i have a 350 motor a 72 vette motor i heard a sound that sounded like a exhaust leak it would go with the truck as i sped up and slowed down.come to find out it is air escaping were the head meets the block on the corner back side im not over heating not milky water at the rad cap just air comming out and it looks like oil leaking as well is the head gasket bad and do i need to replace it. is it bad if i drive on it for a week r so untill i can fix it