Chrysler Repair: Sudden Overheating, head gasket leak, coolant system

Question
QUESTION: Hi there-
I have a 2005 Sebring Convertible, 2.7 L engine. The car started overheating while driving home from the gym today [rainy/overcast around 80 F].  I can't find any leaking fluid, but lost about a gallon of coolant through the overflow.  No cracked gaskets, overflow cap looks fine.  I checked the fuse for the radiator fan and it's fine.  Any thoughts?
Thanks so much in advance -
Jim

ANSWER: Hi Jim,
It could be the thermostat is stuck closed, or the radiator is plugged up, or possibly that you have a head gasket leak and so the coolant system is being pressurized due to the compression of the pistons being 'felt' in the cooling system.
Was this associated with overheating or did it come on very quickly after a cold start? If the latter, I would be suspicious of the head gasket leak. See if you get excessive white smoke from the tailpipe when you start the engine from cold, as that is the tell-tale, and also listen for early bubbling sounds in the cooling system within a few minutes after starting the engine, another sign of that same source. Also look for foam/cloudy engine oil.
The radiator should be about equally hot comparing the side manifolds with one another. One side cold would suggest that you don't have good cross-flow.
While the fan fuse is good, did the fans come 'on'.
Those are the possibilites that come to mind. Let me know what you observe.
Roland

---------- FOLLOW-UP ----------

QUESTION: Hi Roland -
Thanks for the very quick response.  To respond to your questions:  1- It came on quickly after a cold start and the car next to me noticed the steam at a stoplight.  I hadn't been in the car for more than 5 minutes, and traveled less than a mile from the gym.  

This morning I started the car and let it run for about 10 minutes or so.  The car didn't overheat [not sure how long it would take sitting and idling].  There wasn't any white smoke from the tailpipe [just a small amount of what looks like water vapor, but that stopped], nor did I hear any bubbling sounds in the cooling system.  The side manifolds feel equally warm.  I read somewhere that the fan wouldn't come on until the car reached a certain temp, so I turned on the A/C and the radiator fan worked fine.  The engine oil looks normal as well.  Could this just be a fluke?  I am a little leary about driving it...
Best,
Jim

Answer
Hi Jim,
An intermittent malfunction is a problem. How about the coolant filler cap being ajar when this happened or perhaps a worn gasket on the cap? In the meantime, carry some spare coolant and drive locally until you regain confidence or the problem re-occurs.
Roland