Powermaster Problems

[desertgn]

I've been reading tons of info on the Powermaster and the problems that come with it, but I can't seem to pinpoint the problem that I am having to a specific part, it has all been very confusing. To put it simply, sometimes the pedal goes all the way to the floor and the car will barely stop, and sometimes I get a very hard pedal reaction. Does anybody know the specific solution to this problem besides eliminating the Powermaster, which I am considering, but I would like to know if anybody knows the exact cause of this problem. Thanks.

 

[gofstbuick]

knowing that a properly operating PM system provides very good brake assist, do you hear the PM motor run? Have you done anything to the brakes lately? If so, first thing to try is bleeding the brakes and adjusting the rear shoes.

 

[desertgn]

Yes, I do hear the motor running, and no, I haven't done anything to the brakes. This problem just seemed to pop up one day and I have basically parked the car because it's just not safe. I don't see any leaks anywhere either.

 

[Terry_H]

It sounds like the accumulator ball is bad. Those were my symptoms. The accumulators have a finite life span of about 5-7 years. I've since sold the powermaster and am now using vacuum.

 

[Real-T]

If the pedal goes all the way to the floor, it is likely an internal leak in the cylinder. Perhaps one of the seal rings has failed or is failing and will require a rebuild.

The hard pedal could be due to the accumulator not being charged enough and failing as well.

Has you powermaster ever been serviced or repaired in its lifetime ?

Also the gnttype.org site is up and running again and is a great source for info.

There are some troubleshooting flow charts that can help you pinpoint the problem and you can make a decision as to what to do. Here is the direct link:

http://www.gnttype.org/techarea/brakes/brakespage.html

 

[desertgn]

Other than the initial recall, the P'master hasn't been serviced, at least that I know of. I've had the car 3 years now and have babied it most of the time. I am considering going the hydraboost route, but if this problem has a simple solution I was going to fix it that way to keep the originality in tact. Like I said I don't see any evidence of leaks, the fuse is not blown, I'm stumped.

 

[turbojd]

The power master unit is expensive crap anyway, you'll just keep replacing expensive part after part. I converted to vacuum brakes after a couple scares of almost not stopping due to parts failing on the power master.

 

[TURBO2]

Is your Brake Idiot Light on or off?

 

[gofstbuick]

What color is the brake fluid? Black and cloudy? If so, then that material is all over the inside of your mc. Rebuilding the mc may help, but you're probably still going to need an acumulator. Others have switched to vacuum or hydroboost with a lot of success. My advice to you is to do a search on vacuum and hydroboost, then make a decision. I can tell you that my PM system is marginal and once it goes, I'm switching the hydroboost. I already have a newly resealed unit (with master cylinder) and a hose assembly. It's just a matter of time. The vaccum units requires a pedal change, but many members have successfully switched to vacuum (if it's good enough for a TTA, then it should be fine for a GN) and are brake trouble free and the same goes for hydroboost. Initial cost for hydroboost is probably more expensive, but units are readily available from 84 and 85 TRs.

 

[desertgn]

The fluid is black. I'm convinced that the best thing to do is just change out completely. I don't want to be messing around with this system forever, I want to drive my car! I'm leaning towards the hydraboost system.