Problem with the front brakes locking and overheating

Tiny
NDAN598
  • MEMBER
  • 2000 JEEP CHEROKEE
I have had a problem with the front brakes locking and overheating for about 8 months now. There have been no brake warning lights to come on and no error codes in computer. It does not happen every time you drive but it has gotten much worse over time. Mechanic has replaced pads, brake lines, master cylinder, calipers, bled the system and turned the rotors. The last time only the left front locked up. You could feel a pulsing sensation in the brake pedal and then locked. The time before that, both front brakes locked and it had to be towed. Any ideas?
Wednesday, February 3rd, 2010 AT 1:19 PM

15 Replies

Tiny
MERLIN2021
  • MECHANIC
  • 17,250 POSTS
This happens when the brake booster push rod is adjusted out too far which does no allow the brake master to return fully holding the brakes on. To confirm the issue loosen the brake master mounting bolts 3 turns to see if the car starts to roll again, if so remove the master and adjust the booster push rod inward. Also a brake flex hose can come apart internally causing a short of check valve in the system but this is usually isolated to one brake either front or rear.

Drive it till it starts to bind or you notice drag, jack that wheel up, chock the rear wheels, put it in neutral, does the wheel spin, if not or it's hard to turn, open the bleeder screw, does it spin freely now? If yes, replace the flex hose, I recommend doing the same work to BOTH front brakes, this will eliminate any issues with pulling to one side! Also both fronts are the same age and condition, if you don't do both now, you will real soon.
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Wednesday, February 3rd, 2010 AT 1:24 PM
Tiny
MRBSOC129
  • MEMBER
  • 1 POST
  • 1999 JEEP CHEROKEE
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 139,000 MILES
Yesterday I replaced my front brake pads and rotors and bled the front brake lines. When I went to give it a test run, I popped it in gear and it sat there, as if still in park. Hit the gas a little, and felt that the front passenger wheel was locked up. I took everything off the front passenger again to make sure I installed everything properly the first time--looks like I did. After putting everything back on, the same thing happened. Today I replaced the front passenger caliper, thinking maybe the old brake pads were so worn down that the first caliper's pistons were shot. After installing the new one, the same thing happens. Any ideas? Thanks.
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Thursday, May 20th, 2021 AT 10:15 AM (Merged)
Tiny
TOOOMANYTOYS
  • MECHANIC
  • 513 POSTS
When you did the brakes are you sure the caliper didnt get twisted causing a kink? Sometime the brake hose if kinked can cause brake fluid to flow out but not back in.
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Thursday, May 20th, 2021 AT 10:15 AM (Merged)
Tiny
LWSHOCKLEY
  • MEMBER
  • 2 POSTS
  • 1999 JEEP CHEROKEE
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 123,685 MILES
I own a quick lube and performed an oil change on the above vehicle last Spring. Within a couple of hours, the customer called back saying he had a problem - his Jeep would not move. We sent a lube tech to check it out. He found that his brakes had locked up on one wheel. We told the customer the problem was not related to our oil change service and he called a tow truck and took it to a repair shop, which said his brake fluid was contaminated with some petroleum as the master cylinder seal was swollen and deformed. He also said this same repair shop had redone his brakes a year earlier because of a similiar problem.
He believes we added oil or power steering fluid to the brake fluid reservoir. We responded that we never ever add anything to brake fluid reservoirs. We only check the fluid level by looking through the translucent side of the reservoir. We never take the lid off unless the reservoir is NOT translucent, which is rare. Also, we informed the customer that we have NO brake fluid in our facility, so we can't even add any if it is low. We also informed the customer that IF we had accidentally added something to his reservoir, there would not have been enough time since he left our shop for the fluid to have badly deformed his reservoir seal and caused a brake to lock up. He doesn't believe us and is sueing us in small claims court for the $1,100 he paid to have his brake system replaced AGAIN.

