I have a 1989 Chevy Cheyenne C1500, it has a 4.3L V6, 2WD, Manual Transmission. I am having a problem with brake drag on driver side front tire. I have replaced the caliper on that tire and i have replaced the brake pads and the caliper wont release. If i jack up the the truck until the tire is off the ground the tire will not rotate. If i take off the brake caliper that rotor will rotate fine. When I put a C-Clamp on the piston to push it back into the caliper it wont move. If i remove the brake line from the caliper I can get the piston to retract into the caliper. When I reattached the brake line i can get the caliper to bleed just fine. After reattaching the brake line and the caliper but before I bleed the caliper the rotor will rotate, after bleeding the caliper the rotor will not rotate. Before bleeding the caliper i rotated the rotor several times and it does not seem to be warped, it will rotate and never get any closer or further from the brake pads. This behavior leads me to believe there is not a block in the brake line because I have no problems with flow into the caliper. The front passenger side caliper functions normally. I can get the front passenger side piston to retract into the caliper with the brake line still attached. After jacking up the car the front passenger tire will rotate without a problem. When I replaced the brake pads I replaced both front tires. My question is what would cause this? Did I get a defective caliper? Is it the master cylinder? But if it is the master cylinder why is it only doing it to one wheel?