basketcase0302 wrote:
The power brake booster was working fine when i started the build last October, although I haven't hooked the vacuum line back up to it. I'll do that later this morning. That shouldn't matter should it? Seems like I remember having a pedal even without the engine running and booster hooked up?
I broke my mityvac bleeding tool a few months back attempting to bleed all the lines, (I can't even get enough pedal to bleed the lines at present)!
No, the engine does not have to be running to bleed the brakes. Remember, when an engine dies, you have about three brake applications before all vacuum is used up, then you have to hope you have a strong leg to get the vehicle stopped on just about any vehicle. 
basketcase0302 wrote:Do I remember reading about "recentering" brake distribution blocks?
Or does this only apply to a proportioning valve?
The plunger in the distribution block DOES have to be recentered, but that’s to turn off the warning light on the dash. However, if it sticks to one side or the other, it CAN cause problems with either the front or rear brakes.
The problem you’re having sounds almost like the master cylinder isn’t returning to the home position once the pedal is depressed.
Have someone press the pedal while you watch the fluid in the master cylinder. When the pedal is released, you should see sort of a “fountain” of brake fluid as the pedal comes back up. Since you said the master cylinder works fine for a bench bleed, it should provide the same results on the truck.
If you don’t get the “fountain”, check to make sure that the push rod on the master cylinder side of the booster is working correctly. If it’s not seated in the booster correctly, it will hold the master cylinder piston in the “applied” position. Did the master cylinder slide easily all the way against the booster when you installed it, or did you have to pull it up with the nuts? Pull the master cylinder off and make sure the push rod length is correct. Measure the distance from the mounting surface of the cylinder to the bottom of the piston, then measure how far the push rod extends past the mounting surface of the booster. Those two measurements should be pretty close. While you’ve got the master off of the booster, have someone press the pedal while you watch to make sure the push rod moves with the pedal.
If all of this is good, loosen the bleeder screws on all four wheels and let the system “gravity bleed” for a while. Since you replaced all the hydraulics, there may be so much air that you’re just not giving the fluid time to get through all of the system. Not probable, but possible.
A trick I learned a long time ago was not to do the “classic” bench bleed when replacing a master cylinder. I always bolt the master cylinder up, leave the lines disconnected, then fill up one end of it. Then, I have someone depress the pedal while I hold my finger over the corresponding port. Once I have all of the air out of that section of the reservoir, I connect the line and loosen it slightly while the brake pedal is depressed. Repeat for the other section. It's a LOT less hassle!!!
Since you’re pretty much starting from scratch, once you determine that the booster is working and adjusted correctly, just work on one end at a time, using the procedure I described above. It really doesn’t matter whether you do the front or rear first, just make sure that you start with the wheel furthest from the master cylinder on whichever end you decide to start. Once you have brakes on that axle, do the other axle in the same manner. After you have good pedal, go back and reset (recenter) the valve in the distribution block by having someone depress the pedal while you slightly loosen a bleeder screw. You will most likely find that the end that you started with is the one that has the valve off-centered.
Give this a try, and let us know what happens!!!
