I'm in the throws of a ZD30 to TD42Ti conversion. The TD42Ti donor engine was alleged to be a one owner, 155 000km, tested and reported to be running like a dream. Conversion complete, first start and there's a knock in the bottom end?? What could go wrong during the conversion to cause this? Is there any way an engine could be bodgied up to run well during testing and crap itself shortly after? Or is someone telling porkies? Thanks for reading.