brakes not working on a '93 t-100...

[ChrisM]

Problem was first noticed one morning last week... my dad got into the truck and said when he tried to push down the brake pedal it would not depress at all, started the motor and still could not depress the pedal (he said it kind of felt like the pedal was "pushing" back). Then he said he took the e-brake off and even when not touching the brake pedal the truck would not move (it was parked in our driveway which is pretty steep). He then backed up a bit and said it definitely felt like the brakes were engaged, but still could not push down the pedal. After all that, he got it down to the bottom of our driveway, which is level, and pulled the cap off to the reservoir and said the fluid level was to the top, so he said he dipped the fluid out of it until it was back to the line. He got back in the truck, started the motor and said it seemed to work fine after that.
Couple days later he said the same thing happened at work, the only difference was after getting the fluid back down to its mark the brakes were mushy like there was air in the lines.
He got it back home and we tried bleeding the brakes, but everytime you would push the pedal down it seemed like it wasnt moving any fluid. We thought maybe one of the lines might of gotten clogged up with something, so we unhooked the brake lines and took off the fittings and blew air through them, they all seem to be clear of any debris. Hooked everything back up and tried bleeding the brakes again, but nothing.
So now its got a new master cylinder and brake booster. Seems like we got the rear brakes bled, but something still doesnt seem right with the front.
(if you made it this far, sorry for the long post)

Anyone have any ideas to what is going on, or have any ideas on what we should try to do?
Any input would be appreciated.

Thanks, Chris

 

[SEAIRESCUE]

Your brake problem

When you push the pedal, the front calipers move and the rear drums move.
Some Toy reservoirs have check valves at the master cylinder. They have caused problems for me in the past. Also, the rear drum brake designs lend themselves to tight tolerance parts rusting and not moving like they should.
Depending on the miles of the truck, you are looking at age related problems with any or all of the above. If your front wheels lock up, crack the brake lines on the master cylinder to relive static pressure to determine if its the master cylinder causing the problem. If not, I would proceed to the rear and oil all moving parts CAREFULLY with a light weight oil. The self adjuster and the very bottom rotator between the shoe ends is usually the culprit. Lastly, the front calipers may be sticking from rust.
Best of luck,
Seairescue