POWERMASTER
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Pix by Steven Fergus
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Just want to clear up a couple of comments on the Powermaster brake booster. It is not the same system as the GM Hydraboost. The Powermaster is a self-contained unit and it's pump is operated by a built-in electric motor while the Hydraboost gets is pressure from the power steering pump.

Also, there are not 10 applications in a Powermaster with no electricity to the pump. There will be three or four, which is still good. The 10 pumps comes from the GM instruction to press the pedal 10 times to ensure all pressure it gone before working on the unit.

 The weakness in the Powermaster is an internal switch the operates the motor and I strongly suggest to anyone who gets one to add an good reliable external switch such as the RY11 and solder closed the internal switch.

Having said all that, I have Powermaster complete with adapter and wiring for sale and an additional new accumulator. I have just installed four rear discs and had to go to the larger-pistoned master cylinder.
Al Hamilton
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Here are some pictures of the Install - Larry

http://www.gmcmhphotos.com/photos/showgallery.php?cat=3399

ELECTRICAL CONNECTORS (6/16/09)

> I am looking for a source and part numbers for the PowerMaster brake  booster wire harness connectors. There is a three pin connector that
> mates with the pressure switch and a four pin connector that mates with the motor relay. If I can find the GM, Delco, Delphi or an after
> market part number maybe I can cross it to something that is still  available. Thanks for the help. Dave
 
Here's a couple of suggestions:
http://www.gmcmhphotos.com/photos/showphoto.php?photo=4072
and
http://www.gmcmhphotos.com/photos/showphoto.php?photo=4073
and
http://www.gmcmhphotos.com/photos/showphoto.php?photo=7907

HTH Larry  :)

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Interesting problem, what happens when you are in Remote, Or. and your Powermasted goes out....... cannot find parts....hummm  I guess the problem is, the powermaster is not a redundant system, it is now a primary system that you cannot do without...

I guess the same would be true with a Hydroboost system.gene

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  Ed Daniel did some demonstrating of the Dana Compressor at Marion. He lives near Buffalo, NY and his phone number is 716-652-8813. He will modify a set of heads for $10.00. He also rebuilds the compressor if you want and rebuilds Powermasters and adds the external switch.
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 'ADVANCE AUTO PARTS'
 WOW!!! Their price was $175 (plus $30 core) AND THEY 4 OF THEM ON THE SHELF AT THEIR WAREHOUSE!! It even comes with a 'LTD LIFETIME WARRANTY"!! Thom

PartsAmerica shows part numbers for rebuilt Powermasters
http://www.partsamerica.com/ProductList.aspx?parttype=250&ptset=A&searchfor=Power+Brake+Unit
Jim Moore (8/22/05)

Schematic

REBUILD KIT (8-30-07)
http://www.resleeve.com/booster.htm

Connections
 The Power master unit indicates that connections on four way plug:

A.  ground and to pin c of combination valve.
B.  Battery (pink/w black tracer)
C.  #30 Amp fuse to battery (orange wire)
D.  to pin A of combination valve

There are some other wiring changes that have to be made to the power master unit to make it work reliably with the GMC coach, as well as replacement of the relay. The original relay was one of the weak points with the design.
Thomas

Bracket
The bracket that is required for the Powermaster conversionis available from:

 Marvin Peck
 8019 Colgate
 Houston TX 77061
 713-643-4442

The cost is around $40.

Powermaster 2 is the one you want as the later Powermaster 3's price is higher by a factor of 4.  According to the rebuilder, functionally they are the same.
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After some extensive online searching for a powermaster brake booster, I finally found it available at www.autozone.com for $155.99.  The part is for a 1986 BUICK ELECTRA ESTATE WAGON w/ 5.0 liter engine.  It is a difficult part to find on their web site.  You must do a "Browse By Part Name" search.  Click alphabetically on "B" for 'Brake Power Booster' then on the #5.

Select "Brake Power Booster".  It will then ask if you want it with "WITH POWERMASTER (PUMP CONNECTED UNDERNEATH RESERVOIR)" or if you want "Vacuum Booster".  Select "WITH POWERMASTER (PUMP CONNECTED UNDERNEATH RESERVOIR)"

With Tax, shipping and core, Total came to $213.61 shipped to my door. Larry 

 DIAGNOSTICS

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Just for the record, for those interested in what vehicles the Powermaster came on, a direct quote from the recall bulliten:

MODELS AFFECTED:
1985 REGAL 3.8L TURBO (ENGINE VIN CODE 9) AND RPO LM9 BRAKES
1986-87 REGAL 3.8L TURBO (ENGINE VIN CODE 7)
1986 LESABRE AND ELECTR ESTATE WAGON
1986 CHEVROLET CAPRICE STATION WAGON
1986 PONTIAC PARISIENNE WAGON
1986 OLDSMOBILE CUSTOM CRUISER STATION WAGON

This can be found at:http://www.gnttype.org/techarea/brakes/usrecall.html

HTH someone. Larry  :-)

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