Took the opportunity whilst replacing the water pump on the '98 D1 to also replace the timing belt. When I bought the vehicle, 25,000 K's ago I had asked it's previous owner the questions you need to ask, one being, has the T-belt been replaced and according to the log it had been replaced at 170,000, but because he had "fudged" some other history stuff and told some "porkies" about the sight unseen condition of the D1, (I bought it on e-bay...... I know, I know, ya pays ya money and takes ya chances!), well because I didn't believe what he in all probability had put in the book I have never really trusted the vehicle for a long trip, but after initial various "fixes", it really has turned out to be a good unit, now even better.
Upon opening up the Timing belt case I found that the belt was in a good condition commensurate with only having done low Klm, but what I also found was that with the crank on TDC the camshaft was a full tooth retarded and the fuel injection pump half a tooth advanced on the pin position.
This Tdi has never gone as good as our old '97, (we have two, an addiction of some sort), until now, it always ran hotter under all circumstances, I have capillary type mech temp gauges fitted to both that register small changes in engine temp, so it is noticeable, it also lacked oomph on the hills, with little or no response at highway speed.
Since it has a full 100,000 less klms on the clock than the '97, all the cooling system etc is in "nicer" condition, and now with the new belt and re set right on the marks it is running so much better and at least 5-8 deg C cooler in our tropical heat under our normal highway conditions.
I had heard that these engines can suffer a little "miss-timing", and they will start and run reliably but the difference here is pretty remarkable.
I think whoever replaced the last belt just did a "quickie" and did not really reference the marks properly, it was good enough to get it to run again and that was it. I am very happy with the result now things have been put right.
I hope this might help someone who has a hot or lacking power Tdi Gaz.