I get brake pressure when the truck is off as soon as I turn it on it goes straight to the floor. I already changed the master cylinder.
have the same problem?
Tuesday, July 26th, 2016 AT 7:46 PM
Did this start before you replaced the master cylinder? How did you bleed the air out? What led up to this problem? Do you have anti-lock brakes? Are the rear brakes disc or drum? Have you checked the brakes?
Tuesday, July 26th, 2016 AT 10:56 PM
Yes I did it before I changed it, I bleed it with my friend I pumped the brakes he opened the valve, I do have anti lock, and I have drum brakes. I also put new brakes pads on the front and a new right front caliper.
Friday, July 29th, 2016 AT 10:31 AM
The first red flag is when bleeding with someone pumping the brake pedal, at any time did they run the pedal all the way to the floor? If they did, most likely the master cylinder was damaged. Crud and corrosion build up in the lower halves of the bores where the pistons don't normally travel. Running the pedal all the way down runs the rubber lip seals over that crud and can rip them. That results in a slowly-sinking pedal at first, then no pedal at all, and that often doesn't start until two or three days later.
The next thing is a scanner is often needed on some vehicles with anti-lock brakes to open some of the valves in the hydraulic controller. There is no other way to bleed the air out of some of the chambers.
Check the adjustment of the rear shoes, and look for a rear lining that is broken / rusted off the backing plate. That will cause a good pedal one minute and a low pedal the next minute.