I agree with directfreak. I think he has air in his coolant system. All you need to do is loosen the cap (dont take all the way off) and start the car. Let it warm up a little, and check the coolant level. I bet it went down some. Air gets trapped in the block and doesnt like to come out with ll that pressure in the system. Happened to my friends mx-6 after we changed the head gasket.

 

Also check the incredibly obvious. Look to see if theres debris on the radiator. Like a plastic bag you may have sucked up.

 

No debris blocking the airflow. I filled up the rad. There shoudn't be any air left. All the excess was moved to the reservoir. I'll flush it soon. This fuel isn't going away fast enough.

 

Start the car and IMMEDIATELY go under the hood... Put your hand on the upper radiator hose... Wait... As the thermostat opens, you'll feel it warm up... If it doesn't warm up in a few mins, replace the thermostat. Now. Feel along the bottom of the radiator... It should be evenly warm... If there's cold spots, you have a plugged core. Back flush it or replace it.

Always when refilling the system after it's been empty, I fill it and start the car with the cap off. Let it warm up till the thermostat opens. That'll burp 90% of the air out of the system. The rest comes out over the next week of driving, so I keep coolant with.