Proportioning valve issues.

[mpierce9]

I ran into a similar issue a few weeks back. My solution was
1. Clamp down the Combo valve button.
2. Remove the MasterCylinder cap
3. open the rear bleeders (both sides)
4. monitor the MC fluid level
It took 48 hours to get good fluid out.

All this should be able to be resolved with a two person bleeding job much quicker. I was told that slow 1 pedal pump bleeding works best because the volume of air stuck in the line after making such major changes.

I was making the mistake of doing a two person bleed job allowing the person that pumped the pedal to pump it up multiple times to build pressure. This was causing my issue that filled the line with air and didn't allow fluid to the rear.