Maybe this is what you are experiencing, but less severe.
I had a huge problem when I first started driving my 65 C10. It had a new single reservoir brake MC and no booster. The brakes would get hot and would drag. I could release pressure from the rear lines through the bleed screw and all would be fine for another 10 minutes. Then the brakes would get super tight again.
I had the MC pushrod adjusted a wee bit too tight and the MC plunger was not quite getting back to the home position. So every time I would brake, the pressure in the lines would build slightly. After 10 or more braking events, they would be super tight and of course by then the shoes were dragging on the drums constantly.
Letting the truck sit 10 or 15 minutes was enough time to let the pressure disappear without touching the bleed screw. I was puzzled for a few days, but I will never forget what I learned.
Last edited by Lugnutz; 09/24/2017 7:38 PM.
