'86 Bronco brake pedal goes to floor brakes lock up

Tiny
SILVERCIN29
  • MEMBER
  • 1986 FORD BRONCO
177,000 miles, 6 cyl, full size bronco. I just bought this a month ago and drove it minimally. Brakes just started going to the floor and not stopping me. If I pump them they will build pressure back up and start slowing me down. Then they will loose pressure and go back to the floor again. One time while doing this the brakes and/or tires locked up. According to my fiance (who's been the one driving it) there doesnt appear to be any fluid leaking from the lines or wheel wells. And he said the pads or whatever is in there look o.K. He is not by any means a mechanic however he is good at repairing things if people tell him what to do. I havent replaced anything yet. I was going to start with the master cylinder, But the guy at Auto Zone said that with the brakes locking up as they did that one time he was concerned that it was something else and said to look for leaks. I dont have the money to trial and error the problem or I would just take it to a mechanic. I had a chevy once upon a time that did something like that and was told it was a brake/vacuum booster. Some guy also said that it could be the boot? I will donate a dollar, I WILL donate MORE when I know that someone out there will try to help me. Thank You Cindy
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Wednesday, March 21st, 2007 AT 11:50 AM

7 Replies

Tiny
TAURUSWHEEL
  • MEMBER
I would hazard a guess and say that it may be the master cylinder is failing, the seals may be shot. The booster doesn't stop you, it provides assist to make it easier to stop. Do you remember the days of manual braking systems? If the master cylinder seals are bad, it could cause the brakes to lock up, remember you're pushing the pedal all the way to the floor, that would be way more then maximum braking if all worked, could be like an abs system with a faulty wheel sensor, that wheel can do strange things. I would carefully check all wheels seperately for any leakage, however with the brake system, even if one line, wheel cylinder whatever leaked, there should still be some stopping ability, the system is designed that way to have at least one diagonal set of brakes able to slow the car down.
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Wednesday, March 21st, 2007 AT 3:13 PM
Tiny
PEPPERMRJ
  • MEMBER
Bleed the brakes first. If the pedal is good you can rule out the master and start looking for leaks. Rusty brake lines and rear wheel brake cylinders are the first thing that come to mind. Did your significant other pull off the rear drums and peel back the rubber boots on the wheel cylinder. Bet fliuid pores out.

Good hunting and let usk know. :)
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Wednesday, March 21st, 2007 AT 9:00 PM
Tiny
M_H_RITZEL
  • EXPERT
Check the brakes, have seen where a broken shoe would lock up a wheel.
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Wednesday, March 21st, 2007 AT 9:37 PM
Tiny
SILVERCIN29
  • MEMBER
Ok thanks guys I will have him check into it. How long will this topic stay open? Its supposed to pour for a few days here. Ill let you know what he finds.
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Thursday, March 22nd, 2007 AT 10:25 AM
Tiny
MERLIN2021
  • EXPERT
Also have him take a small sample of the fluid in the master and add some water. If you see any oil beads, some poured oil or trans fluid in it. If that is the case all rubber parts must be replaced and the lines flushed with alcohol! Make shure he doesn't add water to the master! Do the test in a paper cup.
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Thursday, March 22nd, 2007 AT 2:38 PM
Tiny
M_H_RITZEL
  • EXPERT
We will be here, just let us know what you find.
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Thursday, March 22nd, 2007 AT 6:02 PM
Tiny
MARCKIMMEL
  • MEMBER
If you havent already fixed it.I had the exact same thing happen to my 86 fullsize bronco. The problem, it was the brake booster. But I could be wrong about yours. So try your master first. If it dont work. Try my idea, it worked for me.
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Thursday, April 12th, 2007 AT 3:14 PM

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