Break preasure

FADGE

MEMBER
2001 FORD F-250
200 MILES

Ok where to start, I recently changed the rear discs and one of the calipers as it was ******ed.

Everythign was fine until today. I went to break and pedal went right to the floor. Breaks still worked once the pedal hit the floor sorta.

The next push was normal and then the next push after that the pedal went back to the floor again with no preasure.

I had my mechanic come by as hes the one that does all my work. He bled the breaks over and over and over again and still nothing changed. He mentioned that there was a ton of preasure in the front breaks but very little in the back.

The only thing he could think of was something caught in the line and they may need to be blown or the master cylinder was shot, or possible something to do with the ABS thingy (yes thingy is a technical term!)Under the hood.

So I have a truck stuck in a parking lot and its the only way I make my money. So what do I do, take the chance and go buy a master cylinder in hopes that will fix the problem or?

Ill also mention that as skilled as he may be, my mechanic is a back yard mechanic and doesnt have all the fancy equipment.

PLEASE HELP!

6 Replies

RIVERMIKERAT

MECHANIC
6,110 POSTS

Possibly a proportioning or diverter valve. Loosen the lines to the rear valve on the differential and have a helper press the brake pedal. You should see fluid come out. Tighten the fitting BEFORE the helper lets off the pedal. If no fluid, trace the hard line forward to the diverter valve (on the frame under the master cylinder usually) Loosen the INLET line and have your helper press and hold the brake pedal. No fluid? Bad master. Fluid? Plugged line between diverter and proportioning valve.
Fluid from rear axle-mounted valve? Repeat the process on both rear wheels (loosen line and press pedal).

If you don't get any fluid from the valve on the frame, perform the same test on the ABS hydraulic control unit: remove the fluid inlet and depress the pedal. The presence of fluid points to a faulty hydraulic control unit.

All that being said, one thing sticks out to me: you said the pedal goes all the way to the floor, or went all the way to the floor once or twice. THIS tells me the master cylinder is probably bad.

You should be able to check the electronic portion of the ABS system using a scan tool.