Alright, I got a powermaster III unit off of ebay a few months ago. It appears to be a Prior rebuilt unit. It has the nutless accumulator, as well as a few labels on it that have the writing warn off of them. So I finally got around to installing it a few months ago. The install went good..about an hour total. I got all the switches reset..had a few problems with the brake switch but it's ok now. I found when I was bleeding the brakes that the accumulator was leaking, so I tightened it down and the leak went away. I also found that one of the rear calipers was siezed. That is also fixed now as well. But after doing a full bleed, the pump still runs after every 2 pedal presses. I'm thinking it's maybe the pump relay, since that is something Prior doesn't replace when the reman. units. Does that sound right? It feels like it's building up good pressure. And neither the Brake light nor the Anti-lock light are on anymore, like they were with my previous unit. I just wondered what the experts thought :) Thanks for reading!

The only other identifying trait of a Prior unit is the motor is usually painted gray. I have seen these accumulators on other non prior rebuilds so they are available somehow and its possible its been replaced by iteself. Especially if it wasn't tight.

The relay probably isn't the issue. Either the pressure switch calibration is off, or the accumulator is low on charge. Not knowing the history for these two items there is nothing you can assume about their condition. Without special guages to monitor the hydraulic pressure in the unit, there is no way to know without just trying. The only other problem could be some trapped air. It is possible, even with a good bleed that some air is stuck. It may only be a matter of driving it to get it out. Also you can try purging the solenoids by stepping hard on the brake pedal and turning on the key. The solenoids will make a loud clicking/clunking sound. Do that about 10 times and it may help.

Thanks for the info Chris. I'll try what you suggested. I was hoping it wasn't the accumulator..but I guess in the end it will probably be the accumulator. Does anyone know the specs on the accumulator? Like how much pressure it has to build? I might look elsewhere (other than GM or Prior) for an accumulator, since they are a common item. Thanks

I don't know where else you will find one. I'm not sure if any of the Teves systems use this high of pressure or not. I'm sure there is something. The pressure switch kicks on at 1800 psi, and then off at 2400 psi (iirc its pretty close, besides whats  100 or 200 psi at that level)

I know the accumulator is charged to 207 bar though... so if 1 bar =29psig then.....uh that can't be right. Well anyway. Maybe thats the max pressure. The Powermaster 1 on the Turbo Regals is only like 35 bar, around 500 psi so it won't work.

The pressure relief valve will blow at 2800 psi.

I remember reading if the accum pressure is below 1600 psi it's time to replace it.

http://www.chromatography.co.uk/Techniqs/Other/Pressure.htm

:D

Accumulators are used in MANY industrial applications. So it just comes down to finding one with the right pressure stats and mounting style. :D

Cool! That 207bar must have been the maximum pressure rating for the accumulator I was thinking of. Good luck and let us know what you find!