Thanks, Hopefully I can get it figured out. I have a working used unit coming in so I can swap parts on.
Mine just stopped working in my '86 GN too. The reservoir looks full, all cavities. The brake light stays on - all the time. The fluid looks nice and clean (no hint of black crud) and no external leaks. I do not hear the motor running at all but have not made it through all of the diagnostics.
I want to learn something, so I have ordered an accumulator and motor EH. I was wondering about where to purchase the master cylinder seal kit - Partsamerica, Karps or MBM? Who do you think has the most complete kit? Do I even mess with the master cylinder? The car has 94K miles on it
Thanks,
Bill
I am not able to be able to do a lot of the tests. However, My brakes have been working fine all week, and then yesterday I got the hard pedal again. It is coming on sporatically. Most of teh time evrything is fine, then out of nowhere the pedal will be rock hard for a couple minutes, then shortly it will go back to normal.
Can the motor work occasioanally? Couls the switch or ball work like this as well?
Thanks.
Matthew
I am not able to be able to do a lot of the tests. However, My brakes have been working fine all week, and then yesterday I got the hard pedal again. It is coming on sporatically. Most of teh time evrything is fine, then out of nowhere the pedal will be rock hard for a couple minutes, then shortly it will go back to normal.
Can the motor work occasioanally? Couls the switch or ball work like this as well?
Thanks.
Matthew
My Powermaster problem had the identical symtoms. The motor would work as normal for long periods and then would not. Out of frustration and weeks of doing diagnostics and switching out parts to find the problem, I tapped the side of the Powermaster motor one day with a small hammer when it wasn't working. Like you would with a heat soaked starter. It worked. Turns out the motor was fine, but the relay that runs the motor was only working intermittantly. In my case, a new motor from Hank Terry solved the problem immediately.
GM PowerMaster Sales
The unit will not cycle on it's own after two minutes with the key on, it is after depressurizing the system. Also it only takes 10 sec to shut off after turning the key on also.
Thanks guys for your help.
Matthew
There is your answer right there. Your accumulator is dying. Your hard pedal is a classic symptom. Your time to shutoff is good, but a little too long. Replace the acc ball and that time should be cut almost in half once you get the air out of the new ball.
I think the light issue is a problem in the electrical harnes. Can't come up with a good explanation other than that. My light didn't work either when my Acc ball went.
How do you get the air out of the ACC Ball? Just bleeding the brakes? Should you bleed them with the key on so the motor still putting pressure on the system?
Thanks
Matthew
With the key off, you are pumping your acc ball down (depressurizing) and the fluid is coming out into the p/s bowl with every stroke of the pedal. Once it is completely pumped down, you should have a firm pedal and the p/s of the bowl should be at the top of the full mark. When you turn on the key, the motor will pump the acc ball back up and refill it with about half of the fluid in the p/s of the bowl. Once it does this, leave the fluid at this 'about half full' level. This is correct for the P/M.Ok, I know I am probably becoming a PITA but when pumping up my brakes with the key off, I have brake fluid overfloing from the resivor. I guess I have too much in there. But when do I know if it is to low on the pass side?
I have had this car for over three years and this is the first time I have had any PM issues. So I am definately on a learning curve here! LOL
Thanks again.
Matthew
A curious question to any who may know-
I just replaced my accumulator, and with the reservoir full, it seems as if slowly but surely over time the unit has to re-pressurize more frequently than it used to. Right when I replaced it, you could get 6-7 pumps out of the pedal before it re-pressurized, and now its down to 3-4 maybe, and it sometimes has to pressurize when I turn the car on (whereas I dont really recall this happening right after the installation)...
Any ideas? The brake warning light is off and the brakes work just fine...just concerned a little bit. Thanks.