Mechanics

BRAKE LOCKUP ON 1 WHEEL

1999 Jeep Cherokee

Brakes problem
1999 Jeep Cherokee 6 cyl Four Wheel Drive Automatic 123685 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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Lwshockley
November 24, 2008.



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.

Tiny
Mastertechtim
Nov 25, 2008.
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?

Tiny
Lwshockley
Nov 25, 2008.
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.

Tiny
Mastertechtim
Nov 25, 2008.