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  1. #1
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    Hayes mag brake bleed; won't take fluid

    Weird. Tried to bleed my Hayes mags and I can't get any fluid through the caliper bleeder. Squeeze, squeeze, squeeze, and nothing comes out of the m/c and no fluid is used. M/C bleeder screw was removed (checked that about 10 times!) So, I fire up the air compressor, break down the system trying to figure where the blockage is.
    1) brake bleeder itself flows air
    2) pull the caliper halves apart, air up the ports and each piston blows out
    3) pull the hose from caliper and m/c and air flows
    4) blow air through the m/c nipple and air flows out through the m/c bleed port

    The only thing I can think of is the bolt that secures the hose to the caliper has a fluid port drilled in it, so I marked the location of it, bolted it back on, and it does not line up with the hose fitting port. But,there is no evidence of any spacers or washers to change the alignment of the port. My guess is that the "well" inside the fitting is wide enough so that the port hole location on the bolt doesn't matter.

    This brake was a "gift" so I have no history on it.

    What am I missing here?

  2. #2
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    Likely one of two things- caliper bleeder or the master cylinder piston is stuck in the brake. Last bit is if it's an older generation Mag. Was the lever sticking? What size hex key do you need to adjust the lever reach?
    You are not what you own.

  3. #3
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    Juan, 2.5mm to adjust the lever reach. Looks like the piston moves about 1/2" before it bottoms out. Caliper bleeder flows ok. When i tried to bleed, I made sure that the lever/piston was full open. I was thinking about opening the m/c anyway just out of desperation, but not sure what that will accomplish if the lever/piston move freely. Thoughts?

  4. #4
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    Plenty! First thing- did you remove the caliper bleeder and see if you could push fluid through it alone?

    Mags 03 and earlier used the 2.5, and they also had a plastic piston. These things fatigued over time and could start locking up inside the cartridge, much like some of the Juicy brakes are doing today. If the lever isn't snapping back on its own, like you have to push it back out, that's the indicator of it occurring. Bonus symptom is there's a click when you push it out and pull the lever.

    Next up is a contamination issue. If the wrong fluid was used at some point, or parts lubed up with some penetrating oil or grease, the seals will swell up and block off the orifices in the brake. Air might be able to find a path around it, but fluid can hydrolock as it is being pushed through.

    Parts for these brakes aren't easy to come by, and not all generations of Mag's parts were compatible with each other, much less most all of them are out of production. In the end, it may be more effective, time and cost wise, to replace the entire brake.
    You are not what you own.

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