Which of the following is a method to cool an overheated engine?

Opening the engine cooler while pumping is an effective method to cool an overheated engine because it allows for a more efficient heat exchange. When the engine operates, it generates heat, and the coolant absorbs this heat to maintain optimal operating temperatures. By opening the engine cooler, the flow of coolant is increased, which facilitates better cooling by dissipating the excessive heat more effectively.

This approach is particularly useful during operations when the engine is under heavy load, such as during pumping, where the risk of overheating is heightened. Active cooling through the engine cooler can prevent engine damage and maintain operational efficiency.

While other choices may seem relevant, they do not directly contribute to cooling the engine in an effective manner. Increasing engine speed can actually lead to even more heat generation, turning off the air conditioner does not affect engine temperature significantly under pumping conditions, and switching fuel types is unlikely to address an overheating issue in a timely manner during operation.