I was given a 97 Jetta TDI with an AHU engine that had the timing belt go at 40K miles and of course crashed all valves, lifters and cam. There was portions of belt appearing to be melted to the intermediate shaft pulley which made me suspect vacuum pump or oil pump. The oil pump seemed OK but vacuum pump seemed to have some binding plus the port on the top was broken. The pistons did not have any visible marks on them so I replaced the head and vacuum pump. I got it all back together and it ran great except for a noise that sounds like a bad hydraulic lifter (at least what I'm used to hearing in say a gas OHV V8 engine). I've removed the oil fill cap and listened but nothing from there so I removed the valve cover twice and checked for noise while running and could not determine that it was a lifter problem. The noise sounds louder the under the car. Presently I have the pan off and checked the rod bearings visually and they all appear to be OK just normal looking wear. While each rod was disconnected I could not detect any play when pushing and pulling on the rods that would indicate a problem with the wrist pin end. What are the typical things that go wrong after a head is crashed? Is rod bearing damage typical or visible? Does anyone have an idea what I should be checking?