Fun fact: When water freezes, it expands by almost 10 percent. Not-so-fun fact: If your raw-water cooling system holds, say, 10 quarts of water, when it freezes, there will suddenly be an extra quart inside under great pressure, with nowhere to go. It’s enough pressure to destroy a manifold, wreck a refrigerator, and even crack an engine block like an eggshell. The key, then, is to get water out of places where it will cause damage when it freezes.