Powermaster Issues...

[KrisR]

My friend's '87 Limited T has a problem with it's powermaster unit.

Brakes became soft and the 'BRAKE' light would come on under moderate braking. Then, the brakes suddenly became very hard and the brake light is now always on and the pedal is stiff.

Meineke didn't want to look at it, and said to bring it to the dealer. He did, but they're having trouble diagnosing it.

A fuse in the system keeps blowing. If the fuse is replaced, the system 'pumps itself up' (their words) with pressure until the fuse blows again. They think it's the Accum. ball and/or a thermal switch.

Anyone have any ideas? If we can't figure it out, we'll buy a complete unit off the board here, but if it's something simple, it would obviously be better. He doesn't want to waste money on something that won't fix the problem.

Thanks,

Kris

 

[turbofish38]

Sounds like the pump and motor are going out. If the pump cant build enough pressure it will overheat causing the fuse to pop. If you have the car at a GM dealer have them refer to service bulletin 93-5-107 for the latest procedure to diagnosis powermaster problems.

 

[Matt_S]

POWERMASTER

HI KRIS! This is bob from POWER BRAKE SERVICE. The POWERMASTER was used by G.M. on this supercharged car because vacuum is the opposite of manifold pressure. If the stck Regal vacuum booster would have worked, G.M. would have used it. The POWERMASTER'S motor pump pumps brake fluid, which has no lubrication. The pump uses phenolic vanes, which wear out. The pressure switch holds the pump on until it reaches 2400 psi into the accumlator. If the pump can't reach the 2400, it keeps running. Then the seals wear out, and brake fluid enters the motor and shorts it out. We can rebuild the booster/master portion of the powermaster, but the motors are sealed. The only motors available are used ones, which i have several. The stock regal vacuum booster would work, but vacuum is weak, and the booster's output is low. You could add a vacuum pump, but they noisy, burn out in 6 months, and expensive. We recommend converting the car to mthe HYDROBOOST system. This unit is fed pressure from the power steering pump, and requires no vacuum. It actually was used on G.N.'s in 83-85, for the same reason; NO VACUUM! The POWERMASTER was an attempt to save installtion time at the factory. The HYDROBOOST can run trouble free for 200,000 miles, run 4 wheel disc, if you like, and stop incredible! It is the perfect complement to the Baer conversion, with stock brakes, or any combination you would like to try. The HYDROBOOST color photo is viewable on the website powerbrakeservice.net, or call 800 504 1060

 

[KrisR]

Nevermind - he just sold the car.

Thanks for the info anyway,

Kris