tapping noise from radiator tube?
In the last few weeks, I have noticed twice a tapping noise coming from radiator tube after shutting down car. The noise goes away after about 15 mins. Anyone has any idea what this might be? Coolant level looks ok. I haven't noticed any excessive white smoke from exhaust although it's hard to tell as temperature has been minus here. Engine temp gauge has been normal. I did hear gurgling sound around coolant reservoir once.