i detail cars at carmax and one step is engine wