A water-cooled engine typically has a _______ coolant pump

• A. Diaphragm
• B. Gear pump
• C. Centrifugal
• D. Positive displacement

Answer: (C)

A centrifugal pump is used for a water-cooled engine cooling system. It works with an impeller that spins and throws coolant outward, creating flow from the radiator through the engine and back to the radiator. This design provides a large volume of coolant at relatively low pressure, which matches the cooling loop’s needs and increases flow as engine speed rises. It’s simple, rugged, and inexpensive, and it’s driven by the engine via a belt and pulley. Diaphragm pumps and gear pumps aren’t typical for this role—the former is usually for specific fluids or niche applications, and the latter is a positive-displacement design that produces higher pressure and is more common in oil or hydraulic systems.