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brake help asap

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by evil bastard, May 7, 2000.

  1. evil bastard

    evil bastard Registered Member

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    Location:
    central wa state(yaakima valley)
    replaced my 74s calipers and pads today, only to find that i had no pressure on the pedal. we bled the brakes, over and over and over(filled the front reservoir 4 times) and still can put the pedal to the floor easily. since my rear shoes are gone, i have no brakes. tomorrow im going to swap my old calipers back and see what it does. anyone know what this might be?
     
  2. Goose

    Goose 1/2 ton status

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    There is a bypass button on the proportioning valve that must be depressed when bleeding the front brakes. I don't remember exactly why, but it needs to be done. Hold the button down whenever you are pushing on the brake pedal.

    Mud is just thick water, or is it that water is just thin mud?
     
  3. Blazer79

    Blazer79 1/2 ton status

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    Hey Goose:

    Is that button in all Blazer models? I don't think mine has been pushed ever. What does it do?

    <font color=black>//////
    What the heck!...Drive it like gas is $0.50/gal!!!
    </font color=black>[​IMG]
     
  4. Goose

    Goose 1/2 ton status

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    According to my Chilton's manual: The combination valve contains a metering valve that restrictts flow to the front brakes until the rear brakes overocme the force of their retracting springs to prvent front brake lockup, a pressure differential warning switch which activates a warning light if either the front or rear hydraulic circuit is losing pressure, and a proportioning valve which limits hydraulic pressure to the rear barakes to prevent rear wheel lockup. The valve is on all '71 and later models w/disc brakes. (My manual covers '69-'82.) The metering valve pin needs to be held in a slight amount to allow fluid flow to the front brakes. It should be under a black rubber seal on one end of the combination valve.
    I had MIDAS do my last brake job. I didn't have anybody to help bleed them & I needed a new master cylinder. The point being that it took 3-4 trained? professionals over 1 1/2 hours to get my brakes bled out all the way. I wonder if they new about the metering valve pin. Anyway, they got it done and I haven't had a problem in over 3 years now.
    Mud is just thick water, or is it that water is just thin mud?
     
  5. Blazer79

    Blazer79 1/2 ton status

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    Thanks Goose. I'll keep that in mind and check it the next time I have my breaks fixed.

    <font color=black>//////
    What the heck!...Drive it like gas is $0.50/gal!!!
    </font color=black>[​IMG]
     
  6. Burt4x4

    Burt4x4 3/4 ton status

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    Hmmmm, I wondered what that was???
    So what we need to do is pump up the brakes and hold the pressure then push the valve button in?? Then proceed with the front bleeding??
    Does anyone know what the proper procidure is??
    Any more dteails on this would be GREAT!![​IMG]
    Thanks

    Rock ON![​IMG] 72 K5 [​IMG]
     
  7. chaka73

    chaka73 1/2 ton status

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    Well.... I replaced my front brakes about a week ago but I didn't know anything about a bypass button, so I didnt' push it, dont have any problems though the brakes are working fine so far and I have a 73, according to the manual 71 and up mine should have the button but I dont know where it is if anybody knows please let me know thanks.

    LOVE MY GREEN GIANT!!!
     
  8. Burt4x4

    Burt4x4 3/4 ton status

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    I have one, atleast I think its one! On the front of the PPValve there is a rubber cover that pulls right off and pops back on. I was looking at this the other day and said, Hmmm wonder what thats for?? It has a round looking 'button' on the front tip of the PPValve. From thease post I would guess it puts all pressure to the front lines when breks are pumped up and heald then pusshing in the button pushes the fluid pressure thru the front lines??????? Mabie/Mabie Not..I duno??[​IMG]

    Rock ON![​IMG] 72 K5 [​IMG]
     
  9. skeepwerkzaz

    skeepwerkzaz Registered Member

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    I usually fill the calipers with fluid before installing them, and when the are both bolted on and ready to be bled, I get a clean oil squirt can fill it w/ brake fluid, put a small (about1/8th in) hose over the nozzle, undo the bleeder, stick the hose on the bleeder, and bleed from the bottom up. It is alot easier to push air up then down! It works for me, and I've never used the "magic button".
    Just my input!
    SKP 88 K5
     
  10. Goose

    Goose 1/2 ton status

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    My manual shows a picture of a tool rigged up to hold the valve in. Appearently, the valve is held in for the whole procedure. And the valve or metering pin, whatever you want to call it, is on the brake proportioning valve. On some vehichiles this valve is close the the master cylinder, on others it is on the front frame rail by the steering box. Anyway, it will have two lines in from the master cylinder, two lines out to the front brakes, and one line out to the rear brakes, plus a electrical connection(for your brake warning light) and the metering valve pin covered by a small black rubber cap. For some reason my Haynes manual doesn't even mentin the metering valve pin. Anywho, I hope I was helpful. Oh yeah, Dr. Evil, er, I mean evil bastard, did you bench bleed the master cylinder?

    Mud is just thick water, or is it that water is just thin mud?
     

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