CDL General Knowledge Practice Test

Removing the radiator cap when the engine is still warm, even if it does not appear to be overheated, can be very dangerous. The cooling system is under pressure, and opening the radiator cap can cause hot coolant to spray out, potentially leading to severe burns or injuries.

Even if the engine doesn't seem to be overheating, the coolant can still be at a high temperature and under pressure. It's important to wait for the engine to cool down completely before attempting to remove the radiator cap. This ensures that any built-up pressure is released safely and minimizes the risk of injury from escaping steam or hot fluids.

Some alternatives, such as waiting for the car to be off for a while or taking precautions like wearing gloves, do not eliminate the inherent risks associated with releasing the pressure in a heated cooling system. Always prioritize safety by allowing proper cool-down time before opening the radiator.