Bleeding old shimano m525 brakes

ps4customgamer
ps4customgamer Posts: 34
edited April 2019 in MTB workshop & tech
So I have an old pair of shimano m525 brakes and I think theyre really solid except the rear which needs bleeding and new pads. I've checked the instructions and they tell you to do a very old fashioned bleed with a tube and bag but I dont have a bleed block so trying to do this without isnt working all I'm doing is getting air into the system.
http://www.bike-manual.com/brands/trek/ ... 25_eng.pdf
I was hoping to use a syringe to replace the 14yo oil in the system but when I've tried the system seems to be blocked by the levers, with the levers disconnected oil will push through the calipers and brake line but is blocked by the levers.
Does anyome know if its possible to undo a bolt on the levers so oil can bleed through them unrestricted or are they just not compatible with the 5 minute refill method?
https://www.youtube.com/watch?v=DsqlEYJeLQU&t=10s

I dont believe for a second the shimano factory paid workers with a tube, bag and spanner to spend hours bleeding new shimano brakes so I'm clearly missing something.

Comments

  • JBA
    JBA Posts: 2,852
    You cannot bleed those brakes unless you remove the reservoir cap on the lever, otherwise you are pushing against a closed system.
    The instructions you linked to show what to do. You don’t need a bleed block if you leave the wheel in situ. Otherwise just put a suitable sized piece of wood or LEGO between the calliper pistons.
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  • ps4customgamer
    ps4customgamer Posts: 34
    JBA wrote:
    You cannot bleed those brakes unless you remove the reservoir cap on the lever, otherwise you are pushing against a closed system.
    The instructions you linked to show what to do. You don’t need a bleed block if you leave the wheel in situ. Otherwise just put a suitable sized piece of wood or LEGO between the calliper pistons.
    Yes the reservoir cap was removed and bleed nipple loosened, sorry was already a long post didn’t want to put too much in. I thought there might be a removable cap or grub screw I could loosen so I could flush with a syringe. Is it possible there is something blocked or?
    I tried in situ as you said but it just doesn’t move enough after about an hour no difference in fluid levels in my reservoir, my brake pads and discs are fresh.
  • whyamihere
    whyamihere Posts: 7,700
    If you want to quickly flush the old oil out, you can remove the hose from the lever, push new fluid through from the caliper with a syringe (obviously make sure that the hose is pointing at a suitable receptacle) and empty the lever. Then, when you reconnect the brake hose (which will be full at this point), close the bleed nipple at the caliper, fill the reservoir with fluid and pump the lever while giving it a few taps to get any trapped air to escape. Then, if it still feels a bit spongy, follow the usual bleed instructions.
  • The Rookie
    The Rookie Posts: 27,812
    If the free travel adjust has been wound in too far it blocks the return flow path, you need to wind it back out.

    Had this on some old LX brakes (M665) I bought on a bike.
    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.

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