Don't wash it if your engine has been running more than 15 minutes. You'll crack a block or head really quick. If the engine is at operating temp don't spray directly at the engine. Keep a slight wave motion. Don't use GUNK on a HOT ENGINE!! The fumes can serious damage to your lungs, eyes and nose!
Use a car wash with hot water.
I spray an engine cleaner in the bay then let it sit for a while. Then I go wash it off.
