Hard pedal, no brakes, brake light on...

[dz28]

Gravity bleed as the GM service manual suggests... I agree, it sounds like air in the system. I may try to suction bleed the master cylinder but may just say the heck with it and find someone who knows what they are doing. I obviously do not and I have always had a rule when playing with cars, brakes are something you don't fool too much with. The result of doing things wrong is typically not pleasant...

 

[zeus87gn]

Gravity bleeding doesn't work. JMHO.
Never tried suction bleeding.
Bench bleeding works the best to me and doesn't use a gallon of fluid.

Experienced help is a wonderful thing.
I am getting some for the flooring in my home.
I don't want to waste $3500 of the matls I just bought.

 

[dz28]

I may try to bench bleed process to see what happens. It's hard to tell when suction bleeding at each corner if any air is passing through. Just frustrating when the car is down, work gets in the way, and the car just sits when we do have a rare day when it is nice up north... thanks for the help and I'll keep the thread going til the old girl is running again...

 

[zeus87gn]

Bench bleeding would be my recommendation.
P/M don't like even the tinyest bubble of air.

If you use some clear tubing like I have shown in my bleeding thread, you can see the air right off. I got some at my local Lowes. Got the fittings from HELP! at the 'Zoo. Last one I did I had to bleed until I was dead (so it seemed) The air was just everywhere. I cycled the acc like 15 times in the process. It was a fresh reman from Kirbans. By the time I was done, it literally threw my pal into the windshield. He still gives me he!! about that but he didn't have his seatbelt on.

Take your time with the pedal pushing.
If you go too fast it will churn up the air that is in there and make matters worse.
If you watch the fluid flow while you helper pushes the pedal, you can tell them to slow down if the air is going by too fast for you to see it.

 

[BW Jones]

appreciate the responses.. what's the connection between the accumulator and the AC system?

many thanks to zeus for his valuable input regarding the powermaster system.
as he has stated, there's no connection between the accumulator and the A/C system. there is however a connection between the powermaster's relay and the A/C system according to the service manual. they are on the same electrical circuit (protected by the same 25A fuse). therefore, if the A/C fuse opens (blows), the powermaster's relay will not be energized.

bw jones

 

[dz28]

Thanks, and yes, Zeus has helped a great deal... I haven't touched the car in a couple of weeks due to business travel. Hoping to get under the hood again this week and go through a manual process of bleeding the PM, then reaching out to all four corners, and hoping for a positive result.

 

[youngstr]

Guess I get to join the infamous Hard Pedal Club

Wow, glad I found this thread, first time dealing with a power master, lots of useful info here. I use my T-type as a daily driver so it really freaked me out when I started the car after getting lunch at Mc'ds today only to find a rock hard pedal, almost no brakes and solid brake light on the dash. under the hood, brake resevior full to the top, pump it down? heck the pedal barely moves! Anyway, I get to tear it down and do all the tests I found here till i find the culprit, my spidersense is betting on the pump to be spent as it appears from the resevior that the acc is probably pumped down and the pump is not doing squat to refill it. We'll see. Only one thing to question about gm engineers, something as important as brakes you would think that they would have gave it its own independant circuit.....I can't beleive you can blow fuses that could cause an accident, but hey, I guess welcome to powermaster ...right?

 

[BW Jones]

check your 30A brake fuse in the fuseblock. read the posts by zeus87gn and the links he has provided ........ it's very valuable info for diagnosing powermaster problems. post the results of your testing and any questions you have. the help provided by the members here is outstanding.

bw jones

 

[zeus87gn]

Only one thing to question about gm engineers, something as important as brakes you would think that they would have gave it its own independant circuit.....I can't beleive you can blow fuses that could cause an accident.......

Don't get me started about GM engineers.
If I ever meet some of them....

Better to blow a fuse and have to go 'Fred Flinstone' on the brakes than to have an over current condition and start a fire with overheated wire insulation.

Take your pick.

 

[aminga]

Don't get me started about GM engineers.
If I ever meet some of them....

When Automotive engineers get sent to hell they spend eternity working on the things they designed.


Try changing the tranny fluid on a silverado 4WD.

