1978 F-150 4x4
Has been sitting for a few years now, just got it back up and running. My problem now is the front brakes are locking up. If you drive it for a short distance, the brakes slowly as they heat up become more locked until eventually the truck just stops. Then at this time I get out and crack the bleed bolt on both front calipers. Then its good again for another short distance. Calipers have been rebuilt. I'm thinking master cylinder and or brake booster? anyone had similar problems and what seemed to work?? Thanks

 

Sounds a lot like a brake hose itself. They develop internal defects in the lining with age and then one day a piece of the lining drops and acts like a check valve holding pressure.

Are both sides getting hot? Might be the single line from axle to frame.

Just a thought! Good luck.

 

I've had the rubber hose to the caliper on a GM car develop a crack in the rubber, yet still not leak. But it did the check-valve thing, keeping the brake clamping even after the pedal was lifted.
Lots more pressure when the pedal is pushed down, than when it's lifted.

The only brake hose problem I've seen on Fords has been on the Tempo and Topaz front calipers. On those, the retaining bracket (which bolts to the strut or whatever, and is bent so as to curl around the hose, retaining it and tethering it out of harm's way) will end up pinching the hose, and keeping the front brakes dragging. Dunno if that's from the hose swelling, or the bracket swelling due to built-up corrosion, but simply using a flat blade screwdriver to spread the bracket where it curls around the hose, is a free and easy and effective fix for this phenomenon - I've fixed three of those cars that way...

 

To me sound like the MC needs replacing.
If you think it's the hoes then by open the hard line at the MC should relives the hose pressure,
but if it's still locked up then it's then it's the MC
Orich

 

Or someone monkeyed with it before it was parked and put a M/C on with too long of a push rod

 

I had same thing on my hotrod and it was the master cylinder. I had already changed my hoses. Brake issues can be frustrating .

First thing l did was unhook booster to make sure that wasnt it.
Next l undid the MC from booster when the brakes were stuck and none of the above worked so l was positive it was the MC.