My 91 Civic presurrizes the cooling system upon startup. The overflow
tank is also under pressure and there is a slight leak under the cap.
There was also a spare cap under the hood when I bought the thing not
long ago. Is this pressure normal or is the head gasket going? There is
no oil in coolant, no coolant in the oil, and it doesn't smoke. It runs
good and doesn't overheat. But if you start it with the cap off it
sprays coolant. Should the overflow tank be vented? I only see one hose.
THanks in advance.