Last night my mechanic picked up my '04 1.9TDI B6 A4. Ive been having problems with the heating system. IE: only getting warm air when car is moving/engine is in motion, then cold air when car is idle. Temperate guage never moves past 90 by the way. So anyways, lastnight he's diagnosed the water pump was broken and not circulating water/coolant at all. On his way back to my house to drop off the car, he calls me to state he was driving along, heard a loud ping, and lost all power of engine. Pulls over, seems to be excess oil on the road and on the side of engine block. Engine wont start. Hes figured its possibly blew a piston down through the bottom end, through the sump, or out the side of this block. Thus possibly meaning a new engine?! Could anyone shed any light on this. Im no expert, but Im pretty sure a car shouldnt be driven with a broken water pump? What damage could this have caused?