das_pelko,
I canceled out the brake lines altogether.
the way i did it is cap the master cylinder ports.
in this case, when pumping the brakes the pedal should go firm, as air doesn't have anywhere else to travel, but it doesn't.
i tried this with multiple master cylinders, all of which were bleeded out successfully with a couple of squeezes.
the pedal still goes down and the booster still makes the hissing noise on depressing.
and the way i see it, there is no way that push rod inside the booster can deliver pressure to the master cylinder.
the rod inside the booster must have either offset somehow someway or broke, as the diameter on the end I don't see how it conforms to the diameter on the m/c.
this would explain why bleeding out the brakes is such a PITA and takes so long.
there is no pressure at all coming from the m/c.
and since the chance that 3 master cylinders would be borked (2 come from the junkyard) is small.
when I bleed out the master cylinders, there is LOTS of pressure on both lines.
so the diaphragm/something else on the booster is borked, therefore the booster needs to be replaced.
the problem is the brake booster 99%.
I'll pickup another m/c from the junkyard just in case though (1%).
I'm going to pick up a couple of boosters and master cylinders from the junkyard, and if all is well I may just invest in new ones in the near future.