If the pressure in the cooling system exceeds the maximum valve, the radiator cap ________.

If the pressure in the cooling system exceeds the maximum valve, the radiator cap ________.

• A. Releases coolant into the overflow hose
• B. Diverts the coolant to the expansion tank
• C. Overflows directly from the radiator
• D. Engages a secondary relief valve

Answer: (B)

When the cooling system is heated, it tries to expand, and the radiator cap is designed to hold the system under pressure while guiding that excess coolant somewhere safe. The cap has a relief path that opens at a set pressure and pushes the coolant into the expansion (overflow) tank rather than letting it spill out onto the ground. This keeps the system closed and allows coolant to be stored for later return to the radiator as it cools. So, when the pressure reaches the cap’s limit, coolant is diverted to the expansion tank. The expansion tank stores the extra coolant and, as the engine cools and pressure drops, coolant is drawn back into the radiator to maintain proper levels. The other options would either vent coolant directly to the environment, which isn’t how a modern closed system operates, or imply a separate valve that isn’t part of a standard radiator cap.

When the cooling system is heated, it tries to expand, and the radiator cap is designed to hold the system under pressure while guiding that excess coolant somewhere safe. The cap has a relief path that opens at a set pressure and pushes the coolant into the expansion (overflow) tank rather than letting it spill out onto the ground. This keeps the system closed and allows coolant to be stored for later return to the radiator as it cools.

So, when the pressure reaches the cap’s limit, coolant is diverted to the expansion tank. The expansion tank stores the extra coolant and, as the engine cools and pressure drops, coolant is drawn back into the radiator to maintain proper levels. The other options would either vent coolant directly to the environment, which isn’t how a modern closed system operates, or imply a separate valve that isn’t part of a standard radiator cap.