Bleeding a Powermaster for 87GN

[zeus87gn]

2tone,

Hard pedal feel is typical of a dying or dead accumulator.
You state 6-9sec pump time, is this time to pump up the acc from having the system pumped down?
Which acc do you have?
How many miles?

BTW, the Powermaster system pressure is 650-700psi (off the top of my head) and the units Kirbans sells are correct and the best deal going right now.

 

[2toneNV]

6-9 sec. is regarding the motor run time when ignition is turned on. The acc. as far as I know and can tell is the original and the car now has 98k. Do you have the Kirban's? Where else can you get it from?

 

[Hyboost]

Jeff Moore, where is the best place to get a rebuilt PM? Also, I have replaced the Pres. Switch but I get the hard pedal feel with the brake light coming on, would you say rebuilding the Master Cylinder is a good idea? I just don't want to invest alot of money in trying to fix this one and still end up in the end having to buy a rebuilt unit.

I bought a complete rebuilt unit from CARQUEST in Buffalo NY. If I remember correctly I paid under $300.00 for it, but that was 2 years ago. Very happy with the unit. Works good as new.

 

[zeus87gn]

6-9 sec. is regarding the motor run time when ignition is turned on.

Let me be sure I understand.....
You have the system pumped down (10 pedal pumps with the key off) when you turn the key on and the motor stops running by itself in 6-9sec?

If you were to let the P/M sit still after the motor stops and not touch it while leaving the key on, how long does it take before the motor starts running again? And then, how long does it run before it stops by itself?

The acc. as far as I know and can tell is the original and the car now has 98k. Do you have the Kirban's? Where else can you get it from?

Describe the acc (unless you can post a pic).
Does it have an embossed 'nut' on the outside of it with yellow imprinting around the 'nut' (2nd gen) and have "Made in Germany" somewhere on it?
Or is it smooth on the outer side with no yellow printing at all (1st gen)?

The only acc's available new now are a 3rd generation that you can only get from Kirbans or GBodyParts. I have both a 2nd and 3rd gen acc and they are as good as eachother.

 

[GNRick]

I don't mean to hijack this thread but it seems to have gone through several versions since Jeff Moore originally started it. My powermaster pump is running for a few seconds on almost every push of the brake pedal. It isn't very old and has maybe 4000 miles on it. It came from Autozone and I can send it back for a replacement. A reliable source told me to check for dirt in the brake line that connects to the master cylinder, under the accumulator. I think he said there is a little filter in there that might need to be cleaned. Just wanted another opinion. Thanks.

 

[zeus87gn]

There is a check valve in there that can get stuck, but I doubt that's your problem.

As it's still a young unit, try cycling the acc and see if there is air in it.
If the fluid comes out frothy when you pump down, cycle it over again until you get clear fluid on pump down..

If that doesn't work, give it the diagnostic tests.

Let me know what you find.

 

[Jeff Moore]

My opinion..I'm in Ohio..your in Illinois...It sounds like an accum..!!
How long have you had the replacement unit?? even though it's got 4000m..
Time effects the Accum and its ability to maintain pressure> Autozone
probably didn't replace the accum ..at time of rebuild..because it checked ok.. Meaning you did not get a new accum with your rebuilt..unit.
My feelings...since you have already learned how to remove/install a PM ..I would take it back..for exchange..and elliminate ALL possibilities...!!

 

[GNRick]

My opinion..I'm in Ohio..your in Illinois...It sounds like an accum..!!
How long have you had the replacement unit?? even though it's got 4000m..
Time effects the Accum and its ability to maintain pressure> Autozone
probably didn't replace the accum ..at time of rebuild..because it checked ok.. Meaning you did not get a new accum with your rebuilt..unit.
My feelings...since you have already learned how to remove/install a PM ..I would take it back..for exchange..and elliminate ALL possibilities...!!

I bought an 86 GN last April with under 25k miles on it. Brake light was on, but that didn't scare me. I used it to negotiate the price. It came from Ohio, with original 21 year old tires. I had to trailer it home anyways. A new accumulator cured it. So you are correct, accumulators don't like time. As for my current problem, this car has 175,000 miles and I'm on powermaster #3 I think. I was ready to remove it and take it back when I was told to investigate the check valve. That is easier than removing the entire unit. Actually, the accumulator is the newest version (#3?) so Cardone did replace it. It is the same version that Kirban currently sells.

