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Projects Brake bleed air

Discussion in 'The Hokey Ass Message Board' started by iwanaflattie, May 6, 2019.

  1. Hi.
    Me again..
    Im having trouble bleeding the brakes on the COE.

    Ive succesfully bled brakes before but this time is fightimg back at me a bit.

    Dont want to be specific about donor vehicle cuz thread will be shut down.

    I have no leaks,new rubber lines,new steel lines except one big line to the rear..no leaks new MC,no leaky cylinders but still have bubbles in line...
    Any ideas?
     
  2. Did you bench bleed the master cyl? Do you have any pedal at all?
     
  3. trollst
    Joined: Jan 27, 2012
    Posts: 2,108

    trollst
    Member

    If the master is the hanging pedal type, mounted o the firewall, just open the bleeder screw on the axle and wait patiently. Do one at a time, be patient. Gravity is your friend.
     
    RMR&C likes this.
  4. I do have pedal,but cant get the small bubbles to stop coming like its getting air out of the wheel cyl.
    I did not bench bleed it.

    Maybe im not patient enough..
     
    Sandgroper likes this.

  5. How old is your brake fluid? Maybe moisture bubbles.
    It takes a while to get all of the air out of a new system. I'd drive it a bit at low speeds and see how the brakes feel. Any air should accumulate at the wheels and come out as a burst when you bleed.
     
  6. The system was empty,this is first time with fluid in yearss,im hoping that im tryng to speed the process and im getting a bit desperate
     
    Last edited: May 6, 2019
  7. Doublepumper
    Joined: Jun 26, 2016
    Posts: 1,534

    Doublepumper
    Member
    from WA-OR, USA

    If you didn't bench bleed the MC there will be lots of air to bleed out of the system. It will take some time to get it all out. You'll just need to keep bleeding it until all the air is removed.
     
    Special Ed and INVISIBLEKID like this.
  8. 41rodderz
    Joined: Sep 27, 2010
    Posts: 6,540

    41rodderz
    Member
    from Oregon

    Agreed. Always best and easier to bleed M/C on the bench before installing.
     
    Special Ed and INVISIBLEKID like this.
  9. Good to hear,i'll keep pumpin her
     
    BJR likes this.
  10. mark latham
    Joined: Oct 24, 2018
    Posts: 105

    mark latham
    Member

    I know you probably already know this but it has to be asked, do you have disc brakes and if so are they mounted with the bleeders at the top?
     
  11. Yes disc brakes and the bleeders are a the top...
    Seems like no air bubbles in the front lines but air bubbles in the rear...
    It seems like its getting better
     
  12. I find it can take up to 100 pumps to get the air out.

    @iwanaflattie ,,, the master cylinder needs to be bled by itself. If not the master cylinder will continue injecting air into the lines and you get to keep chase it all the way thru to the bleeders. Also if you do happen to let the MC barrel run dry while bleeding and pumping then you just lost your bench bleed and have to start over.

    They call it “bench bleeding” but it doesn’t need to be done on the bench. It’s just bleeding the master alone and getting all the air out of it. At the very end you’ll see tiny tiny tiny almost microscopic bubbles. When that happens your almost done.
     
  13. thanks I will give that a shot,I remembered to not let the MC get empty,will report soon
     
  14. Petejoe
    Joined: Nov 27, 2002
    Posts: 12,263

    Petejoe
    Member
    from Zoar, Ohio

    Same subject.
    I’ve bled a a “single pot” master cylinder by the provided directions.
    These directions provide a plug for the port and it tells you to pump the plunger until bubbles stop forming in the bowl.

    On the other hand I’ve had guys tell me that’s not correct and a line should be place at the port and run directly into the bowl.
    What is everyone’s opinion on this?
     
