Powermaster Problems (Please Help)

[VadersV6]

Don't ASSume. The powermaster is the whole thing. Motor/pump, master cylinder, and accumulator ball, along with the pressure switch that controls it. You can get the motor/pump assembly from Hank Terry using the link near the top of this thread. I understand that GM no longer has the rebuild kit for the master cylinder, and the accumulator balls have gone up and price, and are hard to find.

Dont be a DIck.
I followed the procedures on gnttype yesterday, and it is all coming down to either a bad accumulator (which looks new...like it was replaced with the master cylinder), or the motor isnt spinning fast enough. After bleeding pressure from the accumulator with 10 pedal pumps, it takes 12-13 seconds for the motor to cycle. Its taking a long time for pressure to build. If I push the pedal twice, the motor will cycle because the first push of the pedal drained all the pressure. The motor doesnt cycle itself after 2 minutes, which led me to step C. I need to replace the accumulator and then test again. I think I also need to bleed the front drivers side brake.

 

[J!nchu]

Sorry about the double post :frown:

 

[J!nchu]

I was looking and i have found that the raspy hissing noise is coming from that little black box (outlined), can anybody tell me anymore about what they think the problem is, what exactly that box is, or the part number for it???

The Little Box
The Little Box Up Close
Not Outlined

 

[VinsGN]

1)Upon initial start up the PM’s motor may cycle up to 4 to 10 seconds in order to build pressure. It should shut down and not cycle until the brakes are applied three to four times after initial powering. Following this the PM’s motor will cycle from time to time in order to keep pressure present. It should not continually cycle or cycle on and off constantly. (In my experiences the accumulator ball as failed if this happens)
2)You should not here any constant hissing coming from the PM. You may hear a slight hiss only when the pedal is being depressed, but the hissing should stop as the pedal stops its travel towards the floor.
3)As stated above, if fluid pukes out of the top of the reservoir then the PM has been filled too much. (Ask me how I know.)
4)Proper bleeding of the system is a must. With vacuum brakes the driver can somewhat over come the air in the system. Not the case with the PM, it will continually cycle to compress the air in the system.
5)I agree with the statement also stated above, the PM motors usually do not go bad. Its either the accumulator ball, switch or fuse.

Just keep in mind that Kirbans is to come out with a repro accumulator ball for about $100.00 this month. So stay away from the $200+ “NOS” gaugings.
The switches are on e-Bay from time to time and can be picked up reasonably, IF you keep searching and take your time. I have also been lucky enough to fine one a local parts store hanging around so ask and ask again.

Hope this helps.

 

[Ormand]

Dont be a DIck.

It takes one to know one, I've always heard. The accumulator has an internal diaphragm, made of some rubber like material. The material ages, even when the accumulator is sitting on the shelf. And the nitrogen slowly leaks out, so a brand new accumulator put on the shelf today may not be good after 10 years. They used to be easy to find, and about 50$, now they are much less common, and much more expensive. Good luck in your trouble shooting and repair.

 

[G-Racer]

Mr Real Deal,
I need a pressure switch. Can you tell me where the $18 switch can be found?
Thanks

 

[TurboDave]

Mr Real Deal,
I need a pressure switch. Can you tell me where the $18 switch can be found?
Thanks

I don't know where he's finding those either. The one's that pop up on ebay on occasion generally end up going for abou 70-90 bucks. Somebody tell me where i can get an authentic switch for $18 and I'll buy a hundred of them.

 

[Danster]

Were they $18 dollars back in 2002? That's the date when the comment was posted.


Dannyo

 

[VinsGN]

Were they $18 dollars back in 2002? That's the date when the comment was posted.
Dannyo

Excellent observation. They are way more than $18.00 presently. You’ll have to bring a gun to the deal in order to get one at that price.

 

[VadersV6]

So to anyone who knows the internal makeup of the accumulator-
Mine takes a long time, actually 13 seconds to cycle and build up all the pressure. The motor does not cycle every 2 minutes like it should...it doesnt cycle at all after the initial one. But if I press the pedal twice, it will cycle. Press it once, nothing. Press it again, and the motor will cycle. And every time it does, it does it for 13 seconds. According to gnttype, its pointing in the direction of the accumulator.
So does the motor build up pressure in the accumulator, and then the accumulator pressure gets released so the brakes apply?
I was thinking that either its the accumulator, or there is air in the lines and the motor is trying to build pressure in an air soaked line, or the motor is slow.
Should I bleed the drivers side front brake, and if so, how do I do it? Should I have the ignition on and cycle the motor before bleeding? Should I bleed pressure in the accumulator by pumping the brake 10 times before trying to bleed the line? Or should I have pressure in the accumulator when I bleed?

 

[zeus87gn]

Am I the Power Master?

VadersV6 - my PM was taking a long time to cycle as well. You may have the same problem I had. I broke down and bought the complete repair and diagnostic manual. I think Kirbans and/or Postons sells it. It may make you a PM expert if you aren't careful. I ended up rebuilding the master cylinder portion myself with new purchased parts for only a couple 100 dollars.

Check for this - after you depressurize the system, remove the reservoir cover, make sure there is good, clear fluid present and turn the key to the on position but don't start. If you see fluid coming back into the reservior through the return line, the master cylinder seals are shot and need to be replaced. Once I replaced them, my motor shut off in the correct time. I ended up replacing the motor soon after as I guess it was the next weakest link. (Thanks again to Hank Terry!)

If there is not good clear fluid, this may be one reason you are having problems. You have to keep all the fluid in good shape. If you can't see through it, it isn't good enough to keep the PM in good working order. Many overlook this and don't worry about it, I am a stickler about it.

These systems are actually quite simple. Too easy not to do it yourself. I just hope we can all keep finding all the parts.