lower radior hose
2 Answers
The upper radiator hose is where the hot coolant enters the radiator from the engine. It cycles through the radiator, cooling as it goes. When it reaches the bottom, it moves out of the radiator through the lower hose and back into the engine to start the cycle once more...
The normal flow is from the lower hose to the water pump, through the cooling passages in the engine, and back through the thermostat to the upper hose and then to the radiator.