My 1986 325 bmw has brake problems. the brake pedal goes all the way down to the ground and some times makes a spring sound? and the back brakes r not working there seems to b no fuld going to them and the brake pedlals r getting rust do to no presser? also on the driver side in front of the back tire an object that is linking air and it is apart of my brake line but idk what it is or how to fix it? and thank you to who ever reads this to help me out with my car.