my /6 runs hot

I have ran in to issues where the suction radiator hose had separated internally. The pump would suck the hose to nearly a closed off position but you couldn't tell it by simply looking at the hose. Also if you have access to an infrared thermometer you could get the temperature of different spots and possibly locate where the problem is. Plugged up radiator is also a possibility. Could the thermostat in upside down?