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When bleeding, I pull the lever the pads move a little and rather than fluid moving into the reservoir from the bleed cup the lever will return and no fluid drawn into the system. Using the shimano method of squeeze, open nipple, close nipple, release, it is possible to make the lever stay at the bar (effectively a vacuum in the system?).
It is possible to reverse bleed with a syringe and get fluid back into the cup (it did look a little dirty).
Any ideas? Or is it fubared? I know shimano brakes aren't available in parts, so is it time to replace? Probably with xt, I think, seems more sensible.
a little bump to see if anyone has any ideas this morning?
I reverse bled my M985's, I found it much easier than pumping it through using the lever.
I'd look at the other end for problems. The pistons might be stuck to the square seals, so they'll move some but not auto advance. Drop some mineral oil behind them, and hold one back with a ring spanner or tyre lever while letting hte other one move. You should find it pops free... Don't let it too far out! Keep working them while flushing the gunk off until they move freely and then try bleeding.
And if that don't work.. They've a 2 year warranty.
On the new ones you aren't meant to
until they towards the end of the bleeding procedure. fluid wont go through as it gets air locked and the air pushes the fluid back up when you release the lever.shimano method of squeeze, open nipple, close nipple, release
They can be fiddly so I just pump fluid up from the bottom with a syringe, then lock the nipple, back pressure the syringe and jam the syringe open so its holding a large vacuum. then open and close the nipple rapidly to suck the air and fluid back down. For me it works better than their official method which I couldn't get to work to save my life.
which XTR brake do you have? different methods for old and new versions.
Thanks folks.
I can reverse bleed it to make the lever firm. But can't advance the pistons for what ever reason. Before this bleeding procedure I had worn a set of pads in one ride and pushed the pistons back in with a suitable tool. I guess they may have got stuck with muck at the same time.
bikeWhisperer - I'll try the piston lubing / massaging for certain.
Wibble89 - I think the one thing I didn't try was sucking the fluid down from the calliper end. I'll give that a go at as well. Do you do this with the lever squeezed or not?
it's the new 988 trail brakes btw.
Lever in normal position with lots of fluid in the bleed cup. Keep an eye on the level as it can go down quick.
Edit: if you get it bled and feels firm with the bleed block but the pistons wont advance when you put pads in, as though you have sticky pistons, adjust the lever so it is full out/reach and bite point is at a minimum movement. It should allow more fluid to move when you pull the lever and push the pistons out further to over come the resistance of the piston seals.
It won't take more fluid form the reservoir. Looks like there's 2 tricks to try and overcome this piston issue (if indeed it is a piston issue).
I'll try those and then I've got an slx lever kicking about I can try to work out if it's definitely a piston or lever issue.
thanks.
swap both brake cables over (EG, front caliper on left lever to front caliper on right lever )to see if its the lever or caliper, you have to rebleed but it will save buying wrong end/messing in the long run.
OK folks, for those of you interested, I swapped out the lever for a spare SLX one I had kicking about. Problem fixed.
Even with the lever off the bike and the reservoir cap off, the lever wouldn't move freely. Definitely something fubared inside the lever.