Spongy brakes

Discussion in 'CRD KJ's Section' started by Lacey, Oct 13, 2019.

  1. Lacey

    Lacey New Member

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    I have a 2005 liberty CRD with spongy brakes. Im sure it was a gradual change but i noticed it back in june and stopped driving it in July because of how bad it was and I wasnt comfortable driving it with the kids. My husband is a diesel mechanic and we have done everything possible to fix this problem and we just replaced all the brake lines with stainless steel braided hoses and there has been no change. He has replaced everything except the vacuum booster. Everything. Calipers, brake pads, master cylinder and all brake hoses. The pedal is nearly all the way in before it actually does what it is suppose to do. I love my jeep and planned on driving it until the rust claimed it. Now im stuck driving the mini van. What are we missing? Please help!
     
  2. Billwill

    Billwill Full Access Member

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    The CRD has a vacuum pump driven by the Serpentine Belt.
    This pump supplies vacuum to the vanes on the interior air flow controls to direct air flow but also has a rubber pipe going to the vacume booster.

    Check that this hose is connected at both ends with no cracks.

    Otherwise you may need a Brake Shop to check that there is no air in the system and to check the Booster is working.
     
  3. Lacey

    Lacey New Member

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    Thanks for the response! My husband says he checked the hose and it was fine. He removed it to make sure the was suction and it was working as it should. He wanted me to ask if there is a way to bleed air from the front abs pump unit because there is no bleeder port?

    We dont believe the vacuum booster is bad. My research and.my husband tell me that the brake will be very stiff if the vacuum booster is bad and this problem is completely opposite.
     
  4. Billwill

    Billwill Full Access Member

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    Generally the way to test the Brake Booster is as follows...I cannot check this myself on my 2002 Export 2.5 CRD as it is not with me at the moment but I am sure other Owners here will chip in!

    With the Ignition OFF press the brake pedal down and hold it in this state with reasonable firmness.

    Now turn On the ignition and start the Jeep while holding the pedal down.

    After a few seconds you should feel the brake pedal drop a bit under your foot pressure but should still be firm...this indicates that the Brake Booster is working...dropping a large amount is not good!

    The Master Cylinder could also be at fault.

    Best to download the Jeep KJ Service Manual for your 2005 KJ here:

    www.colorado4wheel.com/manuals/Jeep/KJ/

    You can read up the theory of Operations on all the components such as the Braking System and ABS.
     
    Last edited: Oct 15, 2019