Mushy brake pedal

Discussion in 'KJ General Discussion' started by Discus, Aug 20, 2019.

  1. Discus

    Discus New Member

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    Hi, i replaced the rear rotors and pads and usually you pump the pedal afterward and the pedal get stiffer again. This time, the pedal got a bit better but still have to push too far before it gabs. The jeep was parked for a 4-5 months prior the change the rack and pinion, the wte pump and the brakes. Any idea why the pedal goes so far? Air in the libes shouldn't just appears....
     
  2. timg

    timg New Member

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    classic sign of air in the lines, if you ask me. check the fluid level at the master cylinder. if it's low you may have just pushed air into the lines. it's also possible the cylinder piston seals are damaged and leaking or letting air in. they could have stuck to the cylinder walls from sitting, and if they are old may have torn when you moved them around either taking the rotor off or putting on the new one
     
  3. turblediesel

    turblediesel memberable

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    ABS? I had to bleed my lines coming from the ABS module at the module when I changed my rear calipers. Re-bled them at the wheels after that and my mush was gone.
     
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  4. Discus

    Discus New Member

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    Never bled from the ABS module.... Will research out. I was about to just try to bleed them at the wheels.
    Thanks
     
  5. JasonJ

    JasonJ Full Access Member

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    How old is the brake fluid? Supposed to be changed fully every 2 years or 24k miles. For a reason. Almost no one ever does this. Even if you have the newest model year KJ made, that fluid could be up to 12 years old. The fluid is hydrophilic and will absorb moisture from the air (and yes, there is air that can get under the master cyl fluid cap, especially over many years)... that moisture-water, does not resist compression like the brake fluid does. That leads to a soft, mushy brake pedal feel.
     
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  6. Discus

    Discus New Member

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    Not sure how old it is. It's the brother in law's jeep. I bled them yesterday for as long as it took to get new (much lighter) fluid coming out. They are better but still a bit soft I think. I have to check that "bleeding from the ABS"
     
  7. daves06lrenegade

    daves06lrenegade Full Access Member

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    Hi Discus...
    I have a 2006 KJ that was totalled/salvage because of the past owner's improperly rerunning the driver rear brake line... It got tangled up in the front drive shaft...brake fluid then drained onto the catalytic converter and there was a drive shaft tunnel fire... After replacing transmission sensors and that wiring harness, 4wd shift lever, carpet, center console, it was once again a running Jeep... The brakes AND ABS required bleeding as like you said they were mushy... To properly bleed the lines and the ABS unit I found that it required a separate "controller" to exercise the ABS module... or visit the "dealer"... My local Chrysler/Jeep dealer wanted to charge a "diagnostic" fee and also wanted a fee to bleed the brakes... I found that an "ANCEL AD610 OBDII/ABS/SRS unit available on Ebay would do the job and it did it properly... They cost $109 with free shipping... Less than half the amount the dealer wanted to charge...

    You need to "find" the ABS bleed function and it's location is not very clear in their menus...
    1 goto "Control Units"
    2 select "Chassis"
    3 select "Misc Functions"
    4 select "Bleed Brakes"
    5 select "Initialize ABS"
    The menu will tell you which brake line bleeder location to loosen...
    I ran this procedure 3 times and my brakes are rock solid...
    Yes... It's another "tool" you gotta buy but it also does OBDII and SRS (airbag diagnosis)... It's worth buying... I don't regret it... and I have also used it on my "salvage" 2016 Chrysler 200s and my wife's 2014 KIA Optima (was also salvage)...
    Dave
     
    Last edited: Aug 22, 2019