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Intermittent brake locking issue diagnosis


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YourMinky
User

Dec 4, 2017, 8:41 PM

Post #1 of 21 (572 views)
  post locked   Intermittent brake locking issue diagnosis  

2000 Hyundai Elantra. The brakes are locking up intermittently in stop and go traffic for the last few months. I removed the front tires. The brake pads were locked solid and the rotor wont rotate at all. Brake and wheel were blistering hot. Front driver side wheel/brake was hotter than front passenger side. Note that brake master cylinder and reservoir are closest to the front driver side. Back brakes were not hot. When the wheel/brake lock up, the brake pedal is stuck at the up position. Pressing with all my might wont make the brake pedal go down. The car drags and struggles to move forward or backward when it happens.
15 minutes after turning the engine off, the brake pedal would go down a little bit. After 30 minutes everything becomes normal, the brake pedal goes down and up normally, the car drives normally afterwards for the rest of the day.
The car also runs louder than before. Rotating the steering wheel to the right diminishes the road noise partially.
People gave me a whole list of things that could be causing this. After this locking issue started happening, over the last few months I replaced the following parts:

1. New brake pads and shoes on all 4 with new hardware.
2. New rubber brake hoses in both front brakes.
3. New wheel cylinders in both back brakes.
4. New caliper with piston assembly in front driver side. Passenger side is fine.
5. New wheel bearing in front driver side (there was visible smoke from front driver wheel when it first happened). Other bearings are fine.
6. New cheap Chinese tires on all 4.
7. Bled a large bottle of new brake fluid through the system.

None of the above fixed the problem and I am running out of $$ and ideas. Any ideas what may me be causing this intermittent brake locking issue?

(This post was edited by YourMinky on Dec 4, 2017, 8:43 PM)


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Dec 5, 2017, 1:38 AM

Post #2 of 21 (551 views)
  post locked   Re: Intermittent brake locking issue diagnosis  

? You've already done all that and it does all the same things?
I'm caught up with brake pedal stuck up top and over time slowly as it cools will move more and more. That would be the master cylinder stopping pedal from moving most likely either because of it or the result of the real problem.
Sorry if missed but that wasn't replaced on your list need to know what was done before all this or happened to this car including any service as for now want to rule out brake fluid contamination is a real disaster if an OIL is added (may have been some time before any problems) along the way rubber everything swells all kinds of bizarre things can go wrong.
So you've bled it all out with new BRAKE fluid is good the evidence would still be around starting with even the rubber seal that flexes of a master cylinder's fill cap.


Let's leave engine being noisy out of this for now. Driving this long enough with SMOKE coming off of a wheel that hot can just see this scene pedal to the metal fighting locked up brakes with engine wasn't good for anything.


Look for swollen rubber at master cylinder - fluid contamination has to be ruled out IMO,


T



Discretesignals
Ultimate Carjunky / Moderator
Discretesignals profile image

Dec 5, 2017, 4:25 AM

Post #3 of 21 (543 views)
  post locked   Re: Intermittent brake locking issue diagnosis  

Next time the brakes are locked up unbolt the master cylinder with it connected to the lines from the brake booster. If the brakes release with the master unbolted, there may be a problem in the booster.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.


YourMinky
User

Dec 8, 2017, 11:08 PM

Post #4 of 21 (498 views)
  post locked   Re: Intermittent brake locking issue diagnosis  

Yes, same symptom even after replacing all those parts which I mentioned. Fluid contamination is highly unlikely. I have already flushed the brake fluid. The rubber parts look fine, nothing swollen.


(This post was edited by YourMinky on Dec 8, 2017, 11:11 PM)


YourMinky
User

Dec 8, 2017, 11:14 PM

Post #5 of 21 (494 views)
  post locked   Re: Intermittent brake locking issue diagnosis  


In Reply To
Next time the brakes are locked up unbolt the master cylinder with it connected to the lines from the brake booster. If the brakes release with the master unbolted, there may be a problem in the booster.

If I unbolt the master cylinder when it happens again, will it not have hot brake fluid oozing out and also introduce bubble to the system which would cause even more problems? Can you point me to a video that shows how to unbolt it safely?


Hammer Time
Ultimate Carjunky / Moderator
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Dec 9, 2017, 4:25 AM

Post #6 of 21 (482 views)
  post locked   Re: Intermittent brake locking issue diagnosis  

No, you are not loosening any brake lines, just the mounting bolts that attach it to the booster. It will not leak any fluid.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



YourMinky
User

Dec 10, 2017, 11:38 AM

Post #7 of 21 (455 views)
  post locked   Re: Intermittent brake locking issue diagnosis  


In Reply To
No, you are not loosening any brake lines, just the mounting bolts that attach it to the booster. It will not leak any fluid.

