Brakes lock up after about five to ten minutes of driving

Tiny
JKIESEL
  • MEMBER
  • 2004 FORD MUSTANG
  • 4.6L
  • V8
  • 2WD
  • MANUAL
  • 135,000 MILES
All 4 wheels lock up and I have to floor the gas to go 45 in 2nd gear. When this happens the brake pedal is stiff and doesn’t want to depress. I replaced the hydroboost and it fixed the problem for 3 days, then it locked up again.
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Wednesday, April 14th, 2021 AT 10:50 AM

7 Replies

Tiny
KASEKENNY1
  • EXPERT
Sounds like you have a master cylinder issue but the hard pedal does point to a booster issue.

However, how do you know it is all four wheels that are locking up? Also, what do you have to do to get it to release?

https://www.2carpros.com/articles/how-to-replace-a-brake-master-cylinder

What I would do is get them to lock up again and then lift the vehicle off the ground to find which wheels are actually locked up.

https://www.2carpros.com/articles/jack-up-and-lift-your-car-safely

Clearly we need to be sure it is all wheels because that will change what this could be. I understand it may feel like all of them but it may not be all of them unless you have proven that a different way.

Let's start with this and go from there. Thanks
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Wednesday, April 14th, 2021 AT 4:48 PM
Tiny
JKIESEL
  • MEMBER
I know all four lock up because after it gets really bad all four are smoking. And they all have intense wearing on the rotors.
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Thursday, April 15th, 2021 AT 6:35 AM
Tiny
JKIESEL
  • MEMBER
And I have to let it sit for a few hours to get the brakes to release. But it only lasts for about 10 minutes.
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Thursday, April 15th, 2021 AT 7:59 AM
Tiny
KASEKENNY1
  • EXPERT
In the 3 days that it was "fixed" did you drive like normal and it operated the entire time with no issues?

If so, then was this the same issue that you replaced the booster for?

Did you just replace the booster or did you get an assembly with a new master cylinder as well?

See below for more detail.

What I suspect is happening depending on these questions, is the brake push rod is sticking and causing the brakes to drag.
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Thursday, April 15th, 2021 AT 7:15 PM
Tiny
JKIESEL
  • MEMBER
Yes, this is why I replaced it in the first place. But I only replaced the booster. Would the brake push rod just need to be lubed?
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Friday, April 16th, 2021 AT 7:41 AM
Tiny
KASEKENNY1
  • EXPERT
You could try that but I suspect the rod in the master is where it is sticking so that means replacing the whole unit would need to be the solution.

I am not sure this will work but try getting it to lock up again and then push down and actually pull up on the brake pedal to see if they release quicker then before. I doubt it will be an instant thing but it may.
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Saturday, April 17th, 2021 AT 8:19 AM
Tiny
JKIESEL
  • MEMBER
Thank you, I will try that.
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Wednesday, April 21st, 2021 AT 12:04 PM

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