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Technical Bleeding brakes

Discussion in 'The Hokey Ass Message Board' started by upspirate, Oct 5, 2019.

  1. upspirate
    Joined: Apr 15, 2012
    Posts: 2,198


    I was bleeding some brakes today using a my-ti-vac.
    When I cracked the bleeder screws and tried to pull a vacuum, the needle moved then just fell off to 0.
    If I closed the screws, it would pull vacuum just fine so I think it was leaking at the threads.
    I cracked open the screws and pumped the master till I saw fluid coming out the tubing into the canister,and then tried to pull a vacuum,but never got pure fluid.It was like leaking at the threads.
    I'm going to go back and re-bleed with someone to help,but wondered if anyone had a fix for the vacuum way?
  2. lostone
    Joined: Oct 13, 2013
    Posts: 1,301

    from kansas

    I've had that problem too. Sometimes I was able to open about 1/4 total 1/2 turn and actually push in on the hose and bleeder. By holding the vacuum pump in 1 hand and with the other hand holding the hose and pushing in on the bleeder I was able to get the threads to somewhat seal and pull vacuum.

    Never found anything other solution to using the vacuum pump.
    brEad and upspirate like this.
  3. Yeah, leaking at the threads... teflon tape on the bleed screws helps. I finally gave up on the vacuum bleeder and went to Speed-Bleeders; they work great.
    upspirate likes this.
  4. upspirate
    Joined: Apr 15, 2012
    Posts: 2,198


    Thanks, though I was doing something wrong.
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  5. upspirate
    Joined: Apr 15, 2012
    Posts: 2,198


    I'll have to try that
  6. upspirate
    Joined: Apr 15, 2012
    Posts: 2,198


    I had read on a different forum someone said to use teflon paste on the threads, but I wasn't sure that would be a good idea if they got sucked into the "brake part" (trying to keep HAMB friendly;))
  7. blowby
    Joined: Dec 27, 2012
    Posts: 6,744

    from Nicasio Ca

    Had to redo a leaky fitting the other day, at the MC. When I was done, the brakes were spongy and pedal low. I drove it around hoping the air would escape on it's own. Didn't. A friend stopped by so he hopped in and I cracked the line loose. Didn't get the usual sputtering of brake fluid and air, all I saw was fluid dribbling out. But that one attempt fixed it, high hard pedal now. Got me wondering just how much air it takes in a system to impair it. Not much I'm thinkin'.
  8. 54vicky
    Joined: Dec 13, 2011
    Posts: 1,432


    there will not be enough vacuum (in fact none) on bleeder to pull in.all you are doing is filling the gap between the threads.I have not needed to do it with my mitivac but it makes sense.just do not get ham fisted and over do the tape
    VANDENPLAS likes this.
  9. bobscogin
    Joined: Feb 8, 2007
    Posts: 1,745


    Speed Bleeders are nice. They have a plastic coating on the threads that seals them. I found that you can vacuum bleed with them as well. The Mighty-Vac pump easily lifts the check ball, and the sealant keeps the threads from passing air.

    alchemy likes this.
  10. MAD MIKE
    Joined: Aug 1, 2009
    Posts: 543

    from 94577

    Not much at all. Air compresses, fluid does not.
    It works fine once or twice but that sealant tends to harden and then crumble off.
    Don't mess with speed bleeders anymore, have had them fail too many times just not worth the hassle.
    I prefer to have an extra set of regular bleeders ready with yellow gas Teflon tape(not the white liquid Teflon tape). Don't need them to seat, just seal the threads. Unscrew the existing ones and spin in the dedicated bleeder screws. Who wants to mess with blocked up bleeders.

    If you are going to vacuum bleed brakes, don't pull more than 15inHg. Beyond that you are gonna start sucking air in through the wheel cylinder seal.
    HemiDeuce and cktasto like this.

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