I had no overheating problems with it before!!!

My 2003 Z06 Corvette; what a strange fix to a common problem.

It overheated in town so I limped on over to a nearby Ford Dealer where they put in a new Thermostat.

The mechanic still had overheating problems though. Kept it another day just tinkering with it. Two days and $250 later I got my car back. Seemed to do just fine (at first).

Then about a week later the same trouble developed again. Turn it on, drive 3 miles, temperature > 250. But it would cool down relatively fast. This tells me that all the coolant in all the places where coolant lives, just ain't getting around. I was looking online for a new water pump. I thought that had to be the problem.

Fortunately I was interrupted while heating the engine up without the cap on the fill tank. This is not something you normally do on a pressurized dexcool system. The heated coolant belched out about a half cup on the ground when hot (over 212-220F). I turned the car off to go make some copies for somebody and by the time I got back the reservoir was almost empty! The hot engine without the cap on had cooled and sucked a half tank back into the engine. This is what's called "burping the system" where the coolant sort of gets vapor locked if you don't get rid of this air. I am guessing the water pump is spinning in trapped air. I Filled the coolant back up to the mark and everything works fine once again! The only additional thing I did was keep a close eye on the coolant level over the next couple of weeks - adding premixed coolant if it needed it. Be aware, do not add just water! Straight water added to the system will alter the mix's boiling point and cause problems for your car. Always add the 50/50 mix.