1.8 TDCI whine when revving or releasing accelerator

[FF18]

Hi,

My 2007 Focus 1.8 TDCI has developed this sound when pressing / releasing accelerator:

 

I've checked the boost pipes and I can't see anything. The noise seems to go away after a few miles of driving but it reappears if the engine is turned off and back on later (with the engine still warm).

Any ideas?

[ajzetecs]

its your alternator mate, my focus done exactly the same noise, go get tested asap because you will loose a lot of functions like power steering which happened to me and was very unsafe

[Povo]

The problem was found. Exhaust manifold gasket has been blown from heat. I will be replacing both the intake and exhaust manifold gaskets.

The noise was coming from the back of the engine near the EGR valve.

Cheers for your help! :)