Powermaster brakes diagnostic information

TurboBuRick

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The following information is copied from the service manual.


POWERMASTER BRAKES DIAGNOSTIC INFORMATION #93-5-107 - (03/31/1993)
SUBJECT: POWERMASTER BRAKES (DIAGNOSTIC INFORMATION/INSTALL NEW KIT)

VEHICLES AFFECTED: 1986 "B" MODEL (WAGONS) AND 1985-87 "G" MODEL (TURBO CARS)

THIS BULLETIN SUPERSEDES AND REPLACES CORPORATE BULLETIN REFERENCE NUMBER 035002.** THIS BULLETIN IS BEING REVISED TO INCLUDE MORE DIAGNOSTICS AND INTRODUCES NEW REPAIR KITS FOR REBUILDING THE POWERMASTER UNIT.

This bulletin provides brake diagnostic information that will help to correctly diagnose and resolve concerns with the Powermaster Brake System on 1986 "B" Station Wagons and Buick "G" 1985-87 Regal Turbo vehicles.

If, after following this procedure a technician still has a question, Delco Chassis Division has set up an 800 number for additional assistance. Call: 1-800-523-0203

CONDITION:

--------- Some owners of 1986 "B" station wagons or 1985-87 Buick Regal Turbo vehicles equipped with the Powermaster Brake System may experience either "harder pedal feel" or "increased pedal travel". The red brake warning light may also be illuminated. This should normally coincide with the hard pedal feel or warn of impending hard pedal if a concern is not resolved. It may also momentarily or continuously illuminate in conjunction with the increase pedal travel problem.

CAUSE:

----- A. "Harder Pedal Feel" symptoms can be diagnosed from this bulletin. There are four likely causes to be aware of:

1. ACCUMULATOR WITH LOW GAS CHARGE: Symptoms - Pedal is momentarily hard and/or brake warning light flickers on normal to fast brake applies.

2. PRESSURE SWITCH FAILURE: Symptoms - Pedal remains hard on all applies and pump fails to run.

3. PUMP FAILURE: Symptoms - Pedal remains hard on all applies and pump fails to run or may run continuously (with or without brake application).

4. INTERNAL OR EXTERNAL LEAKAGE: Symptoms - Pedal remains hard on most or all applies. Brake fluid may be present on outside or rear of unit. Pump runs continuously or cycles frequently (with or without brake application).

B. "INCREASED PEDAL TRAVEL" symptoms can be diagnosed from this bulletin. If this symptom is recognized in conjunction with "HARDER PEDAL FEEL", follow the diagnostic procedures for "harder pedal feel".

NOTE: Replacement of the complete Powermaster assembly is not required to correct most customer concerns. Part kits are available that will resolve most concerns with this system, and eliminate unnecessary replacement of the complete Powermaster assembly.

See Figures 1 and 2 for component identification.

HARDER PEDAL FEEL DIAGNOSTICS PROCEDURE

PROCEDURE/TEST RESULT CORRECTIVE ACTION -------------- ------ ----------------- Fluid Level/External Leakage:

Make 10 brake applies with Below minimum mark Follow Corrective Action ignition "off". Step #1. Check fluid level of pump reservoir (Fig. 2).

- OR - Above gage marks Reservoir overfilled Remove excess fluid Continue diagnostic

- OR - Within normal level No action required gage marks Continue diagnostics

WARNING
Light Operation:

Check red brake warning Light does not No action required light with normal braking illuminate Continue diagnostics (Ignition "On").

- OR - Light comes on and See accumulator operation goes off diagnostics

- OR - Light comes on and See booster operation may stay on diagnostics.

Make a series of rapid Light comes on and No action required. brake applies (one apply goes off Normal operation. per second). Continue diagnostics

Accumulator Operation:

Make 10 brake applies with 0-1 second Replace accumulator P/N ignition "off" 18014978 or 18018722 Turn ignition "on". per instructions on Check time from motor "start" installation. to red light off.

- OR - 2-7 seconds No action required. Continue diagnostics.

- OR - 8 seconds or greater Follow Corrective Action Step #2.

Booster Motor Operation:

Turn ignition on and make Motor does not run, Follow Corrective Action normal brake applies no power assist, Step #3. red warning light illuminates.

- OR - Motor does not shut Follow Corrective Action off within 15 Step #4. seconds.

Internal Leakage:

Wait for pump to shut off Pump cycle without Follow Corrective Action after normal run cycle a brake application Step #2.B Keep ignition "on" being made. Wait for five minutes.

INCREASED PEDAL TRAVEL DIAGNOSTICS PROCEDURE

(ALL MODELS)

Inspect for external leaks Leakage observed Repair leak or replace between master cylinder leaking part. Add fluid outlets and wheel brakes to master cylinder reservoir per Figure 2.