Do you concur that even if we had added a petroluem product to his reservoir by accident, that the damage he says was caused could not have happened in less than a day? If so, why OR If not, why do you feel the way you do? Also, what causes a brake to lock up and how long does it take to happen? Any thoughts as to what caused his problem?
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Thursday, May 20th, 2021 AT 10:15 AM (Merged)
Tiny
MASTERTECHTIM
  • MECHANIC
  • 4,749 POSTS
In my experience it takes a long time for the brakes to be affected by oil in the system. What actually was replaced? The oil will swell all the rubber seals. Its unlikely it happened from him driving away from your shop and brakes locking up down the road, I would think it would have been done at the previous oil change is more likely. This is going to be a tough one to prove in either way. If he takes his car to your shop religiously for oil changes who does the regular maintainance? It could have happened there. Your in a tough spot. I have benn repairing cars for about 20 years and have never had to replace a entire brake system for contaminents in it, usually fklushing the system and possibly a new master cylinder because that is where the contaminated fluid is. Remember brake fluid does not circulate through the master cylinder. The brake fluid that is in the lines and at calipers and wheel clinders is the same fluid so there is no way for the contaminated fluid to get to the ends. I hope this sheds some light and maybe some of the other techs can add something.
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Thursday, May 20th, 2021 AT 10:16 AM (Merged)
Tiny
LWSHOCKLEY
  • MEMBER
  • 2 POSTS
The Jeep had the following repair done for $1100: remove and replace the master cylinder, both front calipers and both front brake hoses. Our quick lube had only serviced the Jeep once before and that was 21 months and 30,000 miles earlier. I know that petroleum in the brake fluid will cause the seals to swell, but even that couldn't occur significantly in two hours or less, could it? Also, what conditiion or conditions are likely to cause a brake to "lock up" or drag? If I understand you correctily, any contamination in the master cylinder reservoir would be confined to that area only for some period of time, presumably far longer than a couple of hours. Actually, I think our customer called us within 30 minutes or 1 hour. A final question: Are you ASE certified in brake repair?
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Thursday, May 20th, 2021 AT 10:16 AM (Merged)
Tiny
MASTERTECHTIM
  • MECHANIC
  • 4,749 POSTS
Im ase certified master. No way in my opinion could you have caused it. The fluid does not flow through the hoses. It uses pressure in a short distance to push pistons in and out. The fluid is contained in master cylinder and possible the first inch of the brake line, especially in that short of time there is no chance to get out to the calipers. I would think that if it was contaminated that its nearly impossible for your shop to have caused it due to the swelling being apparent so fast.
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Thursday, May 20th, 2021 AT 10:16 AM (Merged)
Tiny
JIMMY BALTAZAR
  • MEMBER
  • 1 POST
  • 1998 JEEP CHEROKEE
  • V8
  • AWD
  • AUTOMATIC
  • 112,000 MILES
Front left caliper keeps on sticking. I've replace rotors pads top dollar pads caliper twice brake line from caliper and finally brake equalizer
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Thursday, May 20th, 2021 AT 10:16 AM (Merged)
Tiny
CARADIODOC
  • MECHANIC
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How do you know it's sticking?

My first guess would have been the brake hose since you already replaced the caliper. Rebuilt calipers, right? Not used ones?

Next time it sticks, open the bleeder screw, then see if it releases. If it does, suspect petroleum fluid contamination. See if the rubber seals under the master cylinder caps blow up and are mushy. If this is the case, you will need to replace everything with rubber in the hydraulic system, and flush and dry the steel lines.

Caradiodoc
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Thursday, May 20th, 2021 AT 10:16 AM (Merged)
Tiny
INKEDONE
  • MEMBER
  • 3 POSTS
  • 1998 JEEP CHEROKEE
  • 170,000 MILES
It need brakes, so went to collapse, both calipers would not copress, so iput in new pads rotors and calipers, test drove it they would buildup and bindup after 20 mins of driving, so figured bad rubber lines. So replaced them, nope still building and binding after a test drive, only way to release the pressure to drive it is to crack the bleeders Cant figure it out please help me
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Thursday, May 20th, 2021 AT 10:16 AM (Merged)
Tiny
CARADIODOC
  • MECHANIC
  • 33,728 POSTS
Well, you're three steps ahead of most people by understanding the rubber hoses and opening the bleeder screws. Next, when this happens again, loosen the steel lines at the master cylinder. If the brakes release there suspect the brake fluid is contaminated with a petroleum product. That would be real bad news.

Do you have anti-lock brakes?
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Thursday, May 20th, 2021 AT 10:16 AM (Merged)
Tiny
INKEDONE
  • MEMBER
  • 3 POSTS
I do not think I have abs no sensors on braking system, and if they are not contaminated what next?
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Thursday, May 20th, 2021 AT 10:16 AM (Merged)
Tiny
CARADIODOC
  • MECHANIC
  • 33,728 POSTS
The idea is to find the point closest to the master cylinder that lets the trapped fluid release. If there's no chance the fluid is contaminated but the brakes release when you loosen the lines at the master cylinder, something is holding the master cylinder applied. You can verify that the next time by loosening the mounting nuts for the master cylinder and moving it forward 1/8". If that works, check the adjustment of the brake light switch.
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Thursday, May 20th, 2021 AT 10:16 AM (Merged)
Tiny
ASH824903
  • MEMBER
  • 1 POST
  • 1996 JEEP CHEROKEE
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 250,000 MILES
I have a XJ cherokee I have renewed the front disc pads, the rear wheel cyls and shoes have been renewed about 14 weeks ago, the problem I have is under more than average braking, the rear brakes lock up, under normal braking it seems the front are not working as they should be. Can some one help with some info, Thank you.
Ash824903
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Thursday, May 20th, 2021 AT 10:16 AM (Merged)
Tiny
2CARPRO JACK
  • MECHANIC
  • 11,533 POSTS
That may be caused by shoes that are remanufactured, when they re-arc the backings they dont get the right amount on it and the shoe makes too much contact with the drum surface. Drums that have been machined and are now too large in diameter can cause the same problem, what kind of rear shoes did you use? Did they machine the rear drums? Remember cheaper parts are exactly that.
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Thursday, May 20th, 2021 AT 10:16 AM (Merged)

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