1998 abs brake bleed

Discussion in 'Chevy Truck Forum' started by lcarroll, Aug 20, 2013.

  1. lcarroll

    lcarroll Member

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    Help I have replaced the whole brake system minus the brake lines & the abs.I cannot bleed the brakes.When you wait about 30 minutes you have as much air in the right rear as you did when you started.I am going to replace the abs next.Any help would be great!!!
     
  2. dirtrider73068

    dirtrider73068 Senior Moderator
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    Air is getting into the system somewhere could be a loose fitting.
     
  3. chevychase

    chevychase Semi-Admin
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    Probably have to have a scan tool to control abs module open/close..these can be a pain to bleed. Only other way if you can get good enough pedal
    Can go down road hit brakes hard..to activate abs module the bleed...gravel road is the best to activate.
    You replaced lines you have air in the abs module...probably need to just get a tech 11 scan tool or take to a garage ..be done ??
    If abs module has air you will bleed till the cows come home..still not get brakes .
    This will give you some ideals https://www.google.com/search?q=98+...iv2QXdsYDQCg&ved=0CAwQ_AUoAA&biw=1280&bih=852

    Might find better vids on this just type in your query at search youtube.
     
  4. gpmorgan

    gpmorgan Auto Banned

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    This is some info from AutoZone.
    Bleeding the ABS System

    Print
    The brake system must be bled when any brake line is disconnected or there is air in the system.
    Never bleed a wheel cylinder when a drum is removed.
    1.Clean the master cylinder of excess dirt and remove the cylinder cover and the diaphragm.

    2.Fill the master cylinder to the proper level. Check the fluid level periodically during the bleeding process, and replenish it as necessary. Do not allow the master cylinder to run dry, or you will have to start over.

    3.Before opening any of the bleeder screws, you may want to give each one a shot of penetrating solvent. This reduces the possibility of breakage when they are unscrewed.

    4.Attach a length of vinyl hose to the bleeder screw of the brake to be bled. Insert the other end of the hose into a clear jar half full of clean brake fluid, so that the end of the hose is beneath the level of fluid. The correct sequence for bleeding is to work from the brake farthest from the master cylinder to the one closest; right rear, left rear, right front, left front.

    5.The combination valve must be held open during the bleeding process. A clip, tape, or other similar tool (or an assistant) will hold the metering pin in.

    6.Depress and release the brake pedal three or four times to exhaust any residual vacuum.

    7.Have an assistant push down on the brake pedal and hold it down. Open the bleeder valve slightly. As the pedal reaches the end of its travel, close the bleeder screw and release the brake pedal. Repeat this process until no air bubbles are visible in the expelled fluid.


    Make sure your assistant presses the brake pedal to the floor slowly. Pressing too fast will cause air bubbles to form in the fluid.
    8.Repeat this procedure at each of the brakes. Remember to check the master cylinder level occasionally. Use only fresh fluid to refill the master cylinder, not the stuff bled from the system.

    9.When the bleeding process is complete, refill the master cylinder, install its cover and diaphragm, and discard the fluid bled from the brake system.

    10. Perform 3 function tests with the TECH 1 scan tool. The brake pedal must be firmly applied.

    11.On models with rear wheel ABS:
    A.Refill the jar with clean brake fluid and attach the bleed hose to the bleed valve on the Isolation/Dump valve.

    B.Have your assistant slowly depress the brake pedal and hold it. Loosen the bleed valve and expel the air. Tighten the valve and slowly release the pedal.

    C.Wait 15 seconds and repeat this procedure. Repeat bleeding the Isolation/Dump valve until all the air is expelled.



    12.On models with 4 wheel ABS, repeat Steps 1-9.
     
  5. MrMarty51

    MrMarty51 Full Member

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    4WAL is a sort of a seperate unit from the "Foundation" brakes. In other words, if the ABS system fails, You will still have brakes, just like a vehicle without ABS.
    Now, keeping that in mind, the brake bleeding sequence is the same as an older vehicle, without ABS.
    I did`nt know that about the 2WAL or rear anti lock brakes, I have just bled them like a normal, regular, brake system. :rofl:
    Did`nt know that about the combination valve either. seemed to bleed out like there was nothing restricting anything at all. :rofl:
     
  6. lcarroll

    lcarroll Member

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    Nothing else has worked Im going to take it to someone with a scan tool!!!!!!!!!
     
  7. lcarroll

    lcarroll Member

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    But thanks to all of you for your help Lanniec
     
  8. chevychase

    chevychase Semi-Admin
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    Your mighty welcome lanniec..wish you the best of luck..these can be a pita!!!
     

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