Master cylinder bleed nipple threads wet

Discussion in 'Tech' started by svracer22, Jul 2, 2019.

  1. Britt

    Britt Well-Known Member

    Then please explain why it is there...since the bleeder seals on the taper and seat..
    Last edited: Jul 5, 2019
  2. beathiswon

    beathiswon Well-Known Member

    That is a "Speed bleeder" in the photo. They put sealant on the threads so that it doesn't suck in air if you use the pump-the-lever method to bleed your brakes. Most people use a constant vacuum or a pressure bleeder when using regular bleed screws and sealant is not needed to prevent air from returning into the system. Some have used sealants or Teflon tape successfully to seal just the threads for bleeding but I've seen a few times where the sealant got sucked into the system causing blocked passages..... not good.
    Britt likes this.
  3. Spitz

    Spitz Well-Known Member

    The bleeder you pictured looks like a speed bleeder to me. The bottom of the bleeder (tapered seat) is what does the sealing, nothing to do with any threads, unless stated above, you need to pull a vacuum on it or it's a speed bleeder (which will need the threads sealed (from air leakage!) to operate it properly and draw the more viscous brake fluid into the the master when you release the lever, other wise you're just going to pull air back into the caliper.

    pscook and Britt like this.
  4. blue03R6

    blue03R6 Well-Known Member

    The ones for cars (not speed bleeders) Also have thread sealant. I'm not suggesting not to investigate and replace but as a extra insurance.
    I suggest you look harder at the above picture. It even mentions a patented thread sealing system:crackup:
  5. Britt

    Britt Well-Known Member

    You're not real bright mechanically are you?

    Again...and S l o w l y.... It doesn't Seal Brake Pressure on the FuckingThreads...

    Depending on sealer, on a brake bleeder that May have a damaged seat is a Bad Idea.. and may cause bodily harm.
    Last edited: Jul 6, 2019
  6. Spitz

    Spitz Well-Known Member

    Don't know of any brake system that relies on thread seal to make a seal, everything is flared, just like the bleeder tip, only exception is banjo connections. I don't get the confusion? Never seen a car brake have sealers on the threads. If there is on some exotic shit, its probably to keep shit OUT of the threads, not keep brake fluid in. But, i haven't seen it on any of the american junk we work on in the last 20 years.
  7. Britt

    Britt Well-Known Member

    It is there to aid in bleeding the system.
    Back when we had stone and wooden wheels we used grease on the threads to prevent air from messing with the bleeding process.
  8. stangmx13

    stangmx13 Well-Known Member

    a mityvac works so much better when i do that
  9. svracer22

    svracer22 Well-Known Member

    So I cleaned the top of the threads well and let it sit. No fluid. Then I used a zip tie to hold the lever overnight. Tiny amount fluid around threads. This tells me the seat isn't sealing properly. It's as tight as I'm willing to tighten it.
    So Triumph doesnt list just the bleed screw separately. Looks like I can buy these just about anywhere. The stock one is aluminum. Do i need to replace it with an aluminum one or would steel, stainless steel work? Is there a company that makes quality parts. Last thing I want to do is replace this with Chinese junk.
  10. gapman789

    gapman789 Well-Known Member

    Just buy a new Brembo, Accossato MC or the like and be done with it.
  11. Spitz

    Spitz Well-Known Member

    Whats the body made of?
  12. IrocRob

    IrocRob Well-Known Member

    Steel is fine, just be certain to get the correct thread size for that master cylinder.
  13. svracer22

    svracer22 Well-Known Member

    Master cylinder body is aluminum.
  14. Spitz

    Spitz Well-Known Member

    My only concern would be galvanic corrosion at that point, but it should work if you can't find a suitable aluminum one. Are you 100% the bleeder is aluminum or is it just not ferrous?
  15. svracer22

    svracer22 Well-Known Member

    It's aluminum
  16. Britt

    Britt Well-Known Member

    Personally, I'd swap them out for Steel/Stainless and never give it another thought.
    (Not a fan of alum bleeders or bolts).
  17. svracer22

    svracer22 Well-Known Member

    Thanks. I will try that.
  18. pscook

    pscook Well-Known Member

    If the fluid is able to work its way past the sealing surfaces and wick along the threads, how much fluid is coming out of the bleed hole? It seems to me that fluid always finds the path of least resistance, so why would the fluid choose to work through the threads instead of just leaking out of the big open bleed hole at the end of the bleed nipple?
  19. badmoon692008

    badmoon692008 Well-Known Member

    I suggest you look harder at the above picture. Did you read what they specifically say the patented thread sealing system is sealing out? Based on your input here and in some other threads I haven't decided yet if you're a troll or just stupid.
    Britt likes this.
  20. Spitz

    Spitz Well-Known Member

    You'd think. Maybe just residual fluid hanging around. If the port to the outside is full of fluid it will eventually try to level itself out and leak around the threads to do so. I always just blow mine out with compressed air really well, then I know if anything comes back it's a leak.
    Britt likes this.

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