1. A cooling system works by sending a liquid coolant through passages in the engine block and heads. 2. As the coolant flows through these passages, it picks up heat from the engine. 3. The heated coolant then passes through a rubber hose to the top inlet of the radiator in front of the car.4. The coolant flows down through the thin tubes in the radiator; the hot coolant is cooled by the air stream entering the engine compartment from the grill in front of the car.