Master cylinder bleeders: How much air pressure?

Discussion in 'Axles + Brakes' started by BigBadJohn, Oct 12, 2019 at 11:08 PM.

  1. BigBadJohn

    BigBadJohn Newbie

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    How much air pressure should you apply to bleeders like this?

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  2. grampadirt

    grampadirt On MEDICARE Officially Old

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    I do mine about 15-17psi.
     
  3. Supercharged111

    Supercharged111 I'm Awesome

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    I do mine at 10psi. Instructions specify 20, but 10 seems to do the job.
     
  4. BigBadJohn

    BigBadJohn Newbie

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    So just hook them to a compressor with pressure regulator or do the bleeder units do something besides apply air pressure to the reservoir?
     
  5. grampadirt

    grampadirt On MEDICARE Officially Old

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    Pump the tank up to needed pressure and disconnect the air supply,when fluid stops coming out of the bleeder you're working on pump it up again.I suppose you could set your compressor at your desired pressure and leave it connected but that might be a chancy.Oh,you do have a pressure gauge on the new fluid resevoir,right?
     
  6. BigBadJohn

    BigBadJohn Newbie

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    I guess I could add an air pressure gauge right before the inlet of the bleeder cover. It wouldn’t be hard. I was thinking of doing a remote button connected to a 120v air solenoid. That way I could pressurize it only when I was loosening the bleeder screws while under the vehicle
     
  7. east302

    east302 I'm Awesome

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    Motive Products makes a bleeder for that master cylinder reservoir adapter using (essentially) a pump-up garden sprayer. I’ve seen where people make them from scratch. Check YouTube, but you could probably rig one together fairly easily and add a gauge to it.

    The hard part is probably going to be getting a good seal on the reservoir. 10-15 psi would probably get you by. GM’s spec is 20-25 for pressure bleeding.

    I’ve used one before and it makes flushing/bleeding so much easier. You don’t lose much pressure cracking the bleeders so there’s plenty of time before having to pump it up again.
     

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