1990 Toyota truck, no heat, upper radiator hose hot, lower hose cold, new radiator and heater core?
Truck has a new thermostat. How can the upper radiator hose be hot and the lower hose be cold if coolant is moving through the system? If the coolant is not moving thru, then why doesn't the engine overheat.
the upper hose is hot because the water is coming from the hot Eng. the bottom hose is cold because the hot water is being cooled throw the radiator fins before it gos back in to the Eng. that's why they all it a cooling system, to cool the the Eng.
