The following several posts describe the work I did on my brakes from November 2010 until March 2011. I divided it into several posts (BRAKES I - VII) because I can only upload five pics per post.
BRAKES I.
After about a week of fooling around in the street, I managed to get the truck into the garage to begin "real work". I suppose I could have just taken everything apart and started from scratch, but I wanted to evaluate the condition of the equipment, identify specific problems, and then do the work that I found necessary in a systematic way.
Checking out the brake lines I found:
Rear system: Rear line kinked at the wheel cylinder connection (WC) on the passenger side (PS). Main line rubbing on exhaust pipe at frame crossover.
Front system: Evidence of a leak at the tee fitting on driver side (DS) (before and after pics). PS hose cracked.
Master cylinder (MC): Very rusty, fluid very dirty (replaced by clean fluid in the pic). A tee fitting at the MC rear port with branch line into the cab.
I sucked the muck out of the MC with a vacuum bleeder. I use the vac thing now and again but I usually have better luck bleeding the brakes manually, so that’s what I did. I bled the rears and watched streams of black gook pour out, but not much air. The kinked line allowed fluid to pass and wasn’t leaking. Once the fluid ran clear, I moved to the fronts. I couldn’t get any flow at all, so the WC orifices were probably blocked. I cleaned all the crud off the tee fitting, put in new hoses, rebuilt the cylinders, cleaned up the backing plates, installed new stuff (BRAKES II), and tried again. I decided to rebuild the old WCs before installing new ones so I could continue to flush and pressurize the system without worrying about damaging new WCs. The fronts then bled OK, but I still had a way soft pedal, so I was probably seeing only MC problems now.
I removed the MC and bench bled it. I made an MC bleeding system with plastic tubing and flare nut/steel tubing fittings. I figured this was a good exercise and I wanted to know that all the air was out of it anyway. Then I reinstalled it and bled once more.
I found that if I pushed the brake pedal down quickly, I’d get about an inch of firmness at the bottom of travel. If I pushed the pedal down slowly, the pedal always sank to the floor. Pumping helped little to none. I then tried this with the MC outlet ports plugged and got the same results. Conclusion: replace the MC.