I had an intermittant indication of overheating with my Optima. I tried everything to isolate the problem: new water-pump, new thermostat, radiator flush. However, when the needle approached red, and I turned off and turned on the engine again, it would show normal. This turned out to be an electrical problem, and was eventually isolated to (you're not going to believe this) A LOOSE NEGATIVE BATTERY CABLE!
Monday, July 14th, 2008 AT 10:20 AM