I made the mistake of pulling my brake leaver whilst the wheel was off, so the piston came out, and I lost quite a bit of oil.

I pushed the piston back in, and proceeded to follow the bleed procedure for these brakes but I am having problems.

When I loosen off this bolt, about 1/4 turn, and inject the oil, all the injected oil appears to flow out of the thread shown within the red circle in the picture attached.

enter image description here

I've also tried sucking oil out of the top with a syringe but it doesn't seem like the system is open.

Could the loss of fluid be causing some kind of air blockage?

Could I have pushed the piston in too far, as there is no oil behind it now.

Should I try and force oil from the top down?

I havn't got loads of oil to spare, so I don't know what to do.

Please advise on refilling entire system, and if this is same procedure.


  • Tektro bleed instructions are usually pretty bad; can you confirm you're using a bleed block, and that when you're injecting new oil you've first opened the bleed port at the lever and attached a collection bag or bottle there? Are you sure you're opening the correct lever? Have you tried opening the caliper bleed valve a little more? Usually it wants around 1/4 to 1/2 a turn open, but that's something I've seen vary a little bit on different brakes. Sep 11, 2018 at 17:04

1 Answer 1


If you watch the Tektro video you will see that some fluid leaks from the bottom bleed port threads as the new fluid is injected.

If all the fluid is leaking out, then that might indicate a blockage. You may just be getting more leakage than expected because you have to refill the entire system.

The fully retracted piston should not be blocking the system.

  • Managed to get it working just by pumping the fluid through.
    – reggie
    Sep 16, 2018 at 13:43
  • @reggie Glad to hear you got it sorted. Sep 16, 2018 at 13:51

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