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Leaking bleed nipple?

Discussion in 'Technical and Troubleshooting Torque' started by Mr Luke, Nov 10, 2010.

  1. So I fitted some Hel lines to my bike over the weekend and had it out at the track on Monday. After each session there was a tiny tiny bit of brake fluid around the base of the right front bleed nipple. I'd wipe it off and it would be there again at the end of the session. The brakes felt ok, though toward the end of the day the lever maybe felt a little softer and as though it came back closer to the 'bar than at the start of the day and the day before. Though maybe this was in my imagination.

    Any ideas about this guys? I suspect I may have over-tightened the bleed nipple when closing it off. Is this likely to cause it to wear and leak? And if so, what's the fix. I'm guessing a new bleed nipple. Is this something that is easy to source and fit?

    Thanks in advance.
  2. [​IMG]

    lol.... sorry 8-[
  3. Hmmm I don't think any of us were expecting that .... ?

    So..... you like...stuff?
  4. well leaking nipples are a serious subject...

    love stuff ;)
  5. Possibly. They only need to be firmly done up, not swung on with all your might. Overtightening can result in surface galling1, which will probably lead to minor leaks.

    The first step is to remove the nipple and inspect. If there is galling, you may be able to clean it up and refit with no further leaks, or you may need to replace it. Some bleed nipples have a hard surface like anodising which is smooth and produces less friction, to avoid galling. Some are just plan metal. There are lots of different types of after market bleed nipples available (at least last time I looked).

    I don't know how you can fix it if you have done significant damage to the internal surface, but I usually just screw the nipple to a snug fit a few times to smooth out any imperfections. Usually the metal used is somewhat "self healing" and will reform to the mating shape. That has worked for me. The nipple is supposed to be the part that gets damaged in overtightening.

    See how you go.

    1. Galling: A condition whereby excessive friction between high spots results in localized welding with subsequent splitting and a further roughening of rubbing surfaces of one or both of two mating parts.
  6. I can think of ways to reface the seat in the caliper, but the effort required, or expense if you could find someone to farm it out to, would make a used replacement caliper an attractive option for almost anything non-unique.
    • Like Like x 1
  7. Possibly one of the most disturbing thread titles ever
  8. Oh oh. Let's meet in real life. My place or yours??

    Rod, thanks for that. I will try opening and closing it a few times and see if that helps. I didn't hang off the spanner (it's only a small one anyway) but I think I probably put a few more pounds than the 7.5nm as per the service manual (which I seemed to pass by the first time). Dumb with hindsight though, as I would think it's incredibly unlikely that the tiny bleed nipple will vibrate loose (I would think). I guess you could just about finger tighten it to 7.5nm.

    Ah well. You live and learn...
  9. that's kind of why i put that photo up. it's the first thing that came to mind lol