QuestionQUESTION: Hello, here is my question. I will try to make this easy to understand and quick, Back brake needed new pads, my brother replaced the back brakes but could not bleed the driver side. I was getting brake but then it would go to the floor to a stop. I took the car into a mechanic and he replaced the Master Cylinder. He told me that the proportioning valve would not bleed and he tried many times to blow it out. He said that he would only get the rear brakes to work 25 percent of the time. He told me to drive the car, that I would be running on my front brakes but I will be able to stop. I drove the car one day and now I have no brakes again. The peddle is going right to the floor. I am able to pump but after release, it goes right to the floor again. I am questioning if it was the master cylinder at all. The brakes before the cylinder, it would slow to go the floor during a stop * which sounds like the cylinder* I was talking to my brother and he informed me that he believe that there was a brake leak that might have contributed to the master cylinder going bad. Now if this is the proportioning valve then I was also informed that it was 185.00, must be from Hyundai. Can I get this cheaper at an auto supply store? The master cylinder he charged me was 185.00 itself, which I have seen on the net for $115.00. Can someone give me some insight? Also is the proportioning valve easy to replace with little labor?
ANSWER: First and foremost, do not drive this vehicle. Second, I cannot recommend returning to the facility that replaced the master cylinder. No competent and honest repair facility would imply to you that there is no safety hazard with brakes that are not fully operational.
At this point, I'm unable to get into specifics about your brake system without a little more information to enable me to know what brake components you have on your vehicle. Here's what I need to know:
1. Year and model of your vehicle.
2. Whether your vehicle is equipped with ABS.
3. Depending on your year and model, whether your rear brakes are disc or drum.
I'm also curious why your brother was trying to bleed the brakes. Normally, pad or shoe replacement doesn't require bleeding the system.
With the history of your problems and work on the vehicle, the system will need to be systematically diagnosed. If there's a blockage in the system, it's important to find out where it is. First, check to see which wheels have brake fluid pressure. Then for any that don't have pressure, start with the lines at the master cylinder for those wheels. Check to see whether fluid is present at the master cylinder. Then, systematically, move down the brake line to the next joint, and try again. When you get to the point where there's brake fluid pressure at one joint but none at the next, you've found the section that has the problem.
If you again take this car to a repair facility, be forthcoming with the information you've given me about what has been done and what has happened each time. This will be very important for the facility in determining what diagnostic approach they will need to take.
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QUESTION: Thanks for getting back to me. I believe that he replaced the calipers. My car is a Hyundai elentra 2000. I do not have ABS. I agree with why he actually said drive the vehicle. Do you think the master cylinder was at all at fault? Since its acting the same way I question that. I am very leery of mechanics these days. I cannot seem to find an honest one. I have been taken and taken and no one has fixed my issues without me getting help from you experts. I have actually found out the problems and fixed everything myself by telling them what to repair. When my brother bled the back brakes he was getting fluid to the driver side and front only. The front brakes were running fine. I checked the fluid " tank above the master cylinder?" and that is full. Do you think what he is saying the proportion valve is the cause? Do you know any good mechanics in the Aurora/Chicago Area? lol. Thanks so much for your help. I appreciate it.
ANSWER: Unless my memory serves me incorrectly, the 2000 Elantra has rear drum brakes unless it has ABS. If you indeed have rear drum brakes, then there would be no calipers in the rear to replace. At this point, I'm not sure this is of any significance to me, though.
If your car is indeed doing the same thing now that it was doing previously, then it's doubtful the master cylinder was the issue. The proportioning valve is a possibility, but again, a good systematic diagnosis is needed to be sure.
I doubt the issue is lack of honesty. More likely, it's a lack of knowledge of operating principles and/or diagnostic procedures.
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QUESTION: oh my brother said that he changed the cylinders.
AnswerReplacing the wheel cylinders would indeed require bleeding the brakes.
Sometimes, when replacing wheel cylinders, the metal brake line seizes to the fitting, causing the line to twist shut when the fitting is turned to remove the line from the wheel cylinder. It's a good idea to perform a visual inspection of the brake system (especially the brake lines in this case) prior to beginning more complicated diagnoses.