- OR - No leakage observed. Proceed to next step below.

(1986 STATION WAGONS ONLY)

Bleed left front caliper only. Pedal Travel Replace combination significantly valve with brass valve improves.* (P/N 25509419) and re- bleed total system

- OR - Pedal travel is Bleed total system and still excessive* check drum brake ad- justment.

Bleed entire brake system Pedal travel is Repair Powermaster unit and check drum brake still excessive* with Seal Repair Kit adjustment 18020067

(1985 - 1987 BUICK REGAL TURBO ONLY)

Bleed entire brake system Pedal travel is Repair Powermaster unit and check drum brake still excessive* with Seal Repair Kit adjustment. 18020067.

* Note: To properly evaluate pedal travel, apply brakes with vehicle parked, ignition off, and without power assist (de-pressurize system with ten brake applies). Pedal travel on the vehicles should be maximum of 57 mm (2-1/4 inch) with normally worn brake linings when checked at 100 pound pedal force using J-28662.

CORRECTIVE ACTION STEPS

STEP #1 - LOW FLUID IN BOOSTER PUMP RESERVOIR DUE TO EXTERNAL LEAK. ------------------------------------------------------------------ A. Make ten medium to high effort brake applies with ignition off to de-pressurize the system. Check fluid level in booster pump reservoir by observing if level falls between the two gage marks located on the inside of the pump reservoir (Figure 2).




RL
 
Last edited:

Dennis GN

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Oct 15, 2012
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I have been trying to find out what is wrong with my brakes on my 1987 Buick Regal. this what i know so far the brake light is on when i turn on the ignition and stays on. when i turn on ignition the pump always runs about 2 to 3 secounds and shuts off. Brake pedal stays hard and i have almost no brakes.Also when i checked out the pressure switch there is no continuity at A on switch but i do on B and C. The switch is the new Gray unit,dont know how new it is. I noticed with the cover off of the master cylinder when i push on brake pedal fluid will shoot out of both ports close to fire wall driver side and passanger side. Need help thanks Dennis
 
Sep 28, 2013
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Shenandoah Virginia
Been having trouble with my brakes.About 2 months ago the big side of the reservior was empty.No light came on at that time and I refilled it just last week my brake light came on and when i got to work there was a pile of fluid on the ground but the resevior was still full and the pedal you have to stand on with two feet to get a slow stop.I have it at the shop and they have bleed the brakes and replaced a fuse that runs the motor and got the light off but when they pump the brakes it poors out the cap like it is not going back in.He suggested that we replace the master cyclinder and go from there as he feels the seals are bad.Was there a recall on this system?I have a blk ball, a motor and the master cyclinder wth a square resevior. If it was a recall how do I find out if the last owner took care of this?I have priced this stuff and it's really expensive like 1200.00.I called my machinac today and told him I found a recall but wasn't sure if it was on mine.
 

626gn

Well-Known Member
Feb 15, 2009
2,189
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Honolulu, Hawaii
Been having trouble with my brakes.About 2 months ago the big side of the reservior was empty.No light came on at that time and I refilled it just last week my brake light came on and when i got to work there was a pile of fluid on the ground but the resevior was still full and the pedal you have to stand on with two feet to get a slow stop.I have it at the shop and they have bleed the brakes and replaced a fuse that runs the motor and got the light off but when they pump the brakes it poors out the cap like it is not going back in.He suggested that we replace the master cyclinder and go from there as he feels the seals are bad.Was there a recall on this system?I have a blk ball, a motor and the master cyclinder wth a square resevior. If it was a recall how do I find out if the last owner took care of this?I have priced this stuff and it's really expensive like 1200.00.I called my machinac today and told him I found a recall but wasn't sure if it was on mine.
Starting a new thread and posting it in this section will get you more action.

The original Powermaster brake system is foreign to many shops due to the short period GM used this system. It can be a very problematic system especially if it has not been properly maintained (and most don't know how to properly maintain it). If originality is your thing then, yes, you could be dishing out some $$ to fix it as you have already found out. Most who start experiencing problems with this system simply replace it with a vacuum brake system. There are other options as well but a vacuum conversion is the most common. Parts can be had for around $200 - $300 if you shop around and its relatively easy to do. Do a search on "vacuum brakes" and you will get more results than you need.
 

