I have a 1987 560 SL which I just replaced the master cyclinder, completely changing the fluid and bleeding the brakes. The brake pressure was fine until I started the car and then the peddle went straight to the floor. Since the car is 150 miles from the nearest dealer, towing is not an option. The dealer says its the master cyclinder and the people I bought the master cyclinder say there must be a air leak with the power booster. Does anyone have any suggestions?