The PowerMaster Bleeding Procedure

Disclaimer:

I am aiming to help those who wish to ‘do it themselves’. I am not a professional auto mechanic, nor do I claim to be. I have been repairing automobiles as a hobby for about 20 years now and have performed many different operations and techniques with brake systems. The below procedure is what I have discovered to be the best method for achieving optimum braking operation from the PowerMaster (P/M) and/or any brake system.

There are other manuals and descriptions that explain brake-bleeding, repair and maintenance procedures. I have purchased, read and tried many of them. Many of the techniques explained here will also work on a vacuum system. Please do not consider this as ‘the only way to do it’. I am always open to new and interesting ideas.

I reserve the right to edit this procedure at my will and desire. Every so often I learn something new about brakes that may have relevance to this procedure. Please forgive any incompleteness you may notice here. This procedure is ongoing research and I have not taken photos yet for better explanation.

Forward:

Theory:

All of the techniques described here take place with the P/M installed on the car. If any repairs to the P/M or the brake system in general are needed, perform those repairs first. If the P/M has been replaced as a complete or rebuilt unit, you will need to perform the Bench Bleeding procedure before connecting the brake lines that go to the wheels.

The P/M must be well maintained in order to function correctly over the course of time. Clean fluid is a must. If your fluid is dark, black or cloudy, it should be replaced. A regular flushing/bleeding can be done with the correct tools in a reasonable amount of time. My own personal preference for fluid is DOT4. I have been using it for many years now and just all around seems to work better than 3. It has less resistance to fading, and darkening and doesn’t seem to absorb moisture near as much.

Brake systems work on applied pressure and must be completely free of air to function as intended. Brake fluid is like hydraulic fluid as it is not compressible. If you have the ’soft pedal’ feeling when you hit the brakes, you most likely have air. The system must be free of any and all leaks while these procedures are performed. A leak will let the fluid out and the air in, neither of which is wanted.


The P/M has 2 sides to it. Therefore it has a divided reservoir (bowl). They are:
1 - The high pressure side with the pump & motor, the accumulator (acc), the pressure switch and the passenger side (p/s) of the bowl; and
2 - The standard side, which is your typical master cylinder and the drivers side (d/s) of the bowl. Even though they are part of the same unit and work together, they can be considered two separate parts and should be bled individually.


Getting Started:
Assemble the needed items.
1 - You will need an ample amount of brake fluid;
2 - Flair wrenches and/or sockets to loosen the wheel cylinder bleeder screws and/or brake line nuts;
3 - A catch container so as not to spill the brake fluid;
4 - Some clear plastic/vinyl tubing appropriately sized to fit snugly over the tip of the wheel bleeder screws;
5 - A turkey baster or a 60ml syringe dedicated to automotive use;
6 - Special threaded fittings with small clear plastic/vinyl hoses will be needed for bench bleeding. These fittings can be found in the ‘Help’ section of your local parts store, the clear plastic/vinyl hoses can be found at your local ‘chain’ type hardware store;
7 - You will also need lint free rags for cleaning out the bowl if old fluid is present, but standard shop rags for normal use.
<insert multiple pics>

Bleeding the PowerMaster Accumulator:

Note: Check the fluid level in the bowl before you begin. If the p/s of the bowl is full of fluid, use the baster and the catch container to remove about half of the fluid before you depressurize (pump down) the acc. It is over full and will spew brake fluid everywhere when you pump down. Acc bleeding should also be performed whenever it is replaced for general maintenance.

Step 1 – Pump down the accumulator. 10 pedal pumps (min) with the ignition key off.

Typically the pedal will get quite firm when you get the pressure down. Brake fluid should be coming into the p/s of the bowl when the brake pedal is being released. Frothy fluid may develop as the p/s of the bowl fills with fluid from the acc. The fluid is saturated with air (microbubbles). It should clear up in a few minutes. If it doesn’t, remove the fluid from the bowl and replace it with fresh fluid. If the fluid returning into the bowl is dark or cloudy, replace it with fresh fluid. Wipe the inside of the bowl clean with the lint free rags as needed to remove old fluid or contaminants.

Step 2 – Pump up (re-pressurize) the Accumulator. Be sure the p/s of the bowl is full with good fluid and turn on the ignition key. Do not start the engine.

The pump should begin running and the fluid level should begin to drop in the passenger side of the bowl. Do not allow the p/s of the bowl to empty. Observe the rear port of the p/s bowl when pumping up. No fluid should be returning into the bowl through the rear port during this part of the process. Returning fluid indicates an internal leak. An appropriate sized piece of that clear tubing can also be used to aid in seeing returning fluid. <insert pic>

The 20-second rule: Do not allow the motor to run more than 20 seconds at any time.

