I replaced my thermostat, but my car still seems to be heating up and then not being able to cool itself. Any ideas? The new thermostat is working very well, as I went to remove it altogethor and warm water was trickling through it, so I left it in. Could it be a water pump that needs replaced? It's a salvage car but has driven fine for a year and a half, and the CEL has been on every day since I got it. In this heat (So Cal) I can't even drive 5 miles to get a computer on it to see what the errors might be. Maybe if I drive it in the middle of the night. To Kraggen.