On an 02 grand am I am having a problem with the brakes going soft on me. The brakes get hard when the car is off but when you turn it in they go to the floor. It will stop the car at the floor. Any clue. I changed the abs new brake lines. Somewhere I must be geting air into the system. On the back brake are drums. The piston on the drum where it pushes the brake on the drum. When pressing the brake I had fluid come out of the the piston where the rubber seal is. Is that normal or is it bad? ty