What is an important safety precaution regarding the radiator cap?

An important safety precaution regarding the radiator cap is that it should not be removed when the coolant is hot. When the engine has been running, the coolant temperature can rise significantly, leading to increased pressure within the cooling system. Removing the radiator cap while the coolant is still hot can cause hot coolant to spray out, which poses a serious risk of injury through burns or scalds.

It is essential to allow the engine to cool down before attempting to remove the cap, ensuring that the pressure has decreased and the risk of injury is minimized. This understanding emphasizes the need for safety when performing maintenance on a vehicle's cooling system.