Another brake bleed/MC/Booster problem thread

[JL1RX7]

Just finished doing a 929 MC and booster swap into my '89 GXL. The booster is a used unit and the MC is a new aftermarket unit from Raybestos. Bench bled the MC until the piston couldn't move <1/16" with the ports plugged. Installed the MC on the car and bled all the lines in the proper order and guess what, squishy pedal! I've since removed and bled the MC again (with the same results), reinstalled and bled each line probably a dozen times with no perceived change. Every now and then I'll get one tiny, tiny bubble from one of the lines. So do I just have a stubborn air bubble somewhere or is something else up?

Other info:
1) Using a Motive Pressure Bleeder.
2) Brake fluid is probably >2 years old but it wasn't opened until last week.
3) Booster plunger has maybe 1/4" inward/outward play (pedal movement before the plunger starts to move, not distance between plunger and MC). I'm not sure if this is normal or not because is my first experience with a double-diaphragm 929/TII booster.
4) Pumping the brakes does nothing for feel. There's no engine installed in the car and it's possible the check valve is bad. I would think pumping the brakes would make the pedal stiffer.

Other thoughts?

[infernosg]

Just finished doing a 929 MC and booster swap into my '89 GXL. The booster is a used unit and the MC is a new aftermarket unit from Raybestos. Bench bled the MC until the piston couldn't move <1/16" with the ports plugged. Installed the MC on the car and bled all the lines in the proper order and guess what, squishy pedal! I've since removed and bled the MC again (with the same results), reinstalled and bled each line probably a dozen times with no perceived change. Every now and then I'll get one tiny, tiny bubble from one of the lines. So do I just have a stubborn air bubble somewhere or is something else up?

Other info:
1) Using a Motive Pressure Bleeder.
2) Brake fluid is probably >2 years old but it wasn't opened until last week.
3) Booster plunger has maybe 1/4" inward/outward play (pedal movement before the plunger starts to move, not distance between plunger and MC). I'm not sure if this is normal or not because is my first experience with a double-diaphragm 929/TII booster.
4) Pumping the brakes does nothing for feel. There's no engine installed in the car and it's possible the check valve is bad. I would think pumping the brakes would make the pedal stiffer.

Other thoughts?