I really need help with brake prob
Thread Starter
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New User
Joined: Sep 2008
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I really need help with brake prob
ok guys I have replaced master cylinder, r-abs valve, and have properly bled the brakes however brakes are still malfunctioning brakes pump up hard with the truck off but with truck running brake pedal goes to the floor please anyone? 1991 f250 idi
Cargo Master
Joined: Jan 2004
Posts: 3,118
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From: South Dakota
If you pump the brake pedal with the engine running will the brake pedal come up? Did you do any other brake work at the same time? Why did you decide to replace the master cylinder and r-abs valve in the first place.
Post Fiend
Joined: Jan 2005
Posts: 8,402
Likes: 10
First check that the rear brake shoes are properly adjusted. Then bleed the brakes in this sequence, right rear, left rear, RABS module, right front, left front, closing bleed screw each time before pedal is released.
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New User
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I bled the brakes in the proper order including the abs valve with the motor off. The back brakes are ajusted up and they are firm and hold while the engine was off. When the engine is started the pedal goes soft and bleads down to the floor. It will pump up but upon holding the pedal it bleads back down to the floor swiftly. This truck sat for 2-3 years. The r-abs was leaking as was the master cyl. that is why it was replaced. I also replaced the back break line from the R-abs to the driver side rear brake.
Also within the last 8 months the vacuem pump and the booster has been replaced. This truck is a brake nightmare!
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New User
Joined: Sep 2008
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Did this already, Also replaced the master cylinder again thinking that the replacement was bad, no such luck!. A friend is an ASE mechanic for Ford. He told me the sequence for bleading this model from the shop manual but he is stumped as to what is causing my problem!
