Changed the oil and filter yesterday and decided to clean the EGR valve at the same time. 65k on the clock and I had noticed it made smoke whenever you accelerated hard. When I got it off was ama zed at the state of it. The pipe must be at least 50mm diameter and was all but blocked, you could just get your finger in the middle - all the rest black tarry coke.
Cleaned it all out and reassembled; no more smoke!
Hi as you have now cleaned the EGR valve you could now blank the valve off by making up a small blanking plate from a piece of 1mm steel or alloy plate, this would then stop the future build up of the black sludge in the valve and inlet manifold and the engine would then not have to ingest its own exhaust so it will run better and you may get a few more MPGS.
I have owned 3 tdci diesels and have done this mod on all of them and i found it well worth doing just to keep the inlet manifold and EGR valve clean.
Its a easy mod to do as long as you know your way around the engine and the only cost would be a few pence for the metal for the blanking plate i made mine from the base of a old aluminium saucepan! and you should be able to complete the job in an afternoon.