hi new to the site looking for some advice from the experts, i'm just buying a 1997 325tds as a non runner its proving to be a real head scratcher

........ Car was driving fine went in to have a new clutch and when the previous owner went to collect it was "as noisy as a transit and smoking bad" the mechanic said not his prob only changed the clutch , after some advice they put in new flywheel still no change. More advice and the crank sensor was changed still the same car was then taken to so called specialist who replaced fuel filter and put on computer put said return no faults , car still the same and "smokes like a train". Now been sold to me as non runner. I no worse case i will have to change engine but before i do has anyone any advice or ever come across this
thanks