i have a '92 f150 supercab xlt 4x4. 302 v8 5.0L 200,100 miles. i was driving down the road when someone pulled out in front of me, i locked up the brakes at about 55mph and completely blew out my brake system. Brake fluid was leaking from front and rear lines. i've replaced both rear wheel cylinders, the master cylinder, and all of the brake lines. we have been power bleeding and bench bled the master cylinder, even tried gravity bleeding, there is absolutely no air in the lines and the abs box which is located on the front driverside underneath on the frame. now if you pump the brakes you get a pedal, if you let off and then press down again the pedal goes to the floor. my friends and i are out of ideas, so i figured someone on here might be able to help.

Gotta ask - Are the back brakes adjusted properly? Test pedal with parking brake applied if working or fix that too and pedal should stay firm - test just sitting still. If it can't stay with a firm pedal then, then it might need another try at the master cylinder especially if rebuilt,

T
_________________________________________


Tom Greenleaf - MetroWest, Boston
http://acsource.net/acforum/index.php