Toyota Repair: toyota 83 pickup, brake master cylinder, brake calipers

Question
about 5,000 miles ago I bought a 83 pickup with rebuilt engine (22r) brakes, clutch . overnight the brake pedal goes to the floor the first push but will pump up. there is no leaks around the wheels and the reserivor is full. bled front brakes to no avail. Help? Brakes worked fine til this.

Answer
If there are no external leaks check the brake master cylinder, remove it from the brake booster and check for a leak. If not, check the front brake calipers,this is a two piece caliper which uses sliding pins to let the caliper move as the pads wear, make sure the caliper part that has the piston in it can move on the pins, if that's not the case replace the master cylinder, it may have an internal problem.