Brake Problem- help!!
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Brake Problem- help!!
Hello everyone!
I have a 1996 F-150 4x4 with RABS. When at a stop, the brake pedal will go down almost to the floor. First, I bled the brakes and adjusted the rear. Then I replaced the Master Cylinder. That did not work, so I replaced it a second time. This still didn't work, even with bench bleeding the heck out of it to make sure no air was trapped. I then replaced the Power Booster, even though this isn't acting like a leaking booster that I have seen. I also replaced the small proportioning valve that is on the master cylinder. Yesterday I replaced both front calipers, because a mechanic I worked with did this to an older F-250 and solved the same problem.
There is not a leak anywhere and there isn't any air in the system.
The braking is good, but just at a stand still the pedal will drop to the floor (very annoyingly). Does anybody have an idea? Thanks.
I have a 1996 F-150 4x4 with RABS. When at a stop, the brake pedal will go down almost to the floor. First, I bled the brakes and adjusted the rear. Then I replaced the Master Cylinder. That did not work, so I replaced it a second time. This still didn't work, even with bench bleeding the heck out of it to make sure no air was trapped. I then replaced the Power Booster, even though this isn't acting like a leaking booster that I have seen. I also replaced the small proportioning valve that is on the master cylinder. Yesterday I replaced both front calipers, because a mechanic I worked with did this to an older F-250 and solved the same problem.
There is not a leak anywhere and there isn't any air in the system.
The braking is good, but just at a stand still the pedal will drop to the floor (very annoyingly). Does anybody have an idea? Thanks.
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From: Southern MD
Brake Problem- help!!
The Haynes manual states for 4-wheel ABS bleeding, a special piece of equipment must be used. It also plugs into the control module, because air gets trapped in the hydraulic control unit, (HCU). This is the only way to get the air out.
I don't know if this applies to the rear ABS only system too. You may have to check a better manual, or with a knowledgable brake tech to get your answer.
I don't know if this applies to the rear ABS only system too. You may have to check a better manual, or with a knowledgable brake tech to get your answer.
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Brake Problem- help!!
The ABS light was on when I was bleeding it this last time, but went off after bleeding the system and restarting the truck. I will look for the rear wheel abs bleeder and try that, Thanks!
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Brake Problem- help!!
What does a leaking vacuum booster do? I am just wondering because my brakes are getting a hair spongy and my booster is rusty blow the MC.
Matt
I think it might be my master cylinder replaced soon anyway.
Matt
I think it might be my master cylinder replaced soon anyway.
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Joined: Nov 2002
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From: Memphis, TN
Brake Problem- help!!
mrak
The booster is rusty because brake fluid strips paint and attracts water. Your MC is leaking. A leaking booster exhibits a stiff pedal (from the lack of assist) and a high idle (from the vacuum leak).
The booster is rusty because brake fluid strips paint and attracts water. Your MC is leaking. A leaking booster exhibits a stiff pedal (from the lack of assist) and a high idle (from the vacuum leak).
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Brake Problem- help!!
hmmm.... I bet the Master cylinder is leaking. I notice at stops that the pedal slowly sinks a few inches (but not to the floor) over a minute or so. It probably needs replacing. I'll try bleeding the lines, but my guess is it will need replacing.
Is this a tough job to do on your own? I had a brake tech do it last time, but it doens't seem that complicated.
Matt
Is this a tough job to do on your own? I had a brake tech do it last time, but it doens't seem that complicated.
Matt
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Brake Problem- help!!
Hey Mattman,
I had the same problem on my truck(1990,F150,302).
I changed my rotors, calipers, pads, drums, shoes, wheel cylinders, all hardware, master cylinder, bled the whole system plenty of times but kept getting that sinking feeling on the pedal when I would come to a stop.
My mechanic(who is a good friend of mine) then bled the ABS module like EPNCSU2006 posted and still didn't work.
He then( I don't know how he did it) bypassed the ABS module and the pedal felt real firm like it should. That's when we knew the ABS module had to be replaced. I got mine at NAPA, I forgot exactly how much I paid for it(maybe $150). Once we replaced it the brakes worked perfectly. All I can tell you is that I barely put my foot on the pedal and my truck stops like a charm!
Good luck, I hope this helps!
I had the same problem on my truck(1990,F150,302).
I changed my rotors, calipers, pads, drums, shoes, wheel cylinders, all hardware, master cylinder, bled the whole system plenty of times but kept getting that sinking feeling on the pedal when I would come to a stop.
My mechanic(who is a good friend of mine) then bled the ABS module like EPNCSU2006 posted and still didn't work.
He then( I don't know how he did it) bypassed the ABS module and the pedal felt real firm like it should. That's when we knew the ABS module had to be replaced. I got mine at NAPA, I forgot exactly how much I paid for it(maybe $150). Once we replaced it the brakes worked perfectly. All I can tell you is that I barely put my foot on the pedal and my truck stops like a charm!
Good luck, I hope this helps!
Posting Guru
Joined: Oct 2000
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From: Southern MD
Brake Problem- help!!
Originally posted by mrak
hmmm.... I bet the Master cylinder is leaking. I notice at stops that the pedal slowly sinks a few inches (but not to the floor) over a minute or so. It probably needs replacing. I'll try bleeding the lines, but my guess is it will need replacing.
Is this a tough job to do on your own? I had a brake tech do it last time, but it doens't seem that complicated.
Matt
hmmm.... I bet the Master cylinder is leaking. I notice at stops that the pedal slowly sinks a few inches (but not to the floor) over a minute or so. It probably needs replacing. I'll try bleeding the lines, but my guess is it will need replacing.
Is this a tough job to do on your own? I had a brake tech do it last time, but it doens't seem that complicated.
Matt
Replacement isn't hard, just don't bugger up the flare nuts removing them. Get the proper wrenches and you should have little problem.
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From: Linwood, N.J. USA!
Brake Problem- help!!
Originally posted by IES
Hey Mattman,
I had the same problem on my truck(1990,F150,302).
I changed my rotors, calipers, pads, drums, shoes, wheel cylinders, all hardware, master cylinder, bled the whole system plenty of times but kept getting that sinking feeling on the pedal when I would come to a stop.
My mechanic(who is a good friend of mine) then bled the ABS module like EPNCSU2006 posted and still didn't work.
He then( I don't know how he did it) bypassed the ABS module and the pedal felt real firm like it should. That's when we knew the ABS module had to be replaced. I got mine at NAPA, I forgot exactly how much I paid for it(maybe $150). Once we replaced it the brakes worked perfectly. All I can tell you is that I barely put my foot on the pedal and my truck stops like a charm!
Good luck, I hope this helps!
Hey Mattman,
I had the same problem on my truck(1990,F150,302).
I changed my rotors, calipers, pads, drums, shoes, wheel cylinders, all hardware, master cylinder, bled the whole system plenty of times but kept getting that sinking feeling on the pedal when I would come to a stop.
My mechanic(who is a good friend of mine) then bled the ABS module like EPNCSU2006 posted and still didn't work.
He then( I don't know how he did it) bypassed the ABS module and the pedal felt real firm like it should. That's when we knew the ABS module had to be replaced. I got mine at NAPA, I forgot exactly how much I paid for it(maybe $150). Once we replaced it the brakes worked perfectly. All I can tell you is that I barely put my foot on the pedal and my truck stops like a charm!
Good luck, I hope this helps!