the v8 s have an electric pump that pushes water around even when You first start it not sure about the 6 ,change the thermastate and the tank they crack and there hard to tell if there bad also ur climate control seems to be going bad its in the passenger footwell to the left in the heater houseing ,i ts metal and has alot of long points on it .The thermastate sticking on You ,I would change that first then the hoses then the tank,If the caps off it wont over heat thats how YOU got it home