Thanks for your comment.
OK, next time it happens, I'll loosen the master cylinder mounting bolt so the pushrod from the booster no longer pushes the master cylinder. If the vacuum booster was the culprit then the brakes would unlock right away after loosening the mounting bolts, correct?
So, I'll also need the front of the car lifted up in order to rotate the tires, correct?
Or may be without lifting the car up I can put it in neutral and try to push the car and it should move freely, is that how to test it?
Is there any way to check the pedal for issues? What are the factory specs?


(This post was edited by YourMinky on Dec 10, 2017, 11:40 AM)


Discretesignals
Ultimate Carjunky / Moderator
Discretesignals profile image

Dec 11, 2017, 7:29 AM

Post #8 of 21 (422 views)
  post locked   Re: Intermittent brake locking issue diagnosis  


Quote
If the vacuum booster was the culprit then the brakes would unlock right away after loosening the mounting bolts, correct?

Correct



Quote
So, I'll also need the front of the car lifted up in order to rotate the tires, correct?

Yes, the brakes have to be locking up and someone needs to be trying to rotate the fronts, while you loosen the master from the booster.


Quote
Or may be without lifting the car up I can put it in neutral and try to push the car and it should move freely, is that how to test it?

That will work too.

99% of the time is won't be a pedal/rod adjustment issue as long as nobody has touched or modified it.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Dec 11, 2017, 7:58 AM

Post #9 of 21 (416 views)
  post locked   Re: Intermittent brake locking issue diagnosis  


Quote
99% of the time is won't be a pedal/rod adjustment issue as long as nobody has touched or modified it.


Although I agree with that statement, I recently had one that had a master cylinder replacement and the piston in the master was different and caused a problem with the pushrod. Even a second master replacement had the same issue. The pushrod had to be modified to correct the problem.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



YourMinky
User

Dec 11, 2017, 8:49 PM

Post #10 of 21 (405 views)
  post locked   Re: Intermittent brake locking issue diagnosis  





YourMinky
User

Dec 11, 2017, 8:59 PM

Post #11 of 21 (401 views)
  post locked   Re: Intermittent brake locking issue diagnosis  

I still have the original MC and pedal and no one adjusted those ever (photo above). My vacuum booster also has a proportioning valve attached to it. Can I remove the MC without having to remove the proportioning valve (photo attached above). There is no way to remove the vacuum check valve and test it as it seems like built-in (photo).
Now the brakes lock every time I drive the car for a few miles. The front driver side lug nuts gets sizzling hot. The front passenger side is always not as hot. Back side is always not hot. The brake gets so sensitive that the car stops as soon as I touch it without even having the pedal to travel far enough to activate the brake light switch.
Can a warped rotor on the front driver side causing this lock?
I tested the vacuum by pressing the brake pedal several times with the engine off and then holding the pedal down. Then I turned the engine on. The pedal goes down fine when the engine starts and creates the vacuum.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Dec 11, 2017, 9:20 PM

Post #12 of 21 (396 views)
  post locked   Re: Intermittent brake locking issue diagnosis  

You've got the same question going on another site. Let's see how you make out there.

You were given the answer very early in both questions and still have not followed instructions.

https://www.2carpros.com/...kes-seizing-on-front



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



YourMinky
User

Dec 11, 2017, 9:59 PM

Post #13 of 21 (390 views)
  post locked   Re: Intermittent brake locking issue diagnosis  

 
I beg your pardon. I did not receive any definitive answer. I followed the recommendations several times and replaced many parts so far but the problem is still there.
No one EVER adjusted the pedal or the pushrod on my car. Can they automatically lose adjustment after 17 years?


YourMinky
User

Dec 11, 2017, 10:01 PM

Post #14 of 21 (388 views)
  post locked   Re: Intermittent brake locking issue diagnosis  


In Reply To
..........You were given the answer very early in both questions and still have not followed instructions.
..............]

I beg your pardon. I did not receive any definitive answer. I followed the recommendations several times and replaced many parts so far but the problem is still there.
No one EVER adjusted the pedal or the pushrod on my car. Can they automatically lose adjustment after 17 years?


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Dec 12, 2017, 6:15 AM

Post #15 of 21 (380 views)
  post locked   Re: Intermittent brake locking issue diagnosis  

Really? Have you loosened the mounting bolts of the master cylinder as you were advised real early in both forums?



