So I checked my coolant the other day after my PVC/air box vent clogging ordeal (topic on here!) since I was pushing out oil I figured I'd check the coolant as well it was a good bit low in the tank added maybe 1/5th of a gallon and its still not where it should be but when hot almost full so its close! Anyways, I noticed a hissing from the cap. Is the cap bad and thus my coolant is evaporating or is the hissing normal for these cars!?