Valves breaking in 2001 vw jetta tdi?

Just a guess, as I don't own one of these; VW engines are minimal or zero-clearance, meaning that the valves will hit the top of the piston if they aren't working correctly. If the timing belt (which it tied in with the valve operation) breaks, some valves may be stuck in the open position, and they could be clobbered by the piston. If the timing belt was recently replaced, they might not have correctly timed the valves.