de6w6it

I just joined the forum because I just bought an 88 4runner. I drove it home 60 miles and couldn't be happier. I have wanted one for the longest time, and finally found one with a good motor and solid frame. Problem is this:
I was pulling away from my house, hit the brakes, and the pedal went to the floor. From what I could tell, it was one of the two lines running back to the load sensing proportioning valve. Since no one seemed to have or be able to get lines for me, I bent my own, and replaced that line. Then I bled the brakes, and the pedal still just went to the floor. Then I replaced the master cylinder, and tested the new one by plugging the two ports, and it held pressure, so I know that is good, but the pedal still goes to the floor. I have bled it over and over, using about 4 quarts of brand new dot3, and as far as I can tell, there are no leaks from any of the lines. The wheel cylinders at each corner are relatively new. The pedal still goes to the floor. The weird thing is that if you pump the pedal a few times, it stiffens up, and if you keep your foot on it, it wil hold that pressure. But if you let off, and then press it down after a few minutes, it goes right to the floor. It will not do this if the motor is running, it always goes to the floor and will not hold that pressure like it does when the motor is off. If you pump the pedal with the motor running, the rpms drop, and the pedal will not hold any pressure. The manual says something about a check valve, but I have no idea where it is or what it does.
I know this is long, and anyone who reads this I appreciate it very much. If anyone has any suggestions for me, I would appreciate it a whole bunch. hanks in advance for any tips or suggestions.
DeWitt

eric-the-red

Sounds like you still have air in the system. Did you bleed the load sensing proportioning valve as well. It should be done last, after all 4 wheels.

de6w6it

my truck is about as rusty as they come, and the bleeder in the lpsv is pretty stuck, and i did not want to snap it off. i sprayed it with some pb blaster and am waiting for it to soak through, so i will bleed that next. i will post my results. thanks for the suggestion

nate V

I had the same problem when i did my brakes this winter. all four wheels will bleed fine when the peddle still goes to the floor. Finally beld the height sensing valve and it worked fine.

de6w6it

yep, bled the lpsv, and i am golden, thanks for the help guys, i really appreciate it