Hey guy I'm having some problem with my 99 wj 4.7L i just put in a rebuilt 4.7L after sitting for almost a year and a half. after driving it for the first time i noticed my brakes were not releasing so i replace the caliper and had the rotor turned bleed the whole system twice and i still can't get it them to release all the way i hear the brakes rubbing when I'm driving.

My thought were the it could be the master cylinder or the Proportioning valve but I'm not a 100% on either. Any thoughts?

 

Rubber brake lines to the calipers. Inner wall deterioration can form flap-like obstructions that act like one way valves. To test for this, jack one wheel off the ground, spin the wheel, have a friend tag the brake while you feel the drag. Does the drag free-up when the pedal is released? Crack the line fitting and if that frees the wheel then the line is bad. Repeat procedure on other side...