Just a thought. I think flushing your cooling system is a good idea to replace the old worn out coolant (it does wear out I'm told), but in my experience, flushing won't cure most overheating problems, and I don't seem to get much of any curd out of the system when I do it.
Over the years, I've had cars that would overheat and the causes were usually bad thermostats, or ignition timing too retarded (gas engines), and radiators that needed to be "rodded" out to remove the insulting layer of scale.
The cars that needed the radiators rodded did have their systems flushed out periodically, but still plugged up their radiators.
Maybe Bill has more insight into my observations.