Power master brake failure

[SoGrand]

Was reading in the info guide by Peter Hoffman copy right 2005 pg 48. Keeping the brake fluid absolutely clean won't allow the sludge to form and clog the valve. He states to actually change the fluid every 6 months to keep it absolutely clean.
I thought that was bit excessive. I called and spoke to Dennis Kirban personally to see about another brake assembly as everyone else has as per what they all say. I thought for sure he would just say yes you need this and this. He did' t. He told me that the GM people never told the public about the fluid. He said the same thing as Hoffman. Keep it abosolutely clean and you will not have any problems. That the power master is actually a good system but has to stay clean. I had this conversation with Dennis just a couple of days ago. My fluid was a little dark so I changed it and bled the system clean. I only have 29,600 miles on the car. He said that most people that have had problems were the ones with many more miles than that. There was no muck in the master cylinder bowl before I bled and cleaned it so maybe it'll be ok. I'll work on it as they both suggested. Maybe the power master is getting a bad rap. Guess I'll find out!

 

[BEATAV8]

Clean fluid helps a lot but it won't prevent the switch from failing. Keeping the system running and in use requires some close attention, a good understanding of how it works, and some pampering.

keep the fluid clean, use synthetic fluid
make sure the switch cycles the motor as expected. if it starts to act up, replace it before it craps out.
use a hydac accumulator. they are better than the originals.
discharge the system pressure if the car is going to sit unused for weeks or months

 

[SoGrand]

Clean fluid helps a lot but it won't prevent the switch from failing. Keeping the system running and in use requires some close attention, a good understanding of how it works, and some pampering.

keep the fluid clean, use synthetic fluid
make sure the switch cycles the motor as expected. if it starts to act up, replace it before it craps out.
use a hydac accumulator. they are better than the originals.
discharge the system pressure if the car is going to sit unused for weeks or months

We can still get parts for this unit?(switches, etc)

 

[626gn]

We can still get parts for this unit?(switches, etc)

You can no longer get a new PM motor unless you can find someone who has hoarded one. New switches and accumulators can easily be found but the cost is comparable to a complete vacuum system if you shop around. Which is why many go that route (or Hydroboost), if not purely for the peace of mind...

 

[626gn]

Clean fluid helps a lot but it won't prevent the switch from failing. Keeping the system running and in use requires some close attention, a good understanding of how it works, and some pampering.

Agree. I changed the fluid religiously every 6 - 8 months for years and still experienced accumulator failure (it was the original accumulator with the yellow silkscreen design). The brake switch never outright failed on me but began leaking at the terminals. Although I was not the original owner of the car and did not start the every 6 month change schedule from when it was new, these parts would have needed to be changed eventually. Much sooner than expected if the unit was poorly maintained. Its just the nature of the beast with this system.

I do agree that keeping the fluid fresh is the single most important thing to keep on top of if you have a Powermaster. 98% of engine pics I see on this board shows dark fluid. The fluid should never be allowed to get dark. Like BEATAV8 mentions, anyone with the original accumulator should change to the new type. I have not heard of any failures with those.

 

[BEATAV8]

Switches and accumulators are easy to get. master cylinder seals (internal) can be bought from Karps power brake service.

new pump/motor assemblies are nearly impossible to find. last brand new one I saw was last year, came from oldbuickparts.com

A fella named Hank Terry had the tooling and was making them about 15 yrs ago, then the stuff went to Maval gear, now it's a mystery where the tooling is.

Highway Stars is working towards releasing a complete brand new powermaster assembly. There's a thread about it somewhere around here.

 

[gsgnnut]

1. I had failures with clean fluid. No sludge. The units tendency for sudden failure makes it too unpredictable and down right scary. Not worth dying over that technology. i will never use a pm ever again even if they were free. To many bad memories.