What's causing our 20-year-old Audi 80 to lose power?

We are the proud owners of a 20-year-old Audi 80 TDI (bought from new), now with 174,000 on the clock. Over the past year it's lost much of it's pulling power. It struggles with even the slightest inclines and takes a good while to get rolling from stationary. Has it had its day, we wonder? The problem is that we love the car and question whether we shall see the like of it again. So, in desperation, we come to you. Have you encountered such a problem with other "vintage" turbos and more importantly, know of anything that could be done to improve matters. Our garage has tried a diesel additive on two occasions without much success.

Asked on 23 February 2013 by WB, Norfolk

Answered by Honest John
Two things happen with these from around 150,000 miles (I know, my brother had one which clocked up the miles much more quickly than yours has done). One is that the injectors start to wear from around 80,000 miles and dribble neat diesel down the bores. Eventually wear takes place down the path of the dribble, the rings can't meet the sides of the bores and the engine starts to drink lube oil. The other is that the EGR gets blocked, and I think that's what's happened to yours. Sometimes they can be cleaned out (a very nasty job) but usually they have to be replaced.
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