I had never looked at.

 

[Wighty]

Rear differential oil low ?

 

[alexanderfoti]

If you have never done the mounts, then do them, especially at that mileage.

Is it RPM dependent? If so could be TC or gearbox related, but definitely do the mounts first.

 

[malcolm E53 AMG]

At 200k+ miles it could be anything from a worn gearbox, wheel bearings to a differential problem the car really needs a thorough inspection from a good MB independent or you could end up just throwing money at it

 

[matthew k]

Rear differential oil low ?

Do these cars suffer with coolant to gearbox oil infiltration via the radiator?

 

[Wighty]

Do these cars suffer with coolant to gearbox oil infiltration via the radiator?

The op’s car at 2008 doesn’t

 

[matthew k]

The op’s car at 2008 doesn’t

Actually, I think I've suggested this on a number of occasions on post 2008 cars, that's annoying sorry, bit too enthusiastic!!!

 

[Henksla]

Rear differential oil low ?

Goodafternoon I have not had that checked yet

 

[Henksla]

At 200k+ miles it could be anything from a worn gearbox, wheel bearings to a differential problem the car really needs a thorough inspection from a good MB independent or you could end up just throwing money at it

Goodafternoon, wheelbearings I doubt that as I had them replaced two years ago, and yes throwing money at it is my experience :-(

 

[Henksla]

If you have never done the mounts, then do them, especially at that mileage.

Is it RPM dependent? If so could be TC or gearbox related, but definitely do the mounts first.

No that is the problem , I can not see any correlation between rpm's and the vibration, also I do not feel anything on the gearlever when the vibration humming starts , it just comes and goes seemingly randomly . But yes I will have the mounts changed.