jhawkr

I just spray mine off at the car wash and then use the spot free rinse. I never need any soap/cleaner. Cars are designed to operate with water going all over the place when driving in the rain. I've never had a problem.

Rudolph Hucker

do as i do.
never ever go out in the rain..my engine bay is like new still after 8 years.

CMcNam

Pretty much how I feel. Just as a precaution, I cover the intake filter, battery, and fuse box. I've been shocked with the battery more than I care to think about (ummm...don't ask...basically amounts to 'I'm an idiot'), so I don't play around with electricity. Spray it down with Simple Green (as others have said, don't do it too long, I completely ruined my manifold cover, the cheap plastic one that says "Ford" on it with the running pony), scrub with a plastic brush where necessary, and hose it off. I prefer to do it when it's all cool, I don't like the idea of spraying off warm or hot metal. I touch up the plastic bits with some "Back To Black" cleaner stuff I have and I'm all done.

I don't have any evidence to back up my precautions, I just know that my engine bay is clean and the car still runs great (and I haven't been shocked).