[Tachyon]

What type of material are you looking to remove from your engine?

For mud and the like I use Tide in a spraying container attached to a garden hose + lots of water pressure.

For major grease/oil buildup, the most effective method that I’ve used is to use gas. Fill a bucket with gas, then, using a large bristle paint brush, apply gasoline to the top of the grease zones and watch it fall off the engine / bay. Immediately after, spray with water.

If you are worried about the alternator just throw a plastic bag over it, however, I personally haven’t had a problem with it shorting out. (after all, the alternator gets saturated with moisture when driving in the rain)