My Truck was vandalized a few days ago and I had to drop the gas tank and clean it out (sugar and rotten milk in tank) and it was running fine after that, I never started the truck in the first place, well next day the top radiator hose blows apart and I replace it, fill the radiator with antifreeze and water until it cant hold anymore, then seal it and run the car a few miles.. it doesnt over heat at all, but then I park it for about 20 mins and go back outside to drive it again, it overheats in a matter of 5 mins!. so i pull over and decide to do something stupid. I unscrew the radiator cap and let the steam pour out, thinking it may just have way to much pressure, The engine instantly cools down and im able to drive home, I noticed on the way home the temperature started to get a bit to high again. What could be the problem? by the way the radiator cap is in the middle of the upper hose and not attached to the radiator itself.