TD5 Oil Rotor Filter

That's what they do, they're supposed to sound like that, as they spin at about 20,000RPM

It's when you don't hear them, you know they're blocked or broken.

Mine's silent but has only done 48k miles. What oil have you got in there?

Switch the engine off at idle. Hold a long screwdriver against the rotor casing and put the other end to you temple and you should hear it spinning. Sometimes you dont need any help to hear it. Its normal.
Are you sure its not the turbo winding down because if it is its running on dry bearings when you switch off. You should let the engine idle for a few minutes before switching off with any turbo engine.

Thanks for your reply im gonna change the oil tomorrow and see if that helps. cheers