  15. earlymopar
    Joined: Feb 26, 2007
    Posts: 1,608

    earlymopar
    Member

    The easiest way of removing air at the M/C is similar to releasing air at the calipers or, wheel cylinders on a drum system. Pump to build pressure, hold and then wile holding, loosen the line fitting at the M/C. Tighten and check pedal height. Usually it only takes a couple of cycles like this to remove any remaining air.
    - EM
     
  16. Happydaze
    Joined: Aug 21, 2009
    Posts: 1,903

    Happydaze
    ALLIANCE MEMBER

    When 'bench bleeding', whether on the bench or on the car, the master cylinder must point downwards slightly (from the pedal input end) otherwise trapped air will never get out completely. If doing it on the car you might need to raise the front, or rear to achieve this orientation of the master.

    Chris
     
  17. slayer likes this.
  18. Sure would be great if all master cylinders had bleeders
    B310DDBC-0BDE-49CE-BD57-38FC23B23C7B.jpeg
    5D4BFE92-688C-4A75-852E-4F35E674A029.jpeg
     
    saltflats likes this.
  19. saltflats
    Joined: Aug 14, 2007
    Posts: 12,592

    saltflats
    Member
    from Missouri

    Adjust the rear brakes up tight, then bleed them.
     
    Chucky and 31Vicky with a hemi like this.
  20. drptop70ss
    Joined: May 31, 2010
    Posts: 1,201

    drptop70ss
    Member
    from NY

    I have also had small bubbles show up from the bleeder screw being too lose and air coming in around the threads. I now loosen the bleeders only enough to let the fluid out.
     
  21. Thanks all great info
     
  22. TrailerTrashToo
    Joined: Jun 20, 2018
    Posts: 1,289

    TrailerTrashToo
    Member

    Just the opposite experience on my last 3 vacuum bleed sessions. The vacuum was pulling air past the bleeder screw threads. Thought about teflon on the bleeder screws, but went back to the pump the pedal method.
     
  23. Idk fellas,,
    I’ve not ever had any troubles bleeding brakes unless there’s been a faulty component and when that was changed no problems. However I’ve also almost always had 2 people.
    How do I know there’s a faulty component someplace you ask,,, well when I have problems bleeding that’s how. Lots of times new parts are bad out of the box too. I find the faulty component thru isolation, logical process.

    Hydraulic Clutches sometimes give me something to bitch about.

    Some obscure faulty components can be wheel cylinders sucks air, lines and fittings yet pressure in a new system suck air, internal hose damaged, cracked brass, shuttle valve, residual valves, master cylinder that bypasses internally, haphazard lines that have up and over Air traps.
     
  24. So my combination valve pressure differential valve was moved out of center and was not letting full pressured fluid to the rear,,rebuilt it,now gotta find the bleeder tool locally
     
    31Vicky with a hemi and RMR&C like this.
  25. Some guys will argue about that shuttle valve being off center and blocking fluid till the cows come home.
     
    RICH B likes this.
  26. Rusty O'Toole
    Joined: Sep 17, 2006
    Posts: 9,657

    Rusty O'Toole
    Member

    The fluid can get mixed with tiny bubbles of air almost to a foam. Let it stand overnight and bleed it again. The air bubbles will rise to the highest point and form one big bubble. Once you get that out you are ok. This often happens when starting with a completely dry system. Best way to avoid this that I have found is to use a vacuum bleeder and of course, bench bleed the master.
     
  27. I have a friend that owns a good auto repair shop. I was bleeding brakes on my car and I volunteered him to work the pedal. Between me opening the bleeders, he was pumping the hell out of the pedal. I had to ask him to humor me and not do that. All that does is make more air bubbles that need to be chased out.
     
  28. BJR
    Joined: Mar 11, 2005
    Posts: 9,814

    BJR
    Member

    Your my hero!:p:D
     
    31Vicky with a hemi likes this.
  29. My pedal person gets instructions to go slow and pull the pedal all the way up with foot under pedal every stroke. It’s not a race
     
  30. speedshifter
    Joined: Mar 3, 2008
    Posts: 312

    speedshifter
    Member

    A simple pressure bleeder that works. Drill & thread a1/4" pipe thread in the lid of your mast cyl. Screw a air hose fitting in the hole. Bleed down shop air compressor to about 10lbs. Turn off power to the compressor. Connect air hose from the compressor to the mast cyl lid. (Fill mast cyl reservoir) Open bleeders one at a time& you are done. Greg
     
    jebbesen likes this.

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