Probably the slave cylinder. That's usually how they behave when they are no good.
SOURCE: 1992 Ford F350 Dually Diesel Truck Brake System problem.
Adjust your rear brake shoes. Then rebleed the system. Start at the master cylinder Bleed master first then the wheel furthest away from the master (right rear then left rear then right front then left front. Do that and your pedal should be good.
SOURCE: brake pedal keeps creeping down, but there are no leaks.
check your brake booster and also make sure the rear shoes are adjusted up where they belong. If they are not adjusted up the brake pedal will go farther and farther toward the floor and get spongier as they go farther out of adjustment. If you adjust them up and they back down again change your self-adjusters and springs. They are readily available at your local parts store.
They need to be bleed again all four wheels but your vacuum pump may be bad since diesels don't have vacuum then have to have a pump, check that the booster one way check valve is good if you can blow thew it both ways it's bad, to bleed start from the wheel farthest away from the master cylinder pump the brakes 5 times and hold down then open the bleed valve keep doing this until you get clear fluid out of each wheel once you have done that if it is still mushy and you know you have vacuum re bleed with engine running this will help push more out with power assist. most like the hard brake pedal had to do with no vacuum check out the pump. You may also have to reset the 2 way check valve if you need help with this let me know.
74 views
Usually answered in minutes!
×