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  1. #11


    After bleeding the system yet again...

    I searched on the internet for other possible causes of the spongy brake.The proportioning valve seems to be working,when you push the pedal in,a small brass coloured pin protrudes from the valve.

    None the less I tried these other "fixes"incase the proportioning valve needed to be reset.

    Driving backwards and jambing on the Brake.This produced regular braking after a few attempts,so we bled the system again.
    Striking the Brake pedal with a large hammer.

    So I think the next step is to change the master cylinder and proportioning valve.

  2. #12


    I solved the problem,it was a faulty Master Cylinder.

    I replaced the front calipers and pads,the rear brake shoes,bled the system several times,investigated the proportioning valve.Finally I replaced the Master Cylinder and there the problem lay.

    Many thanks for those who have helped me.

    Good evening from Norway.

  3. #13
    Sr. Engineer
    Join Date
    Oct 2010
    Indianapolis, In


    So what lead you to the master cylinder?
    2000 GMC YUKON SLT, 5.3L tow pkg, G80 rear/w 3.73 gear

  4. #14


    There was really nothing left to replace.In hindsight when I bled the rear brakes,there was not the flow coming out that there should have been.I think buying a pressure gauge that you can attach the suspected faulty master cylinder would be worth while.

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