I have some powermaster stuff on my page, with links to others
gene
>
>> Under gentle or 'slow down' braking the brakes seem to work about normal,
>but
>>
>> when I brake hard for a stop I lose most of my braking effect and the
>brake
>> light comes on. Some times it goes off by itself, but sometimes I need to
>> tap
>> the pedal for it to go off.
>
>Justin,
> I confess I've never dealt with a Powermaster, but I'll toss in a few
>ideas FWIW.
>
>1 Usually a failing/leaking master cylinder will show up under GENTLE
>braking with light pedal pressure. That's when the fluid seeps past the
>seals back into the reservoir, and the pedal slowly sinks to the floor.
Hard
>braking usually develops enough pressure to make the master cylinder cups
>seal up momentarily. So I doubt that's your problem.
>
>2 The big question is what does your pedal do when this problem occurs?
>Does it sink to the floor, suggesting a problem in the master cylinder or
>beyond (lines, proportioning valve, etc., air in system, leaks, clogs,
>whatever). Or does it stay high and hard, suggesting a loss of power assist
>from the Powermaster?
>
>3 If you're really suspicious of the proportioning valve, try
>jacking/lifting all 6 wheels and see whether any don't lock up when you hold
>the brake pedal down hard.
>
> Finally, there are some web sites with detailed diagnosis info for the
>Powermaster. (I think the Buick performance site was one. One of the GMC
>sites should have a link.)
> Good luck, HTH.
>
>Rick Staples
>'75 Eleganza
>Louisville, CO
>
>
>
Genef -- 77PB/ore/ca
GMC MOTORHOME INFORMATION
mr.erf
http://www.california.com/~eagle/
gene
>
>> Under gentle or 'slow down' braking the brakes seem to work about normal,
>but
>>
>> when I brake hard for a stop I lose most of my braking effect and the
>brake
>> light comes on. Some times it goes off by itself, but sometimes I need to
>> tap
>> the pedal for it to go off.
>
>Justin,
> I confess I've never dealt with a Powermaster, but I'll toss in a few
>ideas FWIW.
>
>1 Usually a failing/leaking master cylinder will show up under GENTLE
>braking with light pedal pressure. That's when the fluid seeps past the
>seals back into the reservoir, and the pedal slowly sinks to the floor.
Hard
>braking usually develops enough pressure to make the master cylinder cups
>seal up momentarily. So I doubt that's your problem.
>
>2 The big question is what does your pedal do when this problem occurs?
>Does it sink to the floor, suggesting a problem in the master cylinder or
>beyond (lines, proportioning valve, etc., air in system, leaks, clogs,
>whatever). Or does it stay high and hard, suggesting a loss of power assist
>from the Powermaster?
>
>3 If you're really suspicious of the proportioning valve, try
>jacking/lifting all 6 wheels and see whether any don't lock up when you hold
>the brake pedal down hard.
>
> Finally, there are some web sites with detailed diagnosis info for the
>Powermaster. (I think the Buick performance site was one. One of the GMC
>sites should have a link.)
> Good luck, HTH.
>
>Rick Staples
>'75 Eleganza
>Louisville, CO
>
>
>
Genef -- 77PB/ore/ca
GMC MOTORHOME INFORMATION
mr.erf
http://www.california.com/~eagle/
