Still broken. I don't think you can put the heater core hoses on inccorrectly their connected short and long. Got alittle heat out of the vents but only for a moment. Water would pumps out of overflow tank every minute or so. I didn't drive the car so it didn't overheat. The overflow tank bubbles and like I said fluid occationally pumps out. I think there's a crack somewhere, but where?

 

I could be completely wrong, but could it possibly just be the resivour cap?

 

You know I had this same problem no too long ago. I replaced my thermostat and didn't bleed the system.... and oh yeah, I learned that you can put the thermostat in backwards

 

What else have you done to the truck?
I re-read your post and you may have a blown head gasket.

 

I put new head gasgets on last fall, machined heads, pressure tested, new lifters, rods, wires, water pump, drove for two months, 2,000 miles no problems then overheated. Machanic put on new head gasgets, machined heads pressure tested, started up, overheated, mechanic did again with a different head, same problem. Towed car back home put on thermostat and new cap, here we are.

 

I would look into the radiator being clogged then.