Can't bleed rear brakes

[cleanfreak62]

Hi guys, recently had issue with rear brake pedal rock hard and no rear brakes. Had the front forks serviced and told them to look at the issue. I was not a Yamaha dealer. The forks came out great but now I have a completly soft rear brake pedal. They tried to bleed it but told me that it may be an ABS issue. No lights, no codes. Now my rear master cylinder is full but I can't bleed the brakes even with a vacuum tool. Very little if any fluid coming out of caliper valve. Any suggestions on what may be wrong. I have the service manual but I can't seem to find any fixes. Very frustrated. Front brakes work perfecly fine.

 

[finnish v-max]

Have you tried cleaning the valve and reverse bleeding?

 

[cleanfreak62]

Have you tried cleaning the valve and reverse bleeding?

I am not sure what you mean but the valve is clear. Do you mean pushing fluid from the valve back up into the fluid resevoir? If so I have not but I will give it a try.

 

[finnish v-max]

Yes pushing fluid from the bottom is easiest way to get all the air out of the system.
Never done it whit abs but i would imagine it would be same than non abs systems.

 

[cleanfreak62]

i took air and blew out the lines from the caliper to the fluid resevoir. All clear. Filled up the fluid resevoir and I can't get fluid back down to the caliper even with over 20 pounds of vacuum. It seems that there is some kind of check valve that is not letting the fluid come back down to the caliper even when I apply the foot pedal.

 

[MaxMidnight]

The Service Manual (pp 3-24) specifies that the front brake should be bled first and then the rear. I'm reading this as you must bleed both systems to ensure that the ABS unit is air free.
See attached

 

[02GF74]

Ah the joys of complex electronic components.

No idea if this will work but maybe you need to have the ignition on so the ABS is powered?

 

[cleanfreak62]

Ok I will give it a try thanks

 

[02GF74]

I'm offering a suggestion, no idea if it will work but can't see it can make it any worse.

Ideally you want somebody who has gone through this.

I'm gen 1 so no fancy electronic wizardry.

 

[Fire-medic]

While I am a proponent of the reverse-bleed, I think it should only be done with non ABS systems.

 

[Nsubs]

Hi guys, recently had issue with rear brake pedal rock hard and no rear brakes. Had the front forks serviced and told them to look at the issue. I was not a Yamaha dealer. The forks came out great but now I have a completly soft rear brake pedal. They tried to bleed it but told me that it may be an ABS issue. No lights, no codes. Now my rear master cylinder is full but I can't bleed the brakes even with a vacuum tool. Very little if any fluid coming out of caliper valve. Any suggestions on what may be wrong. I have the service manual but I can't seem to find any fixes. Very frustrated. Front brakes work perfecly fine.

pressurise back feed, you got a block, then full change. failing that, you have a collapsed hose.