when I finish a drive...and let the car cool down, I then remove the cap on expansion tank. There is pressure on it so I remove slowly. I get a gurgling sound that comes from that wheel well tank I think??? Is this normal? I took air and blew it into hose that leads down to the tank...got a gurgling sound. Do I need to go in there? I am losing fluid somewhere! New water pump, thermostat, radiator cap.Car does not overheat...but has in the past

Thanks
Warren