There's two hydraulic circuits and two pistons with lip seals in the master cylinder. If only one seal is damaged some pressure will build up against the brake pedal. There is a spring inside to create that pressure which forces some brake fluid to go out to the two working brakes.
What you should be able to do, with a helper, is to have them pump the pedal rapidly a few times, then hold it down with just normal foot pressure while you open a bleeder screw. You should get a little spurt of fluid and the helper should feel the slight movement of the pedal. Do that for each wheel. If you find one front brake and the opposite rear brake don't give you that nice spurt, suspect the master cylinder. If you DO get a good spurt from all four wheels, there is likely still air in the line.
You should only have to bleed the line that had the leak, not all four of them unless you let the reservoir run dry. Even then I never bleed at the wheels. No air is going to travel to the wheels that didn't have a leak. Simply working the brake pedal a few times will wash up any air bubbles that might have gone a few inches down those lines.
Monday, May 28th, 2012 AT 9:09 PM