If you don't know when the timing belt has last been changed, then of course you should change it on ANY of the VW diesels.
Just to add my own data point to the mix, my '02 jetta wagon just passed 240,000 miles and runs flawlessly.
If you don't know when the timing belt has been changed on any timing belt engine, you should change it if there is any visible wear and it is possibly past the original service interval.
I say that because they claim that the belts on the FSI gasser engines are good for 100,000 miles. But i changed mine at 80k because i got nervous.
If you don't know when the timing belt has been changed on any timing belt engine, you should change it if there is any visible wear and it is possibly past the original service interval.
That is a poor policy. If you are not CERTAIN when it was last changed, just do it now. If it has any visible wear you may only have minutes. I have seen a fair number of broken timing belts and only a couple had anything like apparent "wear".
I've done compression tests on 3 1Zs all with around 500 000 kms and they have all been in spec. I've pulled the heads on at least 6 and visually I saw nothing to warrant a rebuild.
I have 2 B4s with 462,000 and 491,000 miles still running good
I took a 1,000 mile trip a few weeks ago in my '02 and it did not use a drop of oil.