About a month ago my daughters 2003 Civic reached 100K miles and we had pur family's long trusted mechanic do the 100K timing belt, spark plugs and water pump replacement.
A couple of weeks later the car's temp gage rapidly soared up during city driving. Not wishing to take any chances, daughter called AAA and had her Civic towed back to the mechanic who'd done the 100K maintenance.
Our mechanic test drove it and told me that he couldn't get it to overheat. There was plenty of coolent in the system and while we discussed it on the phone I suggested that maybe the thermostat was flakey and asked him to replace it. He did that.
The car didn't overheat again for about 8 days, but while on a road trip the temp gage soared up while on the highway. She limped the car to a repair shop where the mechanic there diagnosed it as a failed cooling fan temperature sensor and replaced the sensor.
The car is still intermittantly rapidly overheating as indicated by the temp gage. I showed her how to stop the car, open the hood, and see if the cooling fan was running. She reports that it is.
I suppose that it could be nothing more than a defect in the temp gage system, and the engine isn't really overheating, but the fact that the gage sweeps up over a period of a minute or so and doesn't snap to a new reading has me doubting that.
At this point my best guess is that something is causing the coolant circulation to quit. My limited experience with Civics has me remembering that the water pump is driven off the smooth side of the timing belt, so perhaps there isn't enough tension in the belt to drive the water pump properly and when the belt slips the pump stalls?
Thanks for any leads guys,
Jeff