A properly functioning P/M should not run more than about 7 seconds before it shuts off automatically to pump up the acc. If the key needs to be turned off due to this rule, wait a few minutes for the pump/motor too cool down before turning the key back on. Pumping down may help if it is a brand new acc. There may be air in it and it needs to come out. If the motor still will not shut off in less than 20 seconds, the diagnostic procedure may help to determine the problem.

Accumulator bleeding should be repeated until no air (frothy fluid, microbubbles) is present on pump down.

“Bench Bleeding” the Master Cylinder:

Note: This procedure is also suitable for vacuum systems as well.
On a P/M, the acc MUST be pumped down for Bench Bleeding.

Step 1 - Be sure there is clean fluid in the d/s of the bowl. Remove and replace the fluid if necessary. Use the lint free rags to clean the bowl if needed.

Step 2 - Remove the two flare nuts that hold the brake lines into the P/M cylinder using a flare wrench if they are not already disconnected. Brake fluid may begin to leak out of these two ‘ports’. Connect the two fittings with hoses into these ports and use the hoses to route the fluid back into the d/s of the bowl.
<insert pic>

Step 3 - With the key off, have an assistant depress the brake pedal to force fluid out of the ports, through the fittings/hoses and back into the d/s of the bowl. Air bubbles should appear in the hoses and may come out of the suction ports in the bottom of the bowl. As the air works into the bowl, try not to allow the air to be sucked into the hose when the assistant is releasing the pedal. It may be of help to depress/release the pedal slowly and momentarily hold the pedal fully depressed if a lot of air is present. This will give the air a chance to come to the top of the fluid in the bowl. Work the air out in this method until there is no air present during any part of the pedal movement.

Once all the air is removed, the fittings with hoses can be removed and the brake lines reconnected. Some fluid will leak out of the ports. Clean up as appropriate. The wheel cylinders and calipers must now be bled to complete this process. There is air in the lines.

Wheel Cylinder & Caliper Bleeding:

I am only aware of 3 methods for this. They are Gravity, Pressure and Vacuum.

Gravity bleeding consists of loosening the bleeder screws at the wheels and allowing the fluid to naturally flow downhill and take the air out with it. Personally, I have never obtained good results with it. If you prefer this method, that is your choice.


Pressure bleeding (sometime called pump bleeding) procedures can be found at the bottom of this page: Brake Bleeding, Rear Cylinders, and Linelock Install
This method is quite typical of what most people are used to doing. However, I recommend that pump bleeding be done with the ignition key off. It can prolong the life of the P/M motor and possibly a newly installed accumulator as they don’t need to be in use to get the desired results. The pedal will most likely be quite firm when pump bleeding with the key off but it can be done. I also make this recommendation as there is a chance that the high-pressure system can introduce some air into the system unintentionally.


Vacuum bleeding is my preferred method. It is easy, simple, highly effective and does not require the need for pumping the pedal. It will also rid your brake system of small contaminants that cannot be removed with pump bleeding. Of course, a special vacuum pump is needed. They can be obtained from some parts stores and also from on line catalogs. You do not need to depress the plunger on the proportioning valve to do vacuum bleeding.
<insert pic of pump>

Step 1 - With the vacuum method, you first need to wrap the threads of the bleeder screw on each wheel with Teflon (PTFE) tape. This helps to keep the vacuum from pulling in air through the bleeder threads and instead pulling brake fluid through the lines. Remove each bleeder from the wheel, wrap once or twice with tape and reinstall finger tight until it bottoms out. Loosen ¼ turn or so and connect the clear tubing right to the end of the bleeder screw. This can be done as you get to each wheel.
<insert pic>

Step 2 - Bleed the wheels in the same order as pressure bleeding. For each wheel, connect the clear tubing from the bleeder screw to the vacuum pump and raise the suction level to about 20”.
<insert pic>

Allow the fluid to flow until clear (transparent gold) fluid appears w/in the hose. Tiny air bubbles may appear w/in the clear hose. This can be considered ‘normal’ as the Teflon tape does not create the perfect seal. Large air bubbles are what you are looking to try and remove. DO NOT allow the d/s of the bowl to run empty during this process. Your assistant may be helpful to keep this from happening.
<insert pic>

NOTE: 20” of vacuum on the system may be too much for some seals – especially on rear wheel cylinders. If you find that there are large gulps of air (much larger than you would suspect) you may be sucking air in past the seals on the cylinders. Drop you vacuum down and see if you get acceptable results.

