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How do you know when your MC or Booster is going bad or has gone bad?

Discussion in 'The Garage' started by Emmettology 101, Aug 22, 2002.

  1. Emmettology 101

    Emmettology 101 3/4 ton status

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    My brakes work decent on the 86 but the pedal goes down pretty far before the brakes actually work and then it seems llike the rears grab first. I was wondering if the MC or booster is bad? I bleed the fronts about a dozen times per side after swapping calipers(someone put them on the wrong sides) and then I gravity bleed them for about 2-3 MC full. Then we also bleed them about 6 times per side after that.

    Any ideas?
     
  2. Sandman

    Sandman 3/4 ton status Author

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    I would think MC over the booster. The booster would affect your overall feeling but it would still stop.
     
  3. Emmettology 101

    Emmettology 101 3/4 ton status

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    It still stops, just takes a longer pedal throw to do it. /forums/images/icons/smile.gif

    I am goign to check for a possible kinked line to the front. I bled the poop out of the fronts, I thought they would be better by now.

    I hate working on brakes!
     
  4. uglychevyZZ4

    uglychevyZZ4 3/4 ton status

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    Bad Booster-- will produce a hard / rock hard pedal since it has lost vacume ( booster just assists in pushing the pedal down with vacume ) /forums/images/icons/wink.gif

    Other- sounds like you have a bad something.. WHY do you think it is the fronts? is it nose diving? thats the rears if so. adjust up the rears and check for leaky wheel cylinders. Poss prop valve also..
     
  5. Emmettology 101

    Emmettology 101 3/4 ton status

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    Well the pedal is easy to push, so it is not the booster then....

    The Blazer stops relatively uniform(no diving) but it takes alot of the pedal travel to get braking. And it doesn't matter if I pump the brakes, it stays the same.
    I was just guessing it was the rears since I am getting no diving and since it takes so much of the pedal to get braking pressure(doesn't it work as the front brake first and then farther into braking the rears grab?)

    All in all it doesn't stop too bad if I could get it to stop liek that at normal pedal travel.

    The brakes are all new(as of 2 years ago and the Blazer had less than 500 miles put on it since).. Nothing is leaking and there is still good pads... Everything in the brake system was changed excpet for the main lines going to the rear brakes, the lines from the MC to the prop, the MC and the booster.

    When I have someone pump the brakes and I am close to the MC, I can hear a gushing sound and can see fluid buble and move in the rear resivior of the MC(the front chamber, correct?)... I have never seen this on any other vehicle.
     
  6. Sandman

    Sandman 3/4 ton status Author

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    I had the same problem. I threw the 1/2 ton MC away and bought the 1 ton version. I think it was around $35. Stops on a dime now.
     
  7. Sandman

    Sandman 3/4 ton status Author

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    You should not see any bubbles at all. It might be that your MC itself might need to be bled.
     
  8. Emmettology 101

    Emmettology 101 3/4 ton status

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    But the brake system is all factory(except for braided lines). I am running the stock drums in the rear.

    I could see if I went to rear disks, but I haven't changed anythign.
     
  9. Emmettology 101

    Emmettology 101 3/4 ton status

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    Can you do it installed by removing the lines and installing some rubber lines into the MC or do I have to remove it completely?
     
  10. Sandman

    Sandman 3/4 ton status Author

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    That part about them not pumping up throws me. Maybe you can check the adjustment rod on the pedal or something.
     
  11. Emmettology 101

    Emmettology 101 3/4 ton status

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    Maybe it was my wording... The brakes work ok, but the pedal travels pretty far(almost ot the floor beofre they work). I have had vehicles in the past that maybe had some air in the lines or something and the first pump or two the wouldn't work but then would work after say 3-4 pumps.
    The way the brakes are now, they feel like they may be wokring right, but have too much pedal travel. And with a vehicle that has properly working brakes, if you pump the pedal they work the same. And with non-working correctly brakes, you need ot pump them up to get the to a normal pressure.

    Did I make it more clear or more confusing? /forums/images/icons/laugh.gif
     
  12. Sandman

    Sandman 3/4 ton status Author

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    So they work fine but the pedal travels a long way. Is this correct?
     
  13. Emmettology 101

    Emmettology 101 3/4 ton status

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    Yes, once it starts stopping, it stops decently...
     
  14. uglychevyZZ4

    uglychevyZZ4 3/4 ton status

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    the rears allways work / draw fluid first, this is normal, stops you from NOSE diving.

    no leaks at all? did you look inside rear cylinder boots?

    maybe master? hearing fluid rushing is normal. try bleeding this way, old farts will disagree, but there is a reason, and ill prove it.

    1-DONT PUMP IT UP!!!
    2-have someone open the line at the master, one wheel line at a time, and when they open it, say" down" and when the FLUID STOPS FLOWING, CLOSE IT, if there are no bubbles, and all fluid move on.
    3-have someone open the line the given wheel yer on, and when they open it, say" down" and when the FLUID STOPS FLOWING, CLOSE IT. ( sequence is rr,lr,rf,lf )
    4-repeat at each wheel..

    the purpose of NOT pumping it is when a air bubble is not contained within itself, and is mashed, it spreads from one end of the line-to the other, thus making it harder to remove. if you disagree, ask Donimator /forums/images/icons/wink.gif he was sold. if none of thewse work, YOU NEED A MASTER. and dont forget to bench bleed it first, if you need directions, email me. /forums/images/icons/wink.gif
     
  15. Emmettology 101

    Emmettology 101 3/4 ton status

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    So pretty much this is a gravity bleeding method?
     
  16. thatK30guy

    thatK30guy 1 ton status Premium Member

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    I had a K10 shorty once and was going down a steep hill and when I got to the bottom, the brakes went hard. /forums/images/icons/tongue.gif

    Turned out the booster went "kerplunk." /forums/images/icons/laugh.gif

    It would still stop, but I had to push harder on the pedal to do so. I changed the booster to a new one and the soft feel came back again. /forums/images/icons/wink.gif
     
  17. uglychevyZZ4

    uglychevyZZ4 3/4 ton status

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    no, gravity bleeding is when you just open the valve, and let it flow freely, .. you WILL have to push down, but only ONCE slowly til flow stops then close it, dont go down b4 the valve is open, hence: spreading the air.it requires 2 people.
     
  18. Emmettology 101

    Emmettology 101 3/4 ton status

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    Ah, I see now. I was thinking you crack the line at the MC and at the wheel.

    SOrry, it has been one of those days!
     
  19. 69K5

    69K5 1/2 ton status

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    what does it mean when you have to pump up your breaks before you crank the truck and then they are hard but still dont stop for crap. if i dont pump it up they will go almost to the floor before the brakes start working. i cant wait to switch to discs.

    thanks

    nathan
     
  20. uglychevyZZ4

    uglychevyZZ4 3/4 ton status

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    means you need to pull wheels and drums and start inspecting /forums/images/icons/laugh.gif
     

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