How To Clean Your Engine . . . If you can, hook up to a hot-water tap. It will do an even better job.
Many car washes have equipment specifically for cleaning engines.
Clean the engine first, and wash the vehicle afterward, making sure all overspray of the degreaser is removed. All degreasers will remove wax, and some can damage paint. . There are many reasons why it is important to clean the engine and its surroundings routinely. A clean and tidy engine compartment makes it much easier to detect oil and fluid leaks, damaged or worn drive belts and rust or battery corrosion before they lead to more serious damage. And if things really get out of hand, the dirt could provide fuel for an engine fire.