Background: 1968 C60 full-length schoolbus. Sat for 4-5 years until I bought it, and has no brake pressure. Have been trying to bleed the system for a few months, without success.
Brakes: 4-wheel drums with two separate lines/bleeder valves on each wheel, one top, one bottom. Split master cylinder. The inside of the master cylinder cap has two rubber boot looking things, one of which says "fluid side". There are two large cylindrical tanks underneath the driver's side of the bus, toward the front - are these vaccuum boosters?
Symptoms: little or no brake pedal. in the process of trying to flush the system, have had sporadic pedal improvement followed by complete loss of all pressure again. sometimes when I go to refill the master cylinder, the fluid is foamy from air bubbles.
Method: per the wisdom of various stovebolt posts, I have been working from the wheel most distant from the master cylinder to the closer ones.
-I fill both sides of the master cylinder about 2/3 full, and retighten the cap.
-open the top valve on the right rear wheel
-have a friend pump the pedal to the floor 4-5 times and hold it
-repeat the previous step several times, usually a lot of air and some fluid comes out
-on the final pump, the friend holds the brake pedal all the way down and I close the valve
-repeat steps on bottom valve, and switch back to top valve several times.
-work my way around the bus (sometimes only the rear two wheels in a given setting), but sometimes I switch wheels while there still seems to be in air in the lines of the current wheel.
I dont get it, it seems like whenever i make progress, soon afterwards the pedal gets even worse. Should I be pumping the brakes with the bleeders closed before I open them? Is one side of the master cylinder supposed to be dry?
PLEASE help me, I need super-detailed instructions on how to properly bleed these brakes and any tips on what i might be doing wrong