 

[youngstr]

some testing done

I pulled everyfuse, checked every one just to be thorough, all fuses are ok. When I discovered that I no long have a volt meter, had to jet down to the walmart, grabbed a cheap little analog, have to take it back later cause it says made in china so naturally the ac side works fine, but dc side is dead, even used my battery to ground to confirm, so i'll return that later for a better one, I did notice that when I have the ignition on and leave the plug on the motor, but pull the plug for the pressure switch, upon re installing the pressure switch I hear a click so even before I get an ohm meter that works I'm suspecting I have juice to the motor, the switch would seem to be working... but I know, I still have to test everything cause that switch could be the cause if its closed all the time.....so will get back to everyone once I get that done later tonight. Guess I'll have to break out the beater car for work tomorrow.

 

[youngstr]

Ok, after doing all the electrical tests, the motor does not pass. I put current across the one circuit that was supposed to be open. so its toast it must have run it self to death.

Now I have the big decision to make, do I pay 175-200 for a new pump, or do I just get the vacume conversion kit for about the same amount of scratch and not deal with anymore PM problems.

 

[zeus87gn]

Ok, after doing all the electrical tests, the motor does not pass. I put current across the one circuit that was supposed to be open. so its toast it must have run it self to death.

Are you sure you have the right terminals?
http://www.gnttype.org/techarea/images/PwrMstr.gif

Be sure you are thinking correctly.
The motor terminals, C & A, won't allow current to pass through the motor (making it run) unless the coil is energized across B & C.
If you tested it with the volt meter, you wouldn't get anything anyway.
Volt meters (even expensive ones) can't drive a motor load.
If you test for resistance, you would get no reading as the coil is not energized to complete the circuit - guessin you don't have the motor plugged in.

Now I have the big decision to make, do I pay 175-200 for a new pump, or do I just get the vacume conversion kit for about the same amount of scratch and not deal with anymore PM problems.

That dicision is yours to make.
If you do decide to be a convert, do yourself a favor and make sure you install a vacuum reserve canister.

 

[dz28]

Zeus, do you know the size of the fittings on the side of the MC? This weekend I hope to spend more time digging and learning the mysterious ways of the PM system. I'm still thinking my problem is up front and not underneath. I will of course bleed through the four corners but think my problem is either air in the ACC or MC. I am going to allocate about a half day to the bleeding effort and find a way to get this thing right... your help is sincerely appreciated but not just me but several of the folks in this thread...

 

[zeus87gn]

The technical sizes of the threads?
I don't have that info in front of me here.
I'll have to check my manual at home and see if it's there.
I'd guess 3/8" and 1/2", but I'm probably wrong.
They are most likely Metric (knowing my luck), 10 & 12mm.
I know they are not tapered threads.
I'll see if the fittings have the sizes on them.

If you're looking for the fittings to bench bleed on the vehicle, go to the HELP section at your local parts store and get the assortment. The right fittings are in there. They are in the picture I posted in my bleeding thread (link in sig).

 

[dz28]

Yep, going to bench bleed the MC and saw the pic depicting the fitting and looping the fluid back into the res. I want to have all my stuff ready so once I go underhood I can stay there until I fix the ole girl. If the sizes are on there that's great, if not I'll just buy what they have and hope I have everything I need. Thanks again for the help...

 

[zeus87gn]

You mean this pic?

 

[dz28]

that's the one

 

[zeus87gn]

HELP section fittings and white plastic tube holder.
All comes in the pack.
Clear plastic tubing from Lowes. Don't remember the size, but it one of the smalles ones they have.

Pump with the key off and the acc pumped down.
Wait a moment or two with the pedal down to allow the bubbles to float away from the ends of the tube. Release pedal slowly. Press down with a little more authority than the release. Take your time and don't settle for anything less than perfection. NO BUBBLES of any size.

Edit: You're welcome for the help!

 

[youngstr]

You're right, I tested the motor backwards, I went a to d from left to right, diagram goes right to left. I'll retest the motor tonight, and the harness, but the test I did on the switch all circuits showed continuity, which is what the guide says they should be, so I guess I can rule out the switch at this point.

Still, I don't like the Idea that I could suddenly have very little brakes, the PM when working does provide a ton of braking power and If my car was a show car I'd worry more about keeping it original, but its a daily driver, I bought it to enjoy it as often as possible, to modify it, and my kids like to ride in my car, if that would have happened in heavy traffic on a highway with my kids in the car, no.... I can't deal with the thought of that, . So with all that considered, I think I"m gonna make the change to vacuum boosted brakes. Don't get me wrong, I like my regal, I just think for now going vacuum is the safer option for me and mine. that res vac tank u mentioned, thats just to extend the time I have brakes in the event my engine dies at high speed? or is there an issue of the vacuum thinning out when you put the car into boost?