Texas CDL General Knowledge Practice Exam

When a coolant container is part of a pressurized system, what is true about checking the coolant level?

1. A. Check only when engine is cold

2. B. Check only when engine is hot

3. C. You can check the coolant level of a hot engine

4. D. Never check the coolant level

The correct answer is: C. You can check the coolant level of a hot engine

When dealing with a pressurized coolant system, the correct approach for checking the coolant level is to allow the engine to cool down and check when it is cold. This is vital because when the engine is hot, the coolant and the system itself are under pressure. Opening a hot coolant container can be dangerous due to the risk of hot coolant erupting from the reservoir as the pressure is released. In most situations, it is advisable to check the coolant level when the engine is cold. However, if you were to check the coolant level when the engine is hot, you must exercise extreme caution to avoid being injured by the hot coolant or steam that may escape. While checking the coolant level is generally not recommended when the engine is hot, the choice stating that you can check the coolant level of a hot engine suggests that it is possible—albeit with risks involved. Proper procedures and safety precautions should always be followed to prevent accidents.