2009 Chevrolet Uplander brake issues

  • 68,000 MILES

About 5 weeks ago I took my van in for it's semi-annual inspection. I also told them I was having brake pedal issues. After inspecting they found the rear pads needed replacing, and rotors needed machining. I authorized them to do the work. Took it for a test drive and the pedal was still not right. After some diagnostic test there were no codes. The mechanic took it for another drive with a portable diagnostic machine and it coded inoperative electronic brake and traction control. Diagnostic chart recomended replacing BPMV valve and EBCM. After replacing these parts they bled the lines, topped off brake fluid and road tested ok. Also they did a brake through service, I'm wondering what all they did with that? We went on holidays for a couple of weeks and I noticed the brake pedal was still not functioning properly. There were a lot of hills were we were and over a couple weeks the pedal would go almost to the floor while braking downhill. On flat ground it would be very hard to push. Infact the brakes had failed completely while my Mom was driving down the hill with my niece. She had to make a quick right turn onto someone's property to avoid a collision with trees and a building, never mind the potential to go off a cliff! As you can imagine I did not want to drive the van, my brother was visiting and drove it home for me safely. I then had it towed to the dealership. I am now waiting after 3 days of being in to see what is going on. They first told me the brake fluid is contaminated and would have to replace all components with rubber on them. Now they are waiting 4-5 days to test it, and if it's not contaminated they say it's the master cylinder that will need replacing. My question is if it is contaminated would they not be the ones responsible for that since they were the last ones to service my brakes? Is there anyway to hold them accountable for that? From the research I've been doing it would not take long for the damage to occur. I've been living here for a year and no one else has worked on my van. My mileage is 68000 km. Thanks in advance for any info.

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Thursday, August 1st, 2013 AT 6:36 AM

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One thing that is correct is if the brake fluid is contaminated with a petroleum product every part that has rubber that contacts the fluid must be replaced at the same time, and all the steel lines must be flushed and dried, THEN all the new parts can be installed. That is always a very expensive repair and it's much worse on GM vehicles with anti-lock brakes. If any one or more parts are not replaced the contamination will leach out of the rubber and recontaminate the new brake fluid.

One clue you can look for yourself is to remove the cap on the brake fluid reservoir and inspect the rubber bladder seal. If it is blown up and mushy, that is a sign of contamination. If the amount of contaminant in the system is significant the symptoms will show up in less than a week, and often in a few days. As disc brake pads wear, the self-adjusting feature causes the fluid level to drop in the reservoir. That will usually pull that bladder seal down out of the cap. When people check the fluid level, like during oil changes or other routine service, they will typically pop that seal back into the cap. If there is grease on their fingertips, the fluid just became contaminated. Brake system specialists and other experienced mechanics will even wash their hands to remove excess fingerprint grease before working with brake fluid components.

I was recently involved as an impartial observer of a case of contaminated brake fluid that involved a very intelligent and reputable shop owner and my very conscientious former student who learned a lot from me about preventing fluid contamination. The problem you are going to have is proving no one else worked on the vehicle or had the opportunity to introduce the contamination. That can include carelessness at the dealership or sabotage at a quickie oil change place. Your other problem is you noticed a brake pedal problem before you took it in for service. To me that suggests a defective master cylinder or some other problem other than fluid contamination. Most commonly contaminated fluid results in a brake pedal that is hard to push, doesn't move very far, and the brakes will stay applied and self-apply harder as they get hot. It's kind of doubtful, but not unheard of, that you could have driven more than a few dozen miles with contaminated fluid.

The mechanic also needs to consider a failure in the anti-lock brake hydraulic controller. There have been reports years ago on GM trucks with the brake pedal intermittently going to the floor, and in one case the guy sailed through a red light, luckily harmlessly, then the pedal was fine again moments later. I never did learn what the outcome with that one was.

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Thursday, August 1st, 2013 AT 11:42 AM

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