It's real easy. Get access to a pressure washer. Some self serve carwashes don't allow engine cleaning, but who's gonna stop you late at night? LEAVE ENGINE RUNNING. Spray engine down with Simple Green. Let sit a minute, and rinse with pressure washer, keeping water away from electricals and intake, at least don't keep the spray on them. Let air dry. When dry, spray engine down with Armor All. Let air dry. You may want to cover your fenders with towels. The chemical I used to do this when I detailed left streaks in the finish (wasn't simple green). Wasn't a problem as the car would then be buffed, taking the streaks out.
