2004 Ford F-250 what I'm I missing

THREEQUARTERTON

MEMBER
2004 FORD F-250
6.8L
V10
4WD
AUTOMATIC
218,000 MILES

I have a 04 ford f-250 4x4, I replaced the pads, rotors and calipers on front and just pads on back, I bled the brakes after each job, and the brakes had pressure and worked excellent. A week later for no reason, it lost pressure. The pedal goes to the floor and the brakes barely work. I tried to re bled all calipers and still got the same results.I checked all vacuum lines and did'nt find any leaks. All brake lines are in good shape with no leaks.I have done numerous brake jobs and never dealt with an issue like this. Help will be greatly apprieciated

1 Reply

CARADIODOC

MECHANIC
33,871 POSTS

Most likely the master cylinder has been damaged. This is a common result of pedal-bleeding the system. On any vehicle more than about a year old, crud and corrosion build up in the lower halves of the two bores where the pistons don't normally ride. Pushing the pedal to the floor, either during bleeding or when surprised by a sudden leak while driving, runs the lip seals over that crud and rips them. Often that internal leakage shows up two or three days later.

Most shops include a rebuilt master cylinder in their repair estimate when a vehicle comes in with a popped rubber hose or a rusted-out steel line. It's safer to replace it than have to inform the owner later that more parts are needed or have them come back days later with a new problem.

You won't have this problem with a new master cylinder, but when it gets older, never push the brake pedal more than half way to the floor during the bleeding procedure.