here's a follow-up to my post. Today I was out driving when it was 95 degrees out. The temp was ok, but I went up this 2 mile hill and the temp went up to 3/4.I stopped and looked at the engine and there was some steam coming out of the overflow tank and a hissing sound. Can this overflow tank thing be bad or is this a symptom of a combustion leak into the coolant causing high coolant pressure? I have the tests scheduled for tuesday(leakdown, combustion test of the coolant and coolant system pressure test)