I would like to raise a simple 'truth'...
When the Master Cylinder is at rest (with your foot off the pedal and the spool is retracted
), the lines are open to the reservoir(s), to allow brake fluid to return as the shoes and pads retract.
Conversely, if the spool is held in for any reason, the reservoir is blocked off and pressure is allowed to build in the lines.
There are two adjustments that can hold the M/C spool in:
The brake pedal rod at the pedal bolt,
The booster output rod (between the booster and the M/C).
Proper setup and adjustment for both areas are covered in the Service Manual (that nobody reads unless they have to).
Originally Posted by jopizz
... Since you said the master cylinder was rebuilt I would look at that as the culprit...John
I agree, John. It is possible the spool is not retracting all the way, internally. I would want to see the spool hit that snap ring.