Hi all, Newbie here, just after some advice please?

I have a 55 plate e320 cdi avantgarde estate 3.2L

I have recently developed a problem. There is a horrible shrieking noise when accelerating. It cuts in at about 2k revs and stays on all the way up to max revs. It also screams when I lift off and stops back at 2K revs again.

I have had the turbo taken out and checked by Essex turbos who have said there is nothing rong with it and it is all aligned properly and all the veins and valves are in order and working properly. The local MB dealer said it was the turbo. I took it back to them today and they said it was the pulleys and belts. I took it to my local garage who whipped the belt off and it still made the same noise.

A few times the noise has stopped but on the whole it is there and is driving me mad!!

Has anyone else had this problem and if so what was the cause of the noise if it is not the turbo or belts and pulleys?

Any help would be much appreciated as it is embarrasing driving around in a decent car with everyone looking round thinking 'what the hell is that?'

The noise is very loud and is easily heard in the cabin

Thanks Compo