Powermaster cycling

[N2BUICK]

Is there some number of how many times a power master will cycle ? Mine is cycling every 2 to 3 minutes with just the key on and not touching the brake.
Car stops good has decent pedal.

 

[TurboDave]

Sounds like the check valve is starting to leak down.

 

[N2BUICK]

Dave
Is a check valve something fixable ? I have at least half dozen used power masters laying around. Surely I could find a good part ?
I even have two GM repair kits if needed, dont think there is a check valve in those kits?

 

[1quick6]

Sounds like a slowly leaking accumulator to me.