a "How to " on Cleaning my Engine
if it is on a stand or partially taken apart then any opening should be sealed off.
If it is outside of the car then i like to use brake parts cleaner especially when I know I am going to touch up the paint. it is pretty agressive and evaporates away.
Inside I usually just wipe it down with a rag unless there is more than just minor problems to clean, I know some people that will hose them off with something like simplegreen to remove the grease and dirt. I think this would be ok as long as you don't use a real high pressure wash that could shoot into seals etc.
Good luck


