My brake caliper holds pressure when I mash the brakes and the only way to get it to release is to open the bleeder and push the piston in. I put another junction block (used) on and it still holds pressure. Could the problem be in the master cyl? This is on my 87 truck, please help before I buy parts that I dont need.

C'mon guys, I know there is someone that works on other cars besides camaro's.

a work step-van that i've worked on had the same symptom, the rubber line to the caliper was bad. it would collapse and not release, changed the line,bled the brakes, and it was fine. not saying thats your prob. but its worth a look.

Mike

Crack the line on the master cyl, if that releases it, then the master cyl is causing the problem. If the MC is the cause, then check that the master cyl is returning fully, if it doesn't the fluid can't vent back to the reservoir. First check that the brake light switch isn't preventing full pedal return, then check the pushrod at the pedal and then master cyl where it bolts to the booster. If you loosen the two nuts that hold the master cyl to the booster and the caliper frees up, then it's a pushrod travel problem.
David

Crack the line at the caliper, if it loosens, change the rubber line, if not, change the caliper.

If it is one side, my $$ is on hoses - but replace them both.

Thanks everyone, the rubber hose had collapsed! Something this easy had me scratching my head, and I call myself a mechanic!:clonk: