Rear brake bleeding

[JetDriver]

I'm bleeding my brakes.  The front ones go okay, but I've got a problem with the rear.  I opened the bleeder valve, and my pump got nothing but air.  I eventually pumped the old fluid through with the brake pedal.  I then filled the reservoir with fresh fluid, tried the pump again, and got nothing but air.  So I tried the pedal again, only this time it does nothing.  The pedal moves, but the fluid level in the reservoir does not move.  What do I do now?

[9Ball]

you've got air in the system.  Two ways to do this...one is to force fresh fluid into the bleeder and pushing the air out into the matser cylinder (make sure there's room in the M/C so you don't overflow it).  I use a large syringe and tubing.  If you ask your vet they usually give you one for free.  These are the syringes that have tapered nipples (oh, baby), not needles.

Second is to apply vacuum to the bleeder and pull the fresh fluid and air into the bleeder and out of the system.  You can actually do this with mouth suction as long as you have a long enough piece of tubing so you don't inhale brake fluid.  I use a large veterinary syringe and surgical tubing, then install speedbleeders for the next fluid change.  These are really great and are almost zero mess if you use the bladder bag.  Others invest in a mityvac...much more expensive and not really needed, although they do work very well.

[Westsider]

Hey Jet, what i do is get a large syringe from a local feed store like a cattle size one or so. get some ,i think 5/16 id clear tubing from auto zone or whoever,and suck new fluid from the bleeder with the hose connected to the bleeder,put a box end wrench on the bleeder first so yo can shut it after vacuming the fluid throgh. that big sryringe will pull a heck of a vacume..this works super efficient every time. careful not to empty your reservoir  /its nice to have someone filling your reservoir while you are pulling fluid through from the bleeder/  will also work perfect on clutch..do it all the time ,can replace all brake and  clutch fluids in about thirty minutes , with rock soild levers and pedal..
remember to have the bleeder closed whenever your not pulling a vacume with the syringe...you will see the clean fluid coming through the clear tubing.

[shortleg]

  I have found useing a Mity Vac is the way to go.
Just did all the fluids in about 30 or 40 min.
          Shortleg[Dave]

[JetDriver]

Thanks for the replies, guys.  I think I must have miscommunicated.  I have a mityvac.  All it draws is air.  So I used the brake pedal to pump the old fluid through, and purposely emptied the reservoir until it drew air.  Then I re-filled the reservoir with fresh fluid, and again tried the mityvac.  All I got was air.  So, I thought I could use the brake pedal again.  I exercised the brake pedal, and this time it wouldn't move any fluid either.  I pump away, and the reservoir stays full.  So, I suck and I blow- nothing works!  

[designer]

try pulling a vacuum and holding it.... then pump the handle.... this should give the fluid motivation.

If that doesn't work try pushing from the  caliper side with pressure from the vac.  it may prime the valve enough to get it going again.

[Bobbo]

I use a Mityvac for both bikes and cars with good results.  Make sure your pedal is all the way up (not depressed) when you are using vacuum on the bleeder.  I also put some grease around the base of the bleeder to keep air from flowing in from the threaded area, to eliminate "false" bubbles.

There should be no reason you can't draw fluid even of the lines and caliper are empty.

[Patrick]

1. fill the master cylinder
2. pump pedal and hold
3. loosen bleeder
4. tighten bleeder
5. repeat until no air comes from bleeder..

Don't let master cylinder become dry and don't release pressure on pedal until bleeder is closed.. This may take a helper,but, it doesn't take long.. Don't spill fluid on anything..

[JetDriver]

Thanks guys.  Don't know what I had, air bubble lodged, tube not tight enough on bleeder valve, don't know.  I kept monkeying with it, trying your suggestions, and it finally started drawing fluid.  All seems to be okay now.  Thanks again.

[Bobbo]

1. fill the master cylinder
2. pump pedal and hold
3. loosen bleeder
4. tighten bleeder
5. repeat until no air comes from bleeder..

Don't let master cylinder become dry and don't release pressure on pedal until bleeder is closed.. This may take a helper,but, it doesn't take long.. Don't spill fluid on anything..

The only caveat to this method is to be careful when pressing the pedal after opening the bleeder.  On an older master cylinder, there can be a buildup of grit past the normal travel of the cup.  If you drive the cup into this grit, it can plug the valve or cause wear on the cup.  It is best not to move the pedal past the normal travel.

[vanagon40]

1. fill the master cylinder
2. pump pedal and hold
3. loosen bleeder
4. tighten bleeder
5. repeat until no air comes from bleeder..

Don't let master cylinder become dry and don't release pressure on pedal until bleeder is closed.. This may take a helper,but, it doesn't take long.. Don't spill fluid on anything..

I agree with you Patrick, except that I switch 2. and 3.  This is not a difficult procedure and I do not understand all the folks with Mity Vacs, hypodermic syringes, etc.

As you suggest, this is a two person process, but I installed speed bleeders on my bike as to make it singular.  As with the rest of my vehicles, my wife cringes every time I start working on brakes.  "PRESS...RELEASE...PRESS...RELEASE...[repeat 20 more times]."  But the good thing is, my wife is really good at following the procedure and a really good sport (and on a side note and much to my wife's chargrin, she is the absolute best tow strap/tow chain leader I have ever followed).

I believe it was an old Triumph (sports car not motorcycle) manual that described the procedure of bleeding brakes as starting with "a hose, a jam jar, and a helper."

[JetDriver]

As you suggest, this is a two person process,

This is why the Mity Vac! 

[Patrick]

I still do it this way after doing this kind of work for 50 yrs and do it alone.. It just takes a little extra to figure out how to keep pressure on the pedal.. I have a pressure bleeder, but, I hate it, its a PITA..

[9Ball]

I agree with you Patrick, except that I switch 2. and 3.  This is not a difficult procedure and I do not understand all the folks with Mity Vacs, hypodermic syringes, etc.

If you have a dry system (such as new brake lines) or let the M/C suck in air then the speedbleeders don't help with efficient bleeding.  This is where the syringe or mityvac method allows you to displace the air so you can bleed the brakes.  Hopefully this adds to the understanding of the recommendations given.

YMMV....