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This brake is refusing to bleed

Discussion in 'XJ Technical Chat' started by MadMaxMidnight, Nov 6, 2017.

  1. MadMaxMidnight

    MadMaxMidnight New Member

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    Hello everyone, the front brake on my 82 XJ650 Midnight just will not bleed. It's a fresh system with rebuilt MC (assembled according to write-ups on this site), new galfer braided lines, and pads. I also put a fresh bleeder screw in the caliper. No matter which bleeding method I've tried, it will not build pressure on the lever. I've tried the turkey baster/syringe, Mityvac, and old school ways, all to no avail. Am I missing something? I've lurked on this site for a while, there's some outstanding knowledge in here. Shout out to Len as well, for always having just the right part. Thanks in advance!
     
  2. Timbox

    Timbox Active Member

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    Welcome to the forum,

    Sounds like you have been reading and doing all the right things so far, good to see you doing your homework.

    You are able to move fluid out of the farthest from the MC bleeder screw with lever? If so then it is just time. I would get a rubber band or a clamp of some type and clamp the brake lever pulled in all the way to the bar over night. Then see if that helps, it has for me on more then one bike.
     
  3. jayrodoh

    jayrodoh YimYam Premium Member

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    Remove the line from the MC and try pumping the lever. You really can't screw up the caliper rebuild, I'm thinking something is wrong with your MC. You should be able to get fluid to squirt easily from the MC when you pump the lever. Brake fluid is nasty and can remove paint so do it off the bike. Is it the stock MC and handlebars? Some bikes have swapped out bars and the MC will sit at a weird angle and not work as well.
     
  4. MadMaxMidnight

    MadMaxMidnight New Member

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    It will push a very small amount of air at the bleeder for the first three or four cracks, but then seems to pull vacuum on the next crack. It squirts from the reservoir easily when pumping the lever, but it doesn't seem to push down the line. I tried it off the bike, and was getting very little, just beads of fluid. I skipped a caliper rebuild (was trying to rush to make the rally), but it was working before and it doesn't leak now. Could that affect it this way? I'll go strap the lever down as well, I haven't tried that. Thanks!
     
  5. XJ550H

    XJ550H Well-Known Member Premium Member

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    it is a single disc correct? you should rebuild your caliper. try wrapping some teflon tape around the bleeder screw you could be sucking air down the threads.
    also make sure the brakeline union is clear of any debris
     
    Last edited: Nov 6, 2017
  6. XJ550H

    XJ550H Well-Known Member Premium Member

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    did you clean out the tiny hole in the mc resevoir
     
  7. MadMaxMidnight

    MadMaxMidnight New Member

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    It's a single disk, correct. I did clean out both holes in the MC, and flushed everything with brake cleaner and compressed air before reassembly, and did the same with the union. I thought maybe the MC bore was pitted or damaged, but I couldn't see anything obvious both times it was apart. I tried teflon tape on the factory bleeder, then ditched that for a new one. I've got a caliper rebuild kit on the way, too
     
  8. jayrodoh

    jayrodoh YimYam Premium Member

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    It is possible to put the seal in backwards on that MC. Have a pic of how you assembled the plunger and seals?

    Here's a good video on that MC.

     
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  9. MadMaxMidnight

    MadMaxMidnight New Member

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    No pics, but the seal is oriented so the larger flared end is facing into the bore. I noticed the piston in the video requires two seals; mine only had the one. I've included an internet pic of the kit I used. The seal is installed just the way it is in that pic
     

    Attached Files:

  10. jayrodoh

    jayrodoh YimYam Premium Member

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    That's correct. There has to be some type of seal on the end of the plunger, that is the one that passes the holes and creates pressure.
     
  11. MadMaxMidnight

    MadMaxMidnight New Member

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    I'm a bit confused now. The original plunger only had one seal on it, and the kit matched what I removed. All parts are accounted for, with a 1-for-1 replacement. I thought I may have had the spring oriented the wrong way, but when I tried it flipped, it only locked up the MC. Did I use the wrong kit possibly?
     
  12. jayrodoh

    jayrodoh YimYam Premium Member

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    Your picture looks like the right kit, you have that rubber disc on the spring between the plunger and spring right?
     
  13. jayrodoh

    jayrodoh YimYam Premium Member

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    Here is the breakdown, terrible pic though.

    Untitled.png
     
  14. MadMaxMidnight

    MadMaxMidnight New Member

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    Ahhh, that may be the culprit. I have the the spring flipped around so the disk is at the bottom of the bore. I thought that may be incorrect, but when I tried the way you describe, it locked up the plunger completely. I assumed I had it wrong
     
  15. jayrodoh

    jayrodoh YimYam Premium Member

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    Yes, that rubber disc is what pushes the fluid. Without it, all the fluid is pushing back up into the reservoir.
     
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  16. kosel

    kosel Active Member Premium Member

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    I find it easiest to check one small section of a system at a time. Here's how a friend and I tested just the MC:

    Leave the MC on the handlebars. Use an old, short brake line and seal the banjo on one end with a nut and bolt and two rubber washers to seal it up. Connect the other end to the MC. Fill the MC and then bleed the system. It's short and simple, so doesn't take long. Since there were two of us, one worked the lever and the other tightened the seal at the end of the line. Once bled, tighten things up and test the lever.

    I'm sure others here have even simpler means.
     
  17. MadMaxMidnight

    MadMaxMidnight New Member

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    When I get home from work, I'll flip the spring and disk back around and try again. Thank you all for your input, I'll let you know how it turns out
     
  18. nablats

    nablats New Member

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    i use a sealey vacuum bleeder it uses a hand pump to create a vacuum in a plastic jar. you just open the bleed screw and it sucks the fluid through. no sweat one person operation, just keep the mc topped up.....
     

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