2011 R1200RT Brake Flush Disaster!!

[Crawdad1200RT]

New to the forum.  I have a 2011 R1200RT.  I bought the bike at 33,000 miles and have ridden over 3k in the last month.  I love this bike!  But....


It was time for maintenance, so I bought the JVB productions video, went to Beemer Boneyard and got some stuff, and set out to do my own 36000 maintenance on the bike.  Everything was going really well until the very last step...  Flushing the rear brakes. 


Flushing the front went well.  No problems, very firm brake lever, I'm certain there isn't any air in the lines.  When I got to the rear brakes, however, within a few strokes, fluid stopped coming out of the bleed valve.  I was unable to build up pressure by closing the bleed valve and pumping the rear brake.  No fluid is going from the reservoir into the master cylinder (I think) and absolutely nothing comes out the rear bleeder valve.  Also, the brake calipers are definitely not compressing the brake.  There isn't any fluid leaking, so I don't think I have blown a line. 


I am pretty sure I have introduced a bunch of air into the system and I cannot get it out. 


Any help would be appreciated.


JC

[David.]

The Haynes manual recommends the following procedure.

Remove the brake pads & brake caliper.
Force the pistons back into the caliper & hold using a brake spreading tool.
(A small G clamp & a piece of wood of the appropriate thickness works for me).

This technique is advised by BMW, it reduces the fluid volume in the system & therefore the chance of air too.

Repeat the bleeding process & see how you get on.

[michaelc2710]

if that doesn't work you can try a syringe and a rubber hose onto the nipple and back bleed the system.
This will push the air back up to the reservoir 

[julianq]

Pushrod/linkage dropped off the brake lever?

[Crawdad1200RT]

Thanks for the quick responses. 


I pushed the calipers back in with door shims when I did the job originally.  That held them in place.  When I did this, the fluid level in the reservoir increased, confirming I had forced fluid backward.  Now it doesn't because there is so much air in the system (I think)


The linkage is connected properly, but that was a good suggestion, because it almost feels like that.  If I play with the lever enough I can get a tiny bit of air to come out the bleeder, but there isn't enough action to get any fluid out.


I'm going to try the syringe-backflush method today and see if I have any luck.


Any other suggestions will be welcomed.


Thanks,
JC

[exportman]

Hello


Sometime forcing the brake pistons back into the calipers sends a large volume of  fluid back into a master cylinder  this can damage the master cylinder seals or force dirt  into the chamber  so you are not getting any pressure as the fluid just flows past the seals.  Maybe this was only on  older vehicles but I always crack the bleed nipple before pushing pistons back.


On cars I use a system that uses air pressure to force new fluid through the brake lines that way fluid flows past the rubbers in the master cylinder in the correct direction  and any crap is pushed through and out.  It would probably work on the rear brake as the reservoir has a round  cap.

[Sprintgull]

I had a similar problem with a Triumph and it seemed to be air in the caliper.  From memory (it was a few years back)  I took the caliper off and gently just rocked it back and forth to dislodge any air bubbles that may be stuck in the corners.  Then with the nipple at the top bled the caliper using a vacuum bleeder.  You may need four or five hands to do all this!  Then with the caliper back on the bike I sucked new fluid through as normal.

[Crawdad1200RT]

I got it figured out.  Thanks for the help.  Here was the solution.


First, I unwound the kink in the reservoir hose.  DOH!!  I guess while putting on the lid, I had spun it around a few times. 


Unwinding the hose allowed me to...


Backflush the system with a 30cc syringe and some tubing.  While I was doing this over and over, I gently worked the brake pedal.  Eventually, I started to feel a little pressure at the syringe when I worked the brake pedal.  Once I was confident that everything had at least a little bit of fluid in it and that I had backflushed the system enough (about 5 times through the syringe), I switched it up and did a conventional brake bleed.  I got a nice pedal, took it for a ride, and then re-bled it.  It's working fine now and I know more about my rear brake than I ever wanted to.


I think if I hadn't kinked the hose, I may have been able to just do a normal bleed, albeit a long one, but I had gotten so much air in the system that I pretty much had to start from scratch. 


Thanks for the help.


JC

[Sprintgull]

Yep that'll do it!!  Glad you are all sorted.

[michaelc2710]

Well done,

[julianq]

Nothing like a mistake made, will not do it again and may help someone else.  :clap: :clap:

[LAF]

Great job in working through it.  I ran a reservoir dry one time and it was a pain to get the pedal back.  It got there but with much of the pain and anxiety you went through.

Glad you got it fixed.

[Our Gee]

Might also be worth considering an ABS Unit flush as I am reliably informed that a conventional Front and Rear fluid change does not remove the fluid and any contaminants such as water from the unit which can cause problems and possible unit replacement at high cost. Unfortunately this, in most cases is a dealer job. I had this task carried out on our Twin Cam recently at a good independent for around £40. See thread on page 2 of this maintenance section.