My son's 94 Nissan Sentra won't go into 2nd gear. He drove into some water, had a hydraulic lock and broke the 1st piston oil skirt and bent the connecting rod. I replaced them, plus rings and bearings on all four pistons, had the head checked, etc. The car starts fine. There's a metal line off the top of the transaxle that has a hose attached which isn't connected. Is this a vent, or should it be connected to something? I don't know much about cars, but followed the instructions in the manual. Thanks in advance for your help.