What is the appropriate action regarding the radiator cap if the engine overheats?

When an engine overheats, it is vital to maintain the integrity of the cooling system, and leaving the radiator cap closed is the appropriate action. The radiator cap is designed to maintain pressure in the cooling system, which raises the boiling point of the coolant. If the engine is overheating, the system is likely under extreme pressure and any attempt to open the cap could result in hot coolant or steam being expelled, which poses a serious safety risk.

Keeping the cap closed helps to contain the pressure and prevents coolant from splashing out. It also allows for a controlled environment for the coolant to work more effectively, should the engine cool down. Once the engine has cooled, and it is safe to check the coolant levels or inspect the system, that is when one can safely assess any needed actions regarding coolant or the radiator cap itself. This careful approach is crucial for ensuring personal safety and effective management of the overheating issue.

In contrast, opening the radiator cap during an overheat situation can lead to burns from steam or hot coolant, while checking coolant levels or replacing the cap can wait until the engine has returned to a safe temperature.