Getting a warranty on the drive train is one thing, getting a warranty on the turbo and emissions kit is another. At this age and mileage the engine will probably still be fine, its the bits that are bolted to it that will more than likely give issues and they will not be covered.

You have already spotted that there is a potential issue so I would suggest you just walk away. These cars are plentiful and you will soon find another hopefully with no smoke.

But if it was me I would look for a 2 litre (or even 1.8) petrol. Much less likely to be a money pit.

After doing some reading I see it's important to note if the smoke is white or blue. I may have to go back and look again because I think it was more blueish.

For 2000.- it seems like a good deal if the smoke isn't a problem.

I personally think 3 thou is a bit steep for the car you describe, at that money it really should have less than 100k, a FSH and certainly no smoke or slight roughness. Have you considered a mk.2 Focus 1.8 tdci?. This model has the bulletproof SOHC 8v engine, (maybe old fashioned), but reliable as hell, no DPF to go wrong and simplicity itself to service and maintain. I've had two of these cars (still run one now) and have covered well over 100k in seven years with no major issues whatsoever. Plus, the icing on the cake is, for your budget of £3k, if you scan the internet, you should be able to pick one of these up on a 58/09/59 plate with sensible mileage for well within your budget. Hopefully food for thought for you. Good luck.