 

[2toneNV]

Zeus, it is the smooth acc., no nut on the outside. I am not sure how long it takes for the motor to start running after I turn the car off and leave the ignition on, I will find out tonight. Anything other things to look for?

 

[POWERBRAKEBOB]

Hydroboost Vs Vacuum Vs Powermaster

We (Power Brake Service) can rebuild those Powermasters, and have been doing it since they were new. We also have available NEW electric motor/pumps. We have rebuilt P/M's, can, and have done, the vacuum boosters and vacuum pumps, or, our favorite for a trouble-free brake system is the Hydroboost conversion. The hydrobost uses the same pedal as the powermaster, and saves that labor.

 

[zeus87gn]

I bought an 86 GN last April with under 25k miles on it. Brake light was on, but that didn't scare me. I used it to negotiate the price. It came from Ohio, with original 21 year old tires. I had to trailer it home anyways. A new accumulator cured it. So you are correct, accumulators don't like time. As for my current problem, this car has 175,000 miles and I'm on powermaster #3 I think. I was ready to remove it and take it back when I was told to investigate the check valve. That is easier than removing the entire unit. Actually, the accumulator is the newest version (#3?) so Cardone did replace it. It is the same version that Kirban currently sells.

Rick,
Acc don't like time sitting on a shelf.
Once they are put into service, you have to treat them properly.
The 3rd generation acc haven't been around long enough to have problems.

I'll bet you my gold dollar that your acc has air in it.
Cycle it. You'll be amazed how easy it is.
No wrench turning involved, just key turning.
See the procedure in my sig.
Ask questions if you need to.

Sorry the response is late,
Z

 

[zeus87gn]

Zeus, it is the smooth acc., no nut on the outside. I am not sure how long it takes for the motor to start running after I turn the car off and leave the ignition on, I will find out tonight. Anything other things to look for?

2tone,
What you are actually doing is the diagnostic tests.
They are explained here:
Brake System

You are trying to determine pump up time and self cycle time.
The pump up time tells you what's happening in the boosted (powered) side of the P/M.
The self cycle time tells you the health of your internal seals.

As I am late in getting back to you, did you find out anything?

Oh, from your description of the acc it's either the 1st or 3red gen acc.
If it's the 1st, it's most likely bad. If it's the 3rd, something else is wrong

Z

 

[2toneNV]

zeus, I do have the acc. with the yellow label and the nut on the outside! Looking to get a new acc.

 

[zeus87gn]

Ok, let me know if you need anything further.
PM or email if you need to.

 

[GNRick]

Rick,
Acc don't like time sitting on a shelf.
Once they are put into service, you have to treat them properly.
The 3rd generation acc haven't been around long enough to have problems.

I'll bet you my gold dollar that your acc has air in it.
Cycle it. You'll be amazed how easy it is.
No wrench turning involved, just key turning.
See the procedure in my sig.
Ask questions if you need to.

Sorry the response is late,
Z

I cycled the powermaster 4 times. An air bubble came out the first two times. Second two times was fine. Pump still runs on every second push of the brake pedal. My mechanic noticed a brake fluid leak a few months ago and replaced the brake cylinders. Do you think there is air in the lines? Thanks for your help.

 

[zeus87gn]

I cycled the powermaster 4 times. An air bubble came out the first two times. Second two times was fine. Pump still runs on every second push of the brake pedal. My mechanic noticed a brake fluid leak a few months ago and replaced the brake cylinders. Do you think there is air in the lines? Thanks for your help.

Told you it had air in it.

Ok, the pump running every other push of the pedal may/may not be a problem. It has to run every so often to keep up the pressure. If it only runs for a moment or two to keep it up, it's shouldn't be a big deal.

->> The important part is how long does it take the motor to pump the acc after you have pumped it down? And, what is the self cycle time?

FYI - Air in the lines has nothing to do with the high pressure side of the P/M. You will feel a spongy pedal (like you would normally expect) when you are holding the brakes if you had this problem.