I have read a couple of the previous questions about heaters in this model. I recently had the motor rebuilt and now, no heat, only cold air gets blown. I have checked everything I know. The radiator, water pump, hoses, and heater core. While the engine is running, the heater hose going to the heater core is hot and has pressure. But the hose coming from the core is cool. So does that mean the core is stopped up? Also, the coolant temp guage is not registering. Could all of this mean the water pump is not circulating properly? Any advise is appreciated.