Testing:

Once all bleeding procedures are complete, pump up the acc and test for standard (typical) operation. A driveway test is recommended before taking your Turbo Regal on the road. If the desired results are not as expected, either air is still present or another problem exists w/in the brake system.

On an alternate note, if you TR seems to take a hard ‘nose dive’ when you apply the brakes, your rear drums (for those that still have them) may be out of adjustment. That is another procedure.

Do you have any preferance on the vacum style bleeder?

Nice write-up Zeus. This should be a sticky.

I actually just found my old plastic one the other day. It doesn't have a guage, but it did work. My gauge pump (I believe) is brass and works just great. Bought it from CarQuest. The plastic one I got from EastWood.

I don't think the materials really matter, but I would think the metal one would hold up longer. Best to have the gauge model at least. With it, you can have a good reference to how much vacuum you are putting on the system. You can also test other vaccum operating items on your vehicle with it. Cruise module, block off switches, egr, etc.

Thank you. It did take some time to make sure I covered everything.

This procedure rocks. It's comprehensive, well thought out, and puts the Buick shop manual to shame. After a nightmare time of having a shop screw up my PM by treating it like a vac system, I hunted down the best bleeding process (this one!), and the best mechanic I could find. Zeus, your procedure was great, and should be celebrated with a *sticky* on this site. Thanks also for taking the time to answer all my questions. Take care bud. Make this a sticky!

just replaced my pm unit.....could not have done it without Zeus.....he really took the time to walk me through it and has complete understanding relating to powermaster....thanks again

I need to learn all i can about the hb i have a t-type with it from a 83 looks alot different then most

Hydroboost is simple.
Treat the m/c and the calipers/slave cylinders like any other vacuum system.
Only difference is that your booster works off the power steering pump and not the engine vacuum. The big round boosters you are used to seeing are nothing more than a large vacuum diaphragms. Your booster is all it needs to be to give you power from the steering system.
Keep it in good shape with good fluid and you should be good to go.
If the booster needs to be replaced, get a rebuild or a kit.
They should be readily available.
GM also used them on Astro vans.

If you need info an putting it back together, you would need to contact someone with an early year TR.
Lots of help around here.

I was searching around and found a great site it was a conversion from vacuum to hydro and it is full info Hydroboost Brake Conversion - 1

Bleeding tip #1...

On a fresh install, bleed (cycle) the accumulator before doing your typical bench bleeding. As you will be pumping the pedal to do this, go ahead and hook up your bench bleeding lines and fill both sides of the bowl with fluid. When you pump down the acc, you will be bench bleeding at the same time.

I cannot strees enough that ALL THE AIR MUST BE REMOVED for the acc to function properly. Use a light to look into the fluid to see if there are any tiny air bubbles escaping from the return port (rear port). As the air is removed, the pump up time will be reduced.

Bleeding tip #2...

If you happen to be installing a rebuild unit from Kirbans (the Cardone unit) try your best to flush out the left over fluid that is there. I believe it is rubbing alcohol - it doesn't evaporate. I have seen this in 2 of thier units. I am no chemist, but I don't think it should be in there with brake fluid.

Flush it with denatured alcohol as best as possible without disassembling it. The denatured alcohol will evaporate clean away, and will remove the rubbing alcohol as best as you can flush it. Carefully blow dry with compressed air if possible.

I don't know if the units GBodyParts or anyone else sells, are the same.

Hard copies....

If anyone is interested, I do have this in a plain-jane hard copy so you don't have all the Vbulliten board stuff print out with this.

Feel free to ask.

Z

A note on Bleeding (cycling) the accumulator...

- Over the course of time and use, it is possible for air to get back into the acc. The only explanation I can think of is the pump can churn up the fluid.

So once in a while, give the acc a wake up call -> Cycle it.
Aka - pump it down and then back up a couple of times as I have explained above. If you get frothy fluid out of it, it's a good thing. It's air and needs to be removed.

I have begun making this a practice when I change my oil.
It doesn't hurt a thing, costs no money, uses no tools, and you can time the acc pumping up to help determine it's health.

- Also, 7 seconds for pump up what should be considered the "perfect" time. When mine was fresh, 7 seconds was not a problem. Mine actually runs about 12-13 seconds these days and I have not experienced any problems to date. I have checked this time with both my 8yr old 2nd gen acc that was new at rebuild time, and my new 3rd gen acc that I got a short time ago.

I have also seen these kind of pump up times on the Kirbans units that he gives the lifetime warranty on.

Z