Strange sound from engine...

that is the cold start pump or sai pump the rivets would have come out of it and the air is escaping you can delete the pump completely from the system.
if you look down the front of the engine you will see a large black cylinderish shaped box thing with two pipes and an electrical connection going to it if i remember right, its been a very long time since ive seen in the engine bay of a 1.8t but im certain that is what is making the sound.