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Brake problems on a 2008 Kia Sorrento
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hamblinb
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Nov 18, 2022, 11:33 AM
Post #1 of 4
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Brake problems on a 2008 Kia Sorrento
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I've got a 2008 Kia Sorrento 3.3L engine, with ABS, that my wife usually drives. One day I jump in it to move it and found a soft pedal. Her response is "it's been that way for a long time". So, I'm trying to deal with fixing it. I changed out the master cylinder and found there was some brake fluid in the throat of the brake booster. I wiped up the brake fluid by the booster. After bleeding, the brakes are still soft. And I'm not sure that they've really changed much at all. When I tried to bench bleed the master cylinder, i added the fluid to the max line and waited for it to slowly leak out of the two small port holes. I then threaded in the plastic threaded plugs that came with it. Then I started the process of pushing the plunger with a blunt screwdriver. I could only get the cylinder to depress about 3/16" and it was solid, I tried a couple of times, but couldn't get it any further. Then I installed the master cylinder. So potentially, I didn't try hard enough to push in the master cylinder during the bench bleed? And there's still air in the master cylinder? If so, wouldn't it have been eventually bled out through the ABS module, through the brake lines, and out the caliper bleeder, using my hand-held vacuum pump? Now I've read online that air bubbles can become trapped in a high spot in the brake lines. And this vehicle has quite a few of them. One site suggested moving lines around to allow any air bubbles to move toward the caliper. For this vehicle I would have to completely remove the brake lines. Is that truly necessary? If so, what if I replaced the entire brake line, it would be full of air, until you start bleeding the brakes, but those high spots, would then be impossible to get the air out, wouldn't it? I've heard of the pros using a special vacuum tool that attaches to the master cylinder cover and sucks the air out that way. I wonder if I could use the old master cylinder cover, drill a hole in it to match the hose of my hand-held vacuum and I could do the same thing? Regarding the bleeding of the brakes, I bought a hand pump vacuum system and made sure to maintain at least a 10" w.c. negative pressure when I was bleeding the brakes. It was difficult to see if there was any air in the lines, as air will suck in on the sides of the threads of the bleeder valve. I then had my son in law come over with a friend. He has the cheaper variety where the container is held magnetically, while a second person pumps and holds the brakes. No more air bubbles were seen in the clear tubing. One thing that I'm considering is replacing the brake booster, as one site said that could be the issue. Now as I said, the master cylinder had allowed some brake fluid to go into the throat of the brake booster, which could have caused some issues in there. But if the diaphragm was compromised from the brake fluid, I would expect the brake pedal to be very hard to press, not easy? With a broken diaphragm, I wouldn't expect to get much of a pressure difference across the diaphragm, which should create a very hard brake pedal. I don't want to drop $300 on a reman brake booster (new aren't available anywhere by me), only to find out it wasn't the issue. Any help is appreciated.
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Hammer Time
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Nov 18, 2022, 11:55 AM
Post #2 of 4
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Re: Brake problems on a 2008 Kia Sorrento
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I don't know where you got your instructions on brake bleeding but vacuum bleeding is not the preferred way to bleed. The best way to bleed is with a pressure bleeder on the master cylinder and the second best is with a helper pumping and holding the brake pedal while you open the bleeder. Forget that nonsense about air getting stuck in lines. That doesn't happen when bled correctly. Now, the big problem you have is this will likely require electronic bleeding using a bidirectional professional scan tool. Otherwise air gets trapped in the ABS unit. My suggestion is have it professionally bled by a shop that has the right equipment. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 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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hamblinb
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Nov 18, 2022, 1:46 PM
Post #3 of 4
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Re: Brake problems on a 2008 Kia Sorrento
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Does it need to be bi-directional for bleeding the ABS system? I am seeing some cheap Autel OBD readers on Amazon. It sounds like they do the auto bleeding.
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Hammer Time
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Nov 18, 2022, 1:49 PM
Post #4 of 4
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Re: Brake problems on a 2008 Kia Sorrento
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Yes, of course. You are not receiving data, you are sending it to initiate a sequence from the ABS module. Edit, I see the units you are referring to. They state they any work on certain models. You can get it professionally bled cheaper than that. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 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 Nov 18, 2022, 1:59 PM)
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