Actually the hose going to the water pump is the return hose. The pressure comes from in back of the thermostat. With the engine warmed up & the fan on high grab the hoses. They should be about the same temp. & you should not be able to hold on to them over 2-3 seconds. If the return hose is cooler the core is plugged up. If neither one is real hot the therm. is bad.
