In cooling system pressurization, which statement is correct?

• A. Pressurization enables coolant to remove more heat
• B. Pressurization keeps coolant from boiling
• C. Pressurization reduces system weight
• D. Pressurization increases flow rate

Answer: (B)

Pressure in a cooling system keeps the coolant from boiling by raising its boiling point. As the engine heats up, the coolant would reach a temperature where it would boil if the system were not pressurized. By maintaining pressure, the liquid’s boiling point increases, so it stays in liquid form across the operating temperature range. Liquid coolant conducts and transfers heat more effectively than steam, so keeping it from boiling ensures consistent heat removal and avoids vapor pockets that would insulation and reduce cooling efficiency. The radiator cap or similar pressure mechanism is what maintains that higher pressure, enabling the system to operate safely at higher temperatures. This is the key reason pressurization is essential. It does not inherently make the flow rate higher or reduce the system’s weight; those effects aren’t the primary role of pressurization.