Diagnosing leaking calipers?

bobbydigital
bobbydigital Posts: 254
in MTB workshop & tech
Is there any real way to determine if a caliper is leaking?

Sometimes I see tiny bubbles or fluid when pressing the brake lever but if I hold the lever down, it stays solid, I would expect if the seals in the caliper were leaking that it would cause the lever to eventually to the handle bar?

Comments

  • david37
    david37 Posts: 1,313
    bobbydigital said:

    Is there any real way to determine if a caliper is leaking?

    Sometimes I see tiny bubbles or fluid when pressing the brake lever but if I hold the lever down, it stays solid, I would expect if the seals in the caliper were leaking that it would cause the lever to eventually to the handle bar?

    look for black muck sticking around the inside of the caliper, in lines on the disc. Remove the pads look for an oily imprint of the piston on the pads. If theyre Shimano, get them warranted or replace yourself. The cost is minimal compared to a couple of ruined pads and the general lingering pain in the arse.


  • reaperactual
    reaperactual Posts: 1,185
    edited September 2020
    Your lever travel will increase noticeably with a leak once the fluid in the brake reservoir has gone and air begins to enter the system.

    When I'm looking for a caliper leak I replace pads with a bleed block or spacer etc. wrapped in a paper towel, wrap a paper towel on the outside with elastic bands and leave the brake lever tied back to the bars under pressure overnight and check for wet patches in the morning.
  • david37
    david37 Posts: 1,313
    reaperactual said:

    Your lever travel will increase noticeably with a leak once the fluid in the brake reservoir has gone and air begins to enter the system.

    When I'm looking for a caliper leak I replace pads with a bleed block or spacer etc. wrapped in a paper towel, wrap a paper towel on the outside with elastic bands and leave the brake lever tied back to the bars under pressure overnight and check for wet patches in the morning.

    Finding wetpatches in the morning is never a good thing
  • reaperactual
    reaperactual Posts: 1,185
    edited September 2020
    david37 said:

    reaperactual said:

    Your lever travel will increase noticeably with a leak once the fluid in the brake reservoir has gone and air begins to enter the system.

    When I'm looking for a caliper leak I replace pads with a bleed block or spacer etc. wrapped in a paper towel, wrap a paper towel on the outside with elastic bands and leave the brake lever tied back to the bars under pressure overnight and check for wet patches in the morning.

    Finding wetpatches in the morning is never a good thing
    Lol! Nice one david37 🤣👍 I put it down to my parts getting old!
  • bobbydigital
    bobbydigital Posts: 254
    Thanks for the replies.

    I just find it hard to remove fluid from the face of the pistons.
    Sometimes I use their own fluid as lube after I have cleaned the pistons off with alcohol and then it's really difficult to determine if it's fluid leaking or just old stuff I used to lube.

    Now I just use hunter lube the hope stuff, at least it's not runny so hopefully won't leave any residue that could be confused as fluid leaking.


    I have some V2 and they were showing signs of caliper leaks, bubbles and fluid around the pistons but in the end they bled up solid and have been fine since.

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