Troubleshooting powermaster problems

B

Beamer

Member
Joined
Feb 28, 2005
Is there a place to help me determine what may be wrong with my powermaster?

I will check the GN/TTYPE.ORG site later.

Mine started acting up on me a while back and I am nervous to take it out right now. It began by when I noticed that when first applying the brakes, it did very little and then a second later - it worked just great. I do not remember ever being a delay like that in the 4 years of owning the car.

I really like the idea of keeping this system if it is feasable. It works like a champ.

The most recent time out, it actually went dead pedal on me a few times and then caught after a slow stop.



Thanks in advance for any help,
Mike
 
Just an idea....
This thing uses an electric motor to provide assist instead of the vacuum booster. Seems to me that the motor is not running all the time needed as it should. You got dirty electrical connections or faulty/dirty pressure sensor or motor is about to poop out.
There are two fuses to the powermaster. One is clearly marked and other I forget what is says but may be shared with dash illumination(not 100%).
 
86GN-862+2 said:
This thing uses an electric motor to provide assist instead of the vacuum booster. Seems to me that the motor is not running all the time needed as it should.
Click to expand...

Incorrect sir. The motor is not supposed to run contuniously and will not take it for long.
It will only run when the switch tells it to.
If he is still getting brakes, the motor is still working correctly.
The problem is the switch is confused because the acc is about to die.

OP,
You have the symptoms of the dying acc ball.
Run through the diagnostics to prove it.
Pay close attention to the section about INTERNAL LEAKS.
If you don't have any, 9/10 it's the accumulator.
 
There is a black wire on the firewall that is the ground .Kinda between the drivers valve cover and the powermaster unit .A 10MM screw is holding it to the firewall .Normally 2 wires going to it.It is very common to loosen and cause this problem.Also if you havn't changed the fluid in the last 8 months get a turkey baster and suck the old out and replace it a couple of times
 
That is clearly the accumulator as Zeus indicated. Had one die on the way home in big-city-rush-hour-traffic.
Had to constantly tap the brake pedal to keep things pumped up. GNTTYPE flowchart confirmed it when I got home.
 
OK, here are some testing results...

Using the T/S guide from GNTTYPE.ORG, it appears that the accumulator is proven to be bad.

My fluid levels were good on the DS chambers, the large PS chamber was probably half full.

I pumped the brake pedal 10 times and tested for the light to go out (my light does not come on, but listened to the pump turn on and off). It was less than 2 seconds every time. I used a stop watch and it was between 1.7 and 1.9 seconds that the pump would shut off. The guide says to replace the accumulator. That is what I am looking to do. I am also going to replace the fluid in the resevior completely and wipe it out well.

As for the light not coming on. That concerns me. I T/S that and found the bulb socket very jacked up and replaced the socket with another from the light assembly. I still had no light of the brake bulb. I tested for power and ground and found neither there at any time. Hmmmmmm, that make me wonder why it would not work.

I did check the firewall bolt with a larger black wire and a ground strap that goes to the intake bolt at the rear DS of the motor. It is tight and the black wire goes into the harness just below the PM master cylinder assembly. I believe it is good.

As for leaks, I did notice there was a slight moisture on the pressure switch. Maybe that is causing a problem also. I am thinking I should replace it also, is that where the brake light signal comes from?

If I replace the accumulator and the pressure switch, I am thinking it os OK to replace both at the same time as they both require releasing pressure by depressing the brake pedal with key off 10+ times. Any advice on that proceedure?


Thanks in advance,
Mike
 
OK...

Where do I get these parts from?

I thought I found the accumulator and it was not the correct part for our car.


OH NO !



Mike
 
I have found the accumulator for some $135 shipped, although I found that another part number 18038506 was a replacement unit and MUCH cheaper - but I can't find it anywhere.


Thanks again,
Mike
 
Beamer said:
I have found the accumulator for some $135 shipped, although I found that another part number 18038506 was a replacement unit and MUCH cheaper - but I can't find it anywhere.


Thanks again,
Mike
Click to expand...

Where are you getting it for $135.00? Can you post a link? Yes, this is what you need based on how fast the motor fills the accumulator. This is proof that a significant amount of gas on the other side of the bladder in the ball has leaked out.
 
Ttype6 said:
Where are you getting it for $135.00? Can you post a link? Yes, this is what you need based on how fast the motor fills the accumulator. This is proof that a significant amount of gas on the other side of the bladder in the ball has leaked out.
Click to expand...

How about here:

18038507 - GM ACCUMULAT


It sounds like this is a pretty good deal. I am really questioning whether to keep the powermaster or just switch over to vacuum. I really like the cleaner origonal look over the big bulky vacuum booster. I really don't know.



Mike
 
Beamer said:
How about here:

18038507 - GM ACCUMULAT





Mike
Click to expand...

I don't know about that one. Based on the fact that there is absolutely NO information on that site pertaining to what it fits, or even what it looks like, I'd stay away. Kirban or Highway Stars both sell what you need and rest assured you'll get the CORRECT part.
 
TurboDave said:
I don't know about that one. Based on the fact that there is absolutely NO information on that site pertaining to what it fits, or even what it looks like, I'd stay away. Kirban or Highway Stars both sell what you need and rest assured you'll get the CORRECT part.
Click to expand...

You make sense, but this was the part number from GM when they were produced.

I wonder if these are old parts that have been sitting for a long time. If so, I am thinking that they would be something to stay away from. I may call the vendor to inquire about them just for giggles. thanks for your thoughts Dave !


Mike
 
I have a clicking powerbooster. I have noticed that ground wire from the firewall on my car is not connected. I can not find where is connects to the braking system? Any Ideas? I thought it was a ground wire from an alarm but looks like a factory wire and connector on end. Just don't know where it goes.
 
OK, I received my accumulator this evening and installed it. Took around 5 to 6 seconds to cycle and tested good. I then shut the motor off and pumped the brakes until the pressure let go and let it pressurize again and it pressurized great again in 5 to 6 seconds. I would get several depressions before the pump would cycle on again, like 2 to 3. It seems to be good to go now. I will get a large bottle of fluid and a new turkey baster to drain the reservior to flush the system as well as I can.

I did notice that there had been brake fluid apparently leaking out at the ball and was blistering the paint all around the ball where it screws into the M/C. There was even blistering paint all to the bottom of the accumulator and had rust flaking from the metal.

How much fluid should be in the motor side of the reservior? There is not a min/max line that I could see tonight.


Thanks, Mike
 
The motor side fill it about half way up put the lid on dont clamp it on yet. Turn the car on and watch it suck the brake fluid down make sure the resivior does not empty. Once the fluid is down fill it about an inch from the Bottom. This side does not get filled cause the fluid that was sucked down will need to come back into the resivior and you will need the room. So only about an Inch. Do this every two years and your brakes should last a bit longer. If you drive your car alot change the fluid once a year.
 
TRICKSIXPA said:
The motor side fill it about half way up put the lid on dont clamp it on yet. Turn the car on and watch it suck the brake fluid down make sure the resivior does not empty. Once the fluid is down fill it about an inch from the Bottom. This side does not get filled cause the fluid that was sucked down will need to come back into the resivior and you will need the room. So only about an Inch. Do this every two years and your brakes should last a bit longer. If you drive your car alot change the fluid once a year.
Click to expand...

Perfectt. Just what I wanted to know.


Thanks,
Mike
 
Beamer, where did you buy the accumulater ball? GM parts giant says they have it...but I'd be willing to bet they don't. That place is awful!
 
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