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



YourMinky
User

Dec 13, 2017, 9:03 PM

Post #16 of 21 (363 views)
  post locked   Re: Intermittent brake locking issue diagnosis  


In Reply To
Really? Have you loosened the mounting bolts of the master cylinder as you were advised real early in both forums?

I posted a question related to removing the MC mounting bolts and no one answered.
There is a bracket that connects to another valve (which is also bolted on the vacuum booster) with the MC. When the locking happens again, do I have to loosen any lines? It looks like just removing the MC mounting bolts wont be enough (see photo), the bracket wont let the MC to move.



(This post was edited by YourMinky on Dec 13, 2017, 9:34 PM)


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Dec 14, 2017, 1:58 AM

Post #17 of 21 (338 views)
  post locked   Re: Intermittent brake locking issue diagnosis  

Appears that's a proportioning valve also looks like it would come forward is loosened but now with a pic that's borderline corroded enough to be breaking lines or the nuts holding that bracket to booster.
There should be enough flex like a long section of line or coil not seen to allow some motion you aren't looked for a lot. The idea is in effect you are shortening the pushrod some - understand that? If brakes were sticking perhaps even without removing those nuts just backed off 1/8th inch they would release.
Strong suggestion here because of that corrosion is to put some PB in a cap (good plastic cap to something you are not using) and with a Q-Tip wet the threads now exposed and would also wet the lines to the flare nuts is where those can stick and twist if ever removed also the threads. That stuff has to sit a while IMO on that would work just be prepared to make up those lines if needed and not sure where the studs or how then are fixed to the booster could require a new booster if you bust those off?
IMO those are marginal, items down the line from that will be worse hit those now you may be doing more than some adjustment like making up lines right on thru to bleeders tend to that stuff now or periodically you will be or someone doing more make that easier now,


T



Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Dec 14, 2017, 3:12 AM

Post #18 of 21 (334 views)
  post locked   Re: Intermittent brake locking issue diagnosis  

If you can't figure out how to move that master away from the booster, then you really shouldn't be trying to fix this.

That proportioning valve won't prevent you from moving the master 1/4inch.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



(This post was edited by Hammer Time on Dec 14, 2017, 3:14 AM)


YourMinky
User

Dec 17, 2017, 12:53 PM

Post #19 of 21 (304 views)
  post locked   Re: Intermittent brake locking issue diagnosis  

Some of you suggested that I unscrew the brake line when the brakes lock to see if that releases the lock. That will tell whether the MC is not taking back the fluid through the compensating port. To test this, do I unscrew the brake line at the MC or at the proportioning valve? Will it have the same effect if I open the bleeding screw at one of the front wheels? I have sprayed PB-Blaster on all screw mounts as suggested.
I haven't driven the car lately but I was able to use PB-blaster and safely unscrew the MC mounting bolt from the booster. The proportioning valve was attached to the bracket, so it moved as well. I'll drive the car today or tomorrow and if it locks, I'll unbolt the MC and give it about 1/4 (quarter) inch slack for a minute and then bolt it back and report back to you guys.
BTW, I flushed the brake fluid and bled all four brakes yesterday. Existing fluid color was fine, not dark or rusty.
I'll keep you posted.


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Dec 17, 2017, 1:08 PM

Post #20 of 21 (302 views)
  post locked   Re: Intermittent brake locking issue diagnosis  

I would have suggested just loosening a brake line WHEN it's locked just enough to see pressure come out. Same deal with moving master cyl. forward is checking to see if it thinks it's being pushed on by pushrod but isn't that moves it away for fluid to return if not back to the brake line or better yet a bleeder leave those alone at the master and valve for now.


Gotta target where it's locking up pressure is the whole idea it shouldn't be of course and will wreck your brakes or worse,


T



Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Dec 17, 2017, 1:25 PM

Post #21 of 21 (298 views)
  post locked   Re: Intermittent brake locking issue diagnosis  

 

Quote
Some of you suggested that I unscrew the brake line when the brakes lock to see if that releases the lock. That will tell whether the MC is not taking back the fluid through the compensating port.

No, that is not what was suggested at all.

It was suggested to crack the line at the wheel and all that tests is the wheel, not the master. You were advised long ago how to check the master and you either don't want to or don't know how. This thread is just going in circles now. You are posting on another site and getting all kinds of wrong advice and even they circled back to the same advice you were given in the beginning.

You aren't taking the advice and you keep coming back totally sidetracked so this thread has run it's course and I'm going to close it now.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.







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