Contour Enthusiasts Group Archives Forums General Troubleshooting Overheat question!

Last night its busy as hell at my dominos store in kingston, one of my drivers cars break down so i have to take a double delivery, fire up the car drive to the first one and shut it off, come back, fire it back up fly out to the next one and left it running out front, when i come back all i can smell is burning coolant, but i didn't look at my temp gauge till my check engine light came on and saw that it was maxed out, i shut it off and coasted back to the store. The coolant was boiling but not too badly. So everything i know about cars and there intricate workings told me that its just the thermostat cause the heater is blowing cold air even cranked up and on the hottest temperature. Canadian Tire changes the thermostat and its still overheating at the store so they say they will check the headgaskets, now i never saw any white out the exhaust pipe it still had all its power, could this be a sign of a broken water pump impeller, or something worse?