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so how do you tell when a proportioning valve goes bad?

Discussion in 'The Garage' started by milspecjimmy, Mar 16, 2003.

  1. milspecjimmy

    milspecjimmy 1/2 ton status

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    over a week ago i had a brake light come on, and lost the pedal. so today i changed the master out for a new one(not a reman). no dice, still have the light and still have no rear brakes. i have the 13x3" shoes in the rear on a 14Bsf axel. and it worked fine when i put it on. i have no wet spots on the frame, and no obvious leaks. calipers in front are dry, rear backing plates are dry, no fluid seaping out of the drums, and it has been sitting for over a week since the problem occured. i am going to go out and see how far out of adjustment the rear shoes are, and if that helps. i just want to get people thinking about it so i can figure it out when it turns out not to be the rear shoes(enter murphy's law). so if a prop. valve does go bad, what does it do and how do i tell. and is there any way to check the vaccume booster?
     
  2. oatsk5

    oatsk5 1/2 ton status Premium Member GMOTM Winner

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    Ok i mabe wrong but if i remember right the prop valve has a plunger type set up the plunger has divits in it that work together with an electric switch if the prop valve gos to far either way it triggers the brake light now i dont remeber if and or how it can be reset im thinking if you have to floor the brakes but cant remeber il go look at mine since it right there (no front clip) /forums/images/graemlins/thumb.gif
     
  3. MudNurI

    MudNurI 1/2 ton status

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    ahhhhhhhh BRAKES S*CK!

    My light came on- when I lost my rear brakes- due to a break just beyong the muffler on the main rear line.

    My "flap" on th combo valve (prop valve) had flipped to the wrong side- and no matter what I did, I couldnt get them to bleed....OR get the light to go out. After listening to different idea's on here, we ended up loosening up the lines on the valve...first just the front...banged it a bit with the ratchet in hand, then did the back- banged it again......Jumped in the truck....started to bleed the brakes- took 2 "bleeds" to get the dash light to go out....the second time I held it to the floor, and released the bleeder- the light went out....

    havent seen it since...and I've been driving it every day for the last week.

    Brandy
     
  4. supersize75

    supersize75 1/2 ton status

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    uh when it doesn't "proportion" any more /forums/images/graemlins/rotfl.gif

    j/k I know crap about breaks, I have every thing to do my disk brek swap from atron but I ain't looking forward to it /forums/images/graemlins/thumb.gif
     
  5. hardcore_rob

    hardcore_rob 1/2 ton status

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    I had to replace my proportioning valve withing the last 2 months. it kept leaking all my fluid out of it. there was leak. slow at first then going through the process of having to refill my reservoir before driving anywhere and repeating the process constantly. might wanna check the nuts that connect the brake lines to the valve directly at first. they might be leaking your fluid out. if not. could be a pinhole type leak. i went to a boneyard and picked one up for 20 bucks and worked just fine. just make sure you bleed your brakes properly if you replace the part. ** and this information comes from a 1981 time frame prop valve. i assume they havent changed that much.**
     
  6. milspecjimmy

    milspecjimmy 1/2 ton status

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    ok heres the skinny, i had a pin hole in a new rear line (new like a few months when i put the axel in) and the reason i didnt see any leaks was that the prop valve stuck and wouldnt let any fluid into the rear line. i fixxed the line, and tried to bleed it, no dice. hard pedal, and no fluid comming out thee bleeder. i then loosened the bleeder on the drivers side front, had my dad push the brake pedal, and had him hold it to the floor to relieve the pressure on the lines, then wacked the $hit out of the prop valve, tightened the bleeder and had him let off the pedal. then the bleeding process went fine till i go to the passenger side front. turns out that there is a hole in the outside of the bleeder screw where it is supposed to be, but it didnt come out any where on the inside, where it is also supposd to have one so the fluid can go through it. /forums/images/graemlins/angryfire.gif i hate napa /forums/images/graemlins/angryfire.gif so tomorrow ill hit the parts store and then bleed the front circut. all is well and the pedal is high but a little spongy, but not too much. thanks for all the help guys.
     

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