TurboDave

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May 24, 2001
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Been having trouble with my brakes.About 2 months ago the big side of the reservior was empty.No light came on at that time and I refilled it just last week my brake light came on and when i got to work there was a pile of fluid on the ground but the resevior was still full and the pedal you have to stand on with two feet to get a slow stop.I have it at the shop and they have bleed the brakes and replaced a fuse that runs the motor and got the light off but when they pump the brakes it poors out the cap like it is not going back in.He suggested that we replace the master cyclinder and go from there as he feels the seals are bad.Was there a recall on this system?I have a blk ball, a motor and the master cyclinder wth a square resevior. If it was a recall how do I find out if the last owner took care of this?I have priced this stuff and it's really expensive like 1200.00.I called my machinac today and told him I found a recall but wasn't sure if it was on mine.

I'm not clear where the fluid is leaking from. The lid??? If so the lid is kinda hard to get placed properly. Takes a good bit of effort. The gasket MUST be properly placed on the lid prior to install. And as I said the lid is kinda hard to get properly locked down if one is not paying close attention.
 
Sep 28, 2013
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Shenandoah Virginia
It is coming out the lid.You can see whe they pump the brakes like three times it pulls from the smaller area in resevior fills the bigger side near the motor and pours out of the lid.
 

TurboDave

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First thing you gotta do is get the lid off. Turn the key on and let the PM pump pull the fluid down out of the inside (motor side) of the reservoir. When that's done the level should be fairly low, no more than 3/4" deep in the deepest part (rear). If you look in the rear corner of that side of the reservoir (inner rear corner) you'll see a two step marker. Turn the key off and SLOWLY push the pedal down so the fluid doesn't spurt over the reservoir. Do this at least 10 pushes until the pedal is very hard.
The fluid in the booster side (inner side of the reservoir) should have risen. Keep its level between the two step marker. If it's too full, take some out.

Also, the outer side of the reservoir should really be no fuller than the "step" that's on the rear of that outer reservoir.

Once all that's done you'll need to get the gasket back onto the lid, it fits a little snug. Then put the lid on the reservoir. It's hard to get properly seated. I push down good and firm at each latch until I hear it click/lock. Do that to all four latches.

Chances are that if you have/had to take it to some one to get any work done on it all, they screwed the job up. VERY VERY few mechanics have the slightest clue how to work on the PM.
Best advice I can give on working on the PM is, learn to do it yourself. It's really not all that hard to maintain. The only time I would have to take mine to someone else is to get the master cylinder rebuilt, and I would only take it to a TRUSED source!.
 
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Sep 28, 2013
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First thing you gotta do is get the lid off. Turn the key on and let the PM pump pull the fluid down out of the inside (motor side) of the reservoir. When that's done the level should be fairly low, no more than 3/4" deep in the deepest part (rear). If you look in the rear corner of that side of the reservoir (inner rear corner) you'll see a two step marker. Turn the key off and SLOWLY push the pedal down so the fluid doesn't spurt over the reservoir. Do this at least 10 pushes until the pedal is very hard.
The fluid in the booster side (inner side of the reservoir) should have risen. Keep its level between the two step marker. If it's too full, take some out.

Also, the outer side of the reservoir should really be no fuller than the "step" that's on the rear of that outer reservoir.

Once all that's done you'll need to get the gasket back onto the lid, it fits a little snug. Then put the lid on the reservoir. It's hard to get properly seated. I push down good and firm at each latch until I hear it click/lock. Do that to all four latches.

Chances are that if you have/had to take it to some one to get any work done on it all, they screwed the job up. VERY VERY few mechanics have the slightest clue how to work on the PM.
Best advice I can give on working on the PM is, learn to do it yourself. It's really not all that hard to maintain. The only time I would have to take mine to someone else is to get the master cylinder rebuilt, and I would only take it to a TRUSED source!.
 
Sep 28, 2013
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Shenandoah Virginia
So it's ok to take the lid off while pumping the brakes? Do you have to rebleed the lines?Also if you get the resevior 3/4 full in the biggest side do you put more in to get it to the fill line?I have two small areas on the fender side and one big area on the motor side of my resevior. Also what causes it to do this and will it happen often?
 

TurboDave

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So it's ok to take the lid off while pumping the brakes? Do you have to rebleed the lines?Also if you get the resevior 3/4 full in the biggest side do you put more in to get it to the fill line?I have two small areas on the fender side and one big area on the motor side of my resevior. Also what causes it to do this and will it happen often?
Yes, it's the best way to see what's going on while you're pumping the pressure down. BUT....One must be sure to push the pedal fairly slowly so the fluid doesn't spurt out over the edge. And keep an eye on the inner reservoir (engine side) to make sure it doesn't overflow while pumping down. It may be too full.
As I stated earlier you don't want either side "full". The outer side (fender side) maybe 3/4 full. But the inner side (engine side) has two levels, normal level which is where it should be after the key is turned and the pump has stopped running, and it's higher level which is where it should be after the key off, 10 pedal pumps pressure down.
If ya'll like, I'll try and get some pictures taken today to show the various levels.
 
