brake booster

85 625 csi, engine off firm brake pedal engine running pedal fades 1/2 way down then keeps going to the floor.

can any one tell me what is actually happening with the hydro boost system. and if any one knows what will have to be replaced or serviced?

i already own a master cylinder for this thing that i'm sure isn't the problem.

i am a toyota tech with 26 years exp. but haven't dealt with this type of system before.

thank you

i heart about this kind of problem...you have to check with mechanical and verify what's going on. i can help with parts that i found in auction http://www.easyexport.us/?a_aid=4bead65889ce2file:///H:/DOCUME%7E1/admin/LOCALS%7E1/Temp/moz-screenshot-3.jpg

I found same problem while the brake booster once leaked after accident, I replace it with new one.