Originally Posted by m735is

Is there any coolant in the oil? Remove the oil cap and look under it, is it white? I removed the oil cap, didn;t see white in the engine.
Any excessive presure building up in the coolant system from gases entering it?

Where is the coolant going? Is it overflowing from the expansion tank or anywhere else? If not, you may be burning it. How's the exhaust smell/look? The coolant was boiling and flowing out from the expansion tank. I am not sure if the exhaust smells abnormal. But, there was white smoke coming out of the exhaust.

The water pump may be bad, if you see coolant leaking out the weep hole of the pump, then it's bad.Didn't see coolant leaking

You could have a bad t-stat (even though it's new) or rad cap. It could just be air trapped in there, did you bleed the system?I am quite sure the t-stat is good since I tested it by putting it in hot water. How do I bleed the coolant system? When I drained and refilled the coolant, I turned on the car, kept the rad cap off, and let the car idle for a good 30min. The coolant was boiling when i put the cap back on.

You may have to have compression test and/or leak down test done to find out if the head gasket is bad.

How long does it take to start over heating? My aux fan rarely runs-especially this time of year.