Gurgling In Heater Core

Hi: I have a PT Cruiser convertible touring edition turbo charged. I recently had the radiator replaced, after 3 days the car overheated for a few minutes shut it off and let it cool down. Drove it home and it did it once more. The next morning I removed the radiator cap and a burst of air came out. The car has not overheated again. It has been 5 days, but, when I shut it off sometimes it does gurgle for about 10 seconds. I do get a faint odor of antifreeze outside when I get out of the car. I'am not loosing any antifreeze, I do not have any antifreeze in the oil. No foam built up on the oil cap. No steam coming from the tailpipe. The car runs perfect, no power loss or anything. Could this be a blown headgasket or cracked head ? Or could I still have air trapped in the system ? Please e-mail me with any answer you may have. Thanks Michael