Well I'm not worried about flooding, but my friend actually cracked his engine block because he had a hole in his hood (rusted out), and water dripped on the engine while it was still hot, but not running. Sort of similar to how pans warp if you put them under water while still hot.
EDIT: I live in Hawaii, there are times when it can be raining on half a building, but not the other half. And sometimes we get some pretty intense rain. Which is why I am wondering if there are problems with the engine getting water on it, particularly while still hot.