So I'm not too sure about the answer to this question: explain why it is advisable to add water to an overheated automobile engine only slowly, and only with the engine running? So if something is overheating, it makes sense to want to cool it. Since the water's temperature is less than that of the engine, pouring it on will lower the temperature of the engine. But what about thermal equilibrium, and engines in particular, makes it risky to pour in water quickly? Will too much water mean that the liquid will hit the engine without being boiled, thus damaging the engine? And what about an engine running makes it advisable? Is it because it keeps its overheating temperature constant?