is my powermaster going out

[datant69]

ive contemplated replacing it but rarely drive it, in fact i've put less then 9K on it since ive owned it. i blew the fuse awhile back replaced it and the pedal has been hard as a brick with the exception of a few times. Now i've read that the fluid needs to be replaced and how horrible the power master unit is. Before i replace the power master unit i wanted some opinions. I have a guy not to far from me who had one he pulled from a junker but never got back to him about it.not sure if he sold it or not but i've been wanting to put some miles on it and before i do i wanted to replace it. also what is the difficulty in replacing it?

 

[azbob]

Here is a good explanation of the basics plus some on a possible conversion to vacuum.
Brake System

 

[GullsGN]

The most likely culprit for the hard break pedal is the accumulator ball. In 25 years and 150K miles I have replaced this twice. Takes about 2 minutes and 1 wrench to do. I have never completely replaced the brake fluid in my GN in the 25 years I have owned it. I have sucked out the fluid in the master cylinder tank and replaced it with new fluid maybe 3 times.

 

[datant69]

is that part available at any local auto parts store?

Wanted to ask since u guys know the most about this. I would call my local autozone but with my luck and the last few experiances they usuaally don't know what the hell I'm talking about. Also replacing the ball doesn't require any special attention like don't do this or bleed it like a master cylinder. It may seem like a crazy? But I'd rather know before hand then to learn by trial and error

 

[TurboDave]

You can get the accumulator from Kirbans. The procedure is to pump the brake pedal at least 10 times with key OFF, this releases system pressure. Then unscrew the old acc. and quickly screw in the new on so only a drop or two of fluid comes out. Once it's tight, turn key on to repressurized system. Should be good to go.

DO NOT DRIVE THE CAR ANYMORE WITH THE LIGHT ON, OR YOU WILL CAUSE FURTHER MORE EXPENSIVE DAMAGE.

 

[Ttype6]

PM sent.

 

[datant69]

after eating dinner with family i decided to hit a local chain auto store and all i can say is that toilet float looking ball is expensive as hell. guess i'll do some digging around and see if i can find one cheaper. they only seemed to have new ones or should i say rebuilt ones and there was only a 20.00 differance between the whole mastercylinder and the the float ball. i'm sure they are rebuilt but still i thought i would be cheaper.

 

[aminga]

Was the pedal completly hard or was it just hard at the initial application of the pedal. It doesn't mean that it can't happen but I've never seen the accumulator ball cause a hard pedal that stays that way.


Most often the accumuator will cause a momentary hard pedal that gets better as the motor starts up. Long before the pedal gets hard enough to notice it will start to flash the brake light on the initial application of th pedal

Pump the pedal a couple of times (key on), and verify the motor runs. If it doesn't look at the fuses If youre popping the fuse the motor needs to be replaced.

 

[TurboDave]

If youre popping the fuse the motor needs to be replaced.

Not necessarilly. That was the point of the tests I'm having him do. There are other things that can cause the fuse to blow. My experiences prove this out.

 

[aminga]

I'm listening

 

[TurboDave]

I'm listening

The two times I've seen fuse blowing issues, it was a bad pressure switch, which in turn was causing the motor to run far too often and too long, and for no reason. Over taxed the motor and drawing excess current.
Replaced the pressure switch and fuse, all's well. Motor/pump wasn't hurt.