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Deore hydraulic disc brake stuck in the open position

PepPep Posts: 501
edited February 2016 in MTB workshop & tech
The Piston of my Shimano Deore hydraulic brake got stuck in the open position.
Both front and rear.
I dismounted the caliper and tried to clean them with tissue and oil, did not help, then again with alcohol, did not help, Then I left it overnight immersed in oil. Still stuck, even by pressing it with a flat head screwdriver no way to move it.
I cannot even clean the side surface of the Piston because it's completely inside the drum.

Out of desperation I just bought a new hydraulic brake set (the whole set: caliper, cable, Level, should be already bled), 60euro.

I was even tempted to move to mechanical disc brake, apparently not as strong braking power but should be easier to service, just not sure I could have found any mechanical disc brake compatible with my present rotor, changing also the rotors seemed wasting too much cash.

Perhaps I should have bled it?

Any advice?



  • PepPep Posts: 501
    Just to add:
    if I press the lever I feel very little resistance, absolutely zero movement of the of the Pistons.
    Sounds like air leaked inside the cable, right?

    Disc sets about 8yr old, and 40-50k miles.
    Pistons got stuck a few times before but I always managed to clean them and make them working again. This problem has been reoccuring increasingly more often.
  • The RookieThe Rookie Posts: 27,747
    How were you going to push the piston out with no pressure? I suspect the callipers are fine and you need to fix root cause.

    It's a hose not a cable and it should be filled with mineral oil not air, so no, no air should leak out.

    Sounds like they need a bleed.

    No need to change the disc if going to mechanical callipers, not sure why you thought you would need to?
  • oxomanoxoman Posts: 8,195
    If not 100% youtube clips for help and ideas. Better than a Haynes manual.
    Too many bikes according to Mrs O.
  • PepPep Posts: 501
    I learn now I should have serviced the caliper regularly (never bothered). I do service the chain and the pads very regularly.

    Yes, YouTube is fantastic for learning bike repair. And ParkTool stuff, both videos and tools, are probably the best.
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