i have recently noticed a hissing noise that comes from my radiator. ALso my engine heats up real quick and it doesnt take long for the needle to rise at all. This may not be related, but my gas tank needle is way below the empty mark and fluctuates from taht position to where i actually have gas-could any of this have anything to do wtih my very loose and shot cat?( i dont think so but its worth a shot)

Thanx