I really REALLY need help, because at this point, we're stumped. We have an 03 CTS that had to have an engine rebuild. Now, I have a problem with the car overheating. I've replaced the thermostat, water pump, head gaskets, oil cooler, used the cap off my reservoir (I have the exact same car with no issues) and still having the car over heat to 270. I've flushed the radiator numerous times and still don't know whats going on. I ran a blue dye test and there is no exhaust in the reservoir. The fans are coming on and work. I'm not sure what else to do or check.