1990 Chevy Astro CREEPING BRAKES

Bench bleed the master by getting brass plugs and screw them into the two ports, then pump the master until you cant move the piston any more. Attach the lines, Have an aide press and hold the pedal crack the lines and retighten, repeat this till all air is removed at the lines, Don't let the master run dry, bleed rear cylinders by opening the bleeders and wait until the fluid dripps out. Close bleeders. Make sure the rears are properly adjusted, then test the pedal hieght You still have air, or a leak.