mastercylinder question?

[lahnen]

its been a long time since i have had to mess with mastercylinders, but i'm on my second new one on my suburban. after bench bleeding and installing, i'm having problems getting the rears to bleed out and to work. when pushing the pedal, fluid is shooting back up into the front brake reservoir. i didnt think this was supposed to happen, but i got 2 in a row from 2 different stores now that do the same thing. should i try a third mc or look into something else. everything is brand new except the booster and porp. valve, but they appear to be workin properly.

[75chev4x4]

Are you meaning that when u push the peddle down to bleed the system the fluid in the master is shooting up? This is normal dont worry about that. With the rears check that your button on the proportioning valve is pushed in. This will trip sometimes if it senses that the rear are loosing fluid and cut them off and can be hard to get fluid back there when bleeding.