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That would be greatly appreciated.So no bleeding after this and no refilling to the top line? My machanic is replacing the master cyclinder and he said if this doesn't work it could get expensive (1200.00). It lost fluid onetime when I parked after the light came on but the resevior was full so I added none.Just drove with hard hard brakes.
 

TurboDave

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Why are you letting a mechanic replace the master cylinder when we're not even sure there's a problem with it????? Is this mechanic able to properly diagnose a Powermaster system??? Does your mechanic have the special tool he needs to properly diagnose a Powermaster. It's a special device that screws into the top of the master cylinder to monitor pressures. Does he have it???? If not, don't let him touch your system again.
 

TurboDave

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OK, here's some pictures of different reservoir levels:

Here's an outside shot of the fender side at proper level:

DSC_0157.JPG



Here's a shot of the engine side at proper level:

DSC_0158.JPG



Here's a shot with the cover off: See the little step gauges to the rear inside of each reservoir? Look closely and you can see that the finder side in right at the top of the little two step indicator. The engine side appears way low but it's not. Remeber, this is normal for regular operation.

DSC_0159.JPG



Here's a shot of what happens to the engine side reservoir when the brake pedal is pressed until all pressure is out WITH THE KEY OFF!! Notice how foamy it looks. That can happen when the brake pedal is pressed a little too quickly on some strokes. DONT WORRY, the next picture shows the fluid cleared up after only a few moment wait.

DSC_0161.JPG



And now the most important one. This picture is the same as the one above after the air cleared. Notice where the level is on the step gauge (engine side!). After the key off brake applies to depressurize. It should never be any higher than what you see here.

And when you turn the key back on (after the air has dissipated) the level will go back down to normal as seen in the first lid off picture.

DSC_0162.JPG








ANY QUESTIONS?
 

chopped39

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Aug 30, 2004
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First off get the car away from that mechanic and have someone that knows the system diagnose it . If you need and want the the car all original then call Kirbans and buy a rebuilt power master . First off the system is very problematic even if maintained they are unpredictable . I purchased my car with 12,ooo miles on it and flushed the brakes every year. I knew the problems as I worked for chevy at the time. My car had about 33 or 36 k on it when it went out . You can feel how hard the pedal is right? Now have someone throw a u turn in front of you when your doing 40nph. If you want my advice take it off the car and put it in a box in the corner of your garage where it belongs and either go with vacuum or if money is not an issue go to hydratech and get the hydoboost set up. People on here will tell you to keep it .Thats because they never wrecked their car because of it failing. Mine never had the light go on and never had shown any problems. the hydratech is the way to go. Pm SilverBulletgn aka Benny and ask him about that system.He has the Hydratech system and it looks awesome. good luck with whatever you do.
 
Sep 28, 2013
57
2
8
51
Shenandoah Virginia
Why are you letting a mechanic replace the master cylinder when we're not even sure there's a problem with it????? Is this mechanic able to properly diagnose a Powermaster system??? Does your mechanic have the special tool he needs to properly diagnose a Powermaster. It's a special device that screws into the top of the master cylinder to monitor pressures. Does he have it???? If not, don't let him touch your system again.
I'll have to call and talk with him today on this and I will try the procedure you gave me thanks so much for you help.This really helped out.
 
Sep 28, 2013
57
2
8
51
Shenandoah Virginia
First off get the car away from that mechanic and have someone that knows the system diagnose it . If you need and want the the car all original then call Kirbans and buy a rebuilt power master . First off the system is very problematic even if maintained they are unpredictable . I purchased my car with 12,ooo miles on it and flushed the brakes every year. I knew the problems as I worked for chevy at the time. My car had about 33 or 36 k on it when it went out . You can feel how hard the pedal is right? Now have someone throw a u turn in front of you when your doing 40nph. If you want my advice take it off the car and put it in a box in the corner of your garage where it belongs and either go with vacuum or if money is not an issue go to hydratech and get the hydoboost set up. People on here will tell you to keep it .Thats because they never wrecked their car because of it failing. Mine never had the light go on and never had shown any problems. the hydratech is the way to go. Pm SilverBulletgn aka Benny and ask him about that system.He has the Hydratech system and it looks awesome. good luck with whatever you do.
I might have to go with the vaccum verison if we can't get this figured out.Or take it to my nearest Buick dealer.Thanks so much.Is there a vaccum system that is recommended?
 
Sep 28, 2013
57
2
8
51
Shenandoah Virginia
Your local Buick dealer is the LAST place that has anyone qualified to do any work on these cars! :eek:
You have been quite a bit of help for me here and I am very greatful that someone has had the problem I am having with mine.I will do this procedure and go from there.Thanks so much and I really didn't wanta deal with the dealer if this isn't a recall.
 
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