Well I have a 85 toyota pickup with the 22re motor. I was driving down the road and the heater hose that goes to the heater core front value popped. I replaced it but now it over heats. It only over heats when it just is warming up from being cooled. It will be fine for a minute but then it will warn up and hit the red on the gauge. But I did find out if I turn then heater control to cool the temp with go down intantly and then I can turn the heat back on and it will work correctly. My question is, Is there a valve that is broke or not working right?