F-150 Brake problem

ford
brakes
f150

#1

Hi everybody. My sister in law has an '01 F-150 4x4 with disc brakes all around that had a fading brake pedal. The brakes seem to be working ok but the pedal slowly goes to the floor with the motor running or not. I naturally replaced the master cylinder, but it did the same thing. Thinking I got a bad unit I took it back and got another one and installed it. You guessed it, same thing. I cant find any leaks anywhere, no indicator lights, no vibration. Im confused. Ive done many brake jobs and this is the first time Ive run into this. Any thoghts? Thanks.


#2

Does this truck have ABS? If so you might have a problem with the hydraulic module. Verifying that the leak is in the unit will be difficult. Throwing a part at it will be expensive.

Let us know how this comes out.


#3

Remove the brake lines from the master cylinder and plug the outlets. Pump the pedal several times and then hold constant pressure on it for a minute. I once found 12 new voltage regulators to be defective.


#4

yeah its got ABS. No ABS light on the dash. I will try the plugging the lines if I can find something to plug them effectively. I hate to give it back to her without it being fixed. Thanks for the ideas.