question on powermaster light?


Aug 23, 2008
I just took it out of the garage after winter storage. No hard brake pedal feel. Still stops in the driveway, brakes work. But when I press the brake pedal fast light come on, when I let go light goes off.
Sounds like it's time for a new accumulator ball.
Remember also it's very important to change the brake fluid in the reservoir every so often
to keep it clean.
The light comes on hard pedal press, Not soft pedal press. With engine off, pressed the pedal 10 times to depressure the system, checked fluid Driverside was full. Full on the passernger side and alittle milky. Took half out, turned ignition on/engine off. Powermaster motor works/kept it at half way til the motor shut off.
KC87 gave some sound advice. What accumulator ball do you currently have?
New switch too.
Might want to put new seals inside too. If it's leaking down internally, you'll be able to tell if it cycles the pump while it's just sitting there doing nothing (key on ofcourse)
It was good advice. I agree, My fluid hasn't been changed in a few years. The one Highwaystars sell's. I replaced maybe 14 years ago. And replaced the Pressure Switch a little after the accumulator ball was replaced. I'm lucky the motor never gave me problems, so far. I was thinking maybe flush & depressurized until the fluid comes clear. Maybe that might fix the light issue, Might clean the inside of the accumulator ball. I'm going to try that first before spending $400 on the ball. The brakes feel normal. thx for helping. I'm not driving it yet.
Letting the fluid get dirty on a powermaster system will eventually bite you. Once you get it running right again, put it on a maintenance schedule and change the fluid at least once a year. I used to do it twice a year same time I change engine oil, was easier to remember that way! I just sucked the fluid out of the reservoir and replaced with fresh fluid. Only took a few minutes to do. Learned that trick from RC. Good luck!
since most folks do not have the Kent-Moore tee and gauge setup to check system pressure, operating and cycling, there is a basic bench test to confirm the accumulator has lost charge.

Brake fluid deteriorates the membrane within the accumulator, causing it too gradually loose its charge pressure over time (years). there is an internal metal plate covering part of the membrane. From the accumulator threaded port, insert a finish nail and you will hear a metal on metal sound when tapping the nail against the plate once you drain the fluid from the accumulator.

you have to work a little bit to drain the brake fluid in the accumulator once removed. shake it in a container as draining something without a separate vent takes a little time as you shake out the fluid.

The OE all black accumulators made by Singer (sewing machine co) and the 2nd version with yellow warning print on end (with the hex nut on the outside end) have the metal plate. I expect the Hydac accumulators to have it well as accumulator construction is pretty basic.

secure the nail in a vice. once you check the internal distance to the metal plate from the outside of the accumulator, if you can use your weight to push the accumulator down about a 1/4 inch to the surface of the vice, the internal pressure of the accumulator is too low. A replacement should be purchased.

Vendors and ebay have the Hydac accumulator. check around to learn who has what in stock and how much.


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depressed the system 5 times, nice n' clean now when its depressurized coming from the acummulator. I ordered a new brass proportion valve, I didnt know they give problems( the original) & screw's up the acummulator ball inside. please help in my other thread I just posted on replacing the proportion valve. There was even a recall on the stock one.