Problem bleeding Shimano BR-M575 Brakes

LazyD
LazyD Posts: 21
edited December 2014 in MTB workshop & tech
Hi,

Brakes on my bike are completely messed up the levels completely lost pressure because I bought it to a bike shop and they tried to fix it but couldn't and made it all a lot worse. A second bike shop also said they couldn't fix it. I have a full bleed kit but I'm having an issue when I attempt to follow the bleed procedure. I am following this video on youtube:
https://www.youtube.com/watch?v=o2c6ezHY0A4
The problem I am having is that when I get to the part when I start to push new mineral from the syringe into the bleed nipple and should expect to see it start to come up into the reservoir, it doesn't work like how it shows it on the video. In the video they get a substantial amount of mineral come up into the reservoir which they can then use to bleed the air out of the system. In my case I get a tiny bit of mineral come up into the reservoir and then the pressure gets so high that there is no way to keep the tube and syringe connected to the bleed nipple and no matter how hard I try it always bursts off and I can get no more mineral in. As you can see in the video they do not seem to have that problem, they are able to push oil into the system with relative ease.

I'm hoping someone here has seen this before and knows what could be causing this.
Thanks.

Comments

  • keef66
    keef66 Posts: 13,123
    Can't access the YouTube vid cos I'm at work. I know nothing about bike hydraulics but have worked on plenty of cars.

    Your description sounds like you're trying to force fluid into a sealed system, and you only get a tiny bit in because you're compressing the air in the system.

    Sounds like a bleed nipple needs to be opened somewhere to allow air / old fluid out as you to push the new fluid in.

    http://si.shimano.com/#

    Shimano Dealer manuals. The very top one General Operations DM-GN0001-08, go to page 70.

    Quite detailed step by step instructions for replacing the hydraulic fluid and bleeding the system from scratch. Looks like you need a Shimano bleed funnel to attach to the lever once you've taken out the bleed screw, and then the hose / syringe at the bleed nipple on the caliper.

    They make it sound like a proper faff getting all the air out though!
  • The Rookie
    The Rookie Posts: 27,812
    If the reach adjust is wound right out it can inhibit fluid flowing back into the reservoir from the M/C, try easing it off a bit.
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.
  • cooldad
    cooldad Posts: 32,599
    Sounds like the reach adjust as Rookie said.

    They are normally really easy.

    Next time get an Epic kit without the silly funnel, but their how to is pretty straight forward.

    http://www.epicbleedsolutions.com/blog/ ... no-brakes/
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  • LazyD
    LazyD Posts: 21
    It did seem to be wound very far out so I put it in some, it did make a difference, it would then allow more liquid through but still not enough and it would still burst off at some point. In the end I took it to a good bike mechanic that was recommended to me and he has sorted it. Thanks for your replies.

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