Originally Posted by MrPig
It's the metal portion of the outlet line. The cooler itself is dry as a bone on the exterior.
you could try and patch it but if it failed because you moved it while poking around I would replace the whole thing.
I don't know how much BMW wants for one of those lines but I expect you could replace it with an AN setup for the same price and source all the pieces needed locally. Plus AN stuff is cool as hell.