Powermaster Symptoms

[rb68rr]

Brake pedal went almost to the floor the other day! Had just enough to stop! With the key off and pump them up 10 or 12 times, they will build up but then fall back to the floorboard. BTW, the first couple of pumps you can hear a loud..... Whoosh! Turn the key on and the motor runs for about 15 seconds and shuts off. Press pedal and down they go again! Motor comes on for about 5 seconds and shuts off. I can't see any brake fluid leaking anywhere. The passenger side of the master cylinder looks to have lots of air in the brake fluid, really frothy looking. Is this a bad master cylinder or what?

 

[aminga]

The Pedal going to the floor is usually a symptom of air in the brake lines just like any other booster type.

 

[TurboSlacker]

Sounds like the accumulator to me. Swap with a known good one and see if it fixes it.

 

[TurboDave]

Doesn't sound much like an accumulator symptom. Sounds more like a bad internal M.C. leak.
Fluid levels look OK?
When you apply the brake pedal with key on, what happens to the fluid in the two sides of the reservoir?

 

[rb68rr]

Fluid level looks ok except for the frothy look on passenger side. Haven't tried looking at levels braking with key on with lid off.

 

[GN owner]

"Doesn't sound much like an accumulator symptom. Sounds more like a bad internal M.C. leak."

X2

 

[TurboSlacker]

"Doesn't sound much like an accumulator symptom. Sounds more like a bad internal M.C. leak."

X2

Ouch, very likely and more of a pain in the butt. The passenger side fluid of the reservoir comes from the accumulator thru the master cylinder of course. When changing accumulators and cycling it, the result I've seen is always fine bubbles in the fluid that looks as you described. After one cycle I replace the fluid from that side, cycle again, then crystal clear fluid!