Brake pressure

Tiny
MICHAEL MCCALL
  • MEMBER
  • 2000 FORD F-150
  • 5.4L
  • V8
  • 4WD
  • AUTOMATIC
  • 167,000 MILES
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.
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Tuesday, July 26th, 2016 AT 7:46 PM

11 Replies

Tiny
CARADIODOC
  • EXPERT
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?
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Tuesday, July 26th, 2016 AT 10:56 PM
Tiny
MICHAEL MCCALL
  • MEMBER
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.
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Friday, July 29th, 2016 AT 10:31 AM
Tiny
CARADIODOC
  • EXPERT
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.
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Saturday, July 30th, 2016 AT 12:17 AM
Tiny
CHRISTOPHER NULL
  • MEMBER
I see that you mentioned a scanner. What type of scanner? And how would you check it on the scanner?
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Monday, May 28th, 2018 AT 5:45 AM
Tiny
KEN
  • ADMIN
You need a scanner that can work the ABS valves open when the system is being bled. Can I ask if you had any kind of work done or did this just happen?
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Monday, May 28th, 2018 AT 10:29 AM
Tiny
CHRISTOPHER NULL
  • MEMBER
I blew a brake line on a test drive. I replaced the bad line and that is where I am at now.
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Tuesday, May 29th, 2018 AT 3:20 PM
Tiny
CHRISTOPHER NULL
  • MEMBER
I also heard of the auto bleed sequence from the scan tool also.
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Tuesday, May 29th, 2018 AT 3:23 PM
Tiny
ASEMASTER6371
  • EXPERT
If you have a scan tool, go to the ABS portion of the menu and then look for bleeding procedure. This procedure will not run if you have any active codes. Make sure the ABS light is not on. If it is, clear the code and then perform the procedure. You may have to do it several times to get all the air out of the unit.

Roy
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Tuesday, May 29th, 2018 AT 3:54 PM
Tiny
CHRISTOPHER NULL
  • MEMBER
My best friend just dropped his off tonight. So tomorrow, as soon as I get home, I will be trying it out. I have heard if you can get the wheels to slide it will do the same thing. Is that hard on the unit? Neither my brake light or ABS light is on in the cluster.
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Tuesday, May 29th, 2018 AT 5:39 PM
Tiny
CHRISTOPHER NULL
  • MEMBER
I have seen this issue on several different forum sites. Has anyone actually found a solution yet?
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Tuesday, May 29th, 2018 AT 5:41 PM
Tiny
ASEMASTER6371
  • EXPERT
No, getting the wheels to lock does nothing. It will not bleed the system.

That is false information.

Roy
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Tuesday, May 29th, 2018 AT 5:49 PM

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