IHADAV8.com - Turbo Buick Tech, and Nonsense

Tech Area => General Buick Tech => Topic started by: slojim on May 19 2012, 07:11:55 PM

Title: another powermaster post
Post by: slojim on May 19 2012, 07:11:55 PM

GN's been sitting for 4 years since I  moved to Indiana, and now I'm moving to Houston.  (I just realized I'm 10 minutes from PTE, oh well).  It started up fine and seems to run ok, but the powermaster won't shut off unless I unplug the motor, or unplug the grey brake switch.  Both shut the motor down.  The troubleshootin g guides I could find reference special GM tools.  My brake light is not on.  The pump pumps fluid out of the reservoir, and the levels seem to hold (or at least change slowly) when off.  The switch seems to always read ~2.4ohms across all 3 pins, any combination.  I would think if it were the switch, I'd get a brake light, so maybe its the motor.  Before I do that, the fluid looks like crap, so I will flush it out.  Any input?  I need the brakes to work well enough to stop the car when I load it on the truck.
On second thought, I'm going to check the brake light also.  That might explain why I don't line up with the troubleshootin g guides.

Title: Re: another powermaster post
Post by: slojim on May 20 2012, 09:15:31 PM

well, I don't know why, but the brake light is coming on now like it should.  I flushed the MC a few times and re-ran the PM motor, so I think I have clean fluid in there.  I flushed only one brake line before the storms rolled in - rear passenger.  I still have a motor that won't shut off and weak brakes, so I ordered rebuild service from rock-auto. It was right at $230 with master cyclinder, but they only had one left at that price - it was marked wholesale closeout.  We'll see. 

Title: Re: another powermaster post
Post by: Steve Wood on May 21 2012, 12:05:43 AM

I hope that fixes the problem.  It's been a long time since I messed with the PM so I don't have any useful tips.  that was a good price from Rock, imo.

Title: Re: another powermaster post
Post by: gbsean on May 21 2012, 08:25:37 AM

chances are if the motor keeps running the acumulator ball is shot and not holding pressure...

Title: Re: another powermaster post
Post by: daveismissing on May 21 2012, 07:05:34 PM

If the motor pumps up to shutoff pressure it will shut down. If the accum is totally shot it should short cycle (buzz?)
Its leaking down somewhere, motor internally or mast cyl., unless the switch is bad.

I'm tempted to start making up those PM tools, not much to them. 

Title: Re: another powermaster post
Post by: gbsean on May 21 2012, 07:23:30 PM

check this link

http://www.gnttype.org/techarea/brakes/brakespage.html (http://www.gnttype.org/techarea/brakes/brakespage.html)