I just finished my battery rolocation and now I have a hissing sound when I turn off the car. I didn't loosen anything in the engine bay so I'm stumped.
Radiator cap not on tight? Vacuum hose get pulled accidently? Heater - A/C control still turned in position besides "off"? A/C drain pipe dripping water onto header pipes? Get a hole in one of your tires? Late night boozin at Club X perhaps had you orally relieving yourself on your header pipes and you don't remember a thing