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brake bleeding

Discussion in 'The Garage' started by erin3183, Feb 16, 2004.

  1. erin3183

    erin3183 Registered Member

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    I have an '89 chevy 4x4 that has a leaking master cylinder. I have a repacement that I am planning to bench bleed and install. At the same time I want to flush my brake system by opening all of the bleeder valves to gravity bleed while keeping the reservoir filled with new fluid. I have read quite a few articles but haven't got a clear answer on whether or not doing this is a sufficient way of getting the all of the air out? Will the air trapped from the MC swap be removed by gravity bleeding? Any help would be greatly appreciated.
     
  2. Blue85

    Blue85 Troll Premium Member

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    I don't even know if gravity bleeding is possible. Have the lines coming from the M/C open for as little time as possible and if you can, have something ready to plug them while you change the M/C. The less air you get in them the less there is to bleed out. To flush the fluid, why not just do it the old fashioned way by opening the bleeders one at a time an pumping the pedal?
     
  3. erin3183

    erin3183 Registered Member

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    I actually had no intention of flushing the entire brake system until I began searching for the best way to swap out MC's. Thats when I found out that the fluid degrades and absorbs water over time and should be flushed as often as every 30k miles to remove contaminants, prevent brake parts corrosion and maintain performance. I figured now is the time to do it since I have to bleed the system anyway and to my knowledge this truck has never had a flush in it's 140,000 mile life. I'd never heard of this before, but just about every article I read said "gravity bleeding" was the best way. Open all 4 bleaders and let the fluid run out them, close each as you see the "new" fluid come out, making sure to keep the MC filled at all times with new fluid. I just want to be sure that I get the correct end result.
     
  4. Beast388

    Beast388 1/2 ton status

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    When I swaped my in 3/4 ton axles, I had to bleed the rear brakes. I used the gravity bleed method. I just opened up the rears one at a time and let them bleed until the fluid was clean and bubble free. Of course I kept the MC fluid level up like you described and it worked quite well.

    I will most likely gravity bleed the fronts once I put the extended lines in. /forums/images/graemlins/waytogo.gif
     
  5. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    Gravity bleeding is indeed possible. That's the process I've used everytime, and it works like a breeze. I'm sure there are better ways of bleeding if you have a lot of air in the lines, however.
     
  6. erin3183

    erin3183 Registered Member

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    Cool, thanks for the feedback
     
  7. gravdigr

    gravdigr 1/2 ton status

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    I use one of those mityvac hand vacuum pumps. It works well. You hook it to your bleeder and it sucks the fluid through the system and into a resevior. Advantages are 1 man job, no mess, faster than gravity bleeding if you are in a hurry.
     
  8. lukebaby1

    lukebaby1 1/2 ton status

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    /forums/images/graemlins/peace.gif /forums/images/graemlins/peace.gif /forums/images/graemlins/woot.gif /forums/images/graemlins/woot.gif Here you go www.phxsyss.com
     
  9. Triaged

    Triaged 1/2 ton status

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    I have found gravity bleeding to work the best when there is no fluid in the lines. Be warned it takes a while to do it the gravity way. When I did my axle swap it took about 30min to get fluid to the rear brakes.
     
  10. landcrusher

    landcrusher Registered Member

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    [ QUOTE ]
    I use one of those mityvac hand vacuum pumps. It works well. You hook it to your bleeder and it sucks the fluid through the system and into a resevior. Advantages are 1 man job, no mess, faster than gravity bleeding if you are in a hurry.

    [/ QUOTE ]

    I use a vac bleeder also. Big plus for one man operation. The only drawback I have experienced is that air is sucked past the bleeder threads. Sometimes it's hard to determine if air is from the line or from the threads.
     
  11. gravdigr

    gravdigr 1/2 ton status

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    [ QUOTE ]
    [ QUOTE ]
    I use one of those mityvac hand vacuum pumps. It works well. You hook it to your bleeder and it sucks the fluid through the system and into a resevior. Advantages are 1 man job, no mess, faster than gravity bleeding if you are in a hurry.

    [/ QUOTE ]



    I use a vac bleeder also. Big plus for one man operation. The only drawback I have experienced is that air is sucked past the bleeder threads. Sometimes it's hard to determine if air is from the line or from the threads.

    [/ QUOTE ]

    rub some petroleum jelly around the bleeder when you open it. Fixes that problem...also seems to keep the bleeder from seizing to the caliper.
     
  12. landcrusher

    landcrusher Registered Member

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    [ QUOTE ]

    rub some petroleum jelly around the bleeder when you open it. Fixes that problem...also seems to keep the bleeder from seizing to the caliper.


    [/ QUOTE ]

    Good tip. I'll have to try that next time.
     

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