Front passenger disc brake is locking up

[Timothy Knutsen]

Just replaced calipers, rotors, and pads on front brakes . Obvious prior trouble with passenger side front brake as outside pad was down to metal and thinned out rotor. Just bought this truck which had sat for 5 years on the north coast in Humboldt county.  

After replacing brakes same apparent problem with right front brake locking up and getting hot. Only drove 1/2 mile and parked it.

Any suggestions so I (dont destroy)can keep my new parts?

[davester]

it's not unheard of for the rubber hose to the caliper to fail, so that it doesn't allow the fluid to return from the caliper. 

[Doug_Scott]

Easiest way to diagnose this problem is to take the truck for a drive until you feel the brakes dragging.  Stop and turn the steering wheel to give you access to the bleeder screw on the caliper.  Open the bleeder screw while watching to see if brake fluid squirts out, and the brakes no longer feel like they are applied.  If that releases the brakes, chances are the flex hose has failed.  Also check the other front wheel before loosening the bleeder screw.  If it also seems to be hanging up, see if it also frees itself up after loosening the bleeder on the right front  wheel.

There are only a few causes of what you are seeing.  Defective caliper, old flex line, defective caliper sliders, and a partially plugged compensating port in the master cylinder. The last item is quite rare, but, I have seen it more often than a flex line with the inner core acting as a flapper valve. Easiest way to test compensating port is to remove master cylinder cap, wrap a rag around the master to catch a squirt of brake fluid when you have someone step on the brake pedal.  You should see a squirt of brake fluid come out the open master cylinder reservoir for the front brakes.