Hard brake pedal

[Lawrence Albert <l.albert@morehead-st.edu>]

Last year my father-in-law gave my wife his '86 5000s, and since then
I've been trying to put the brakes back into working order. So far I've
put new seals in the rear calipers and replaced the pads and rotors all
the way around. I replaced the master cylinder and all of the brake
fluid. I also had the hydraulic pump replaced after it seized up. Now
the brakes work really great some of the time, but sometimes the pedal
is hard as a rock, and of course the warning light flashes. Sometimes
the pedal will be hard for a few minutes and then it will sink down a
bit and the brakes will work normally, except that when I push real hard
the warning light comes on. I suspect that the problem is with either
the hydraulic servo or the pressure accumulator. The brakes could also
use a good bleeding, I'm sure, but I've still got the intermittent hard
pedal problem. I disconnected the return line from the servo, as per the
Haynes manual, and the fluid did not leak out of the hole, which
according to Haynes means the servo is OK. But I'm an shade tree
mechanic and I'd like some wisdom from a human to back it up. Can anyone
help me confirm which of these two parts I really need? I'd be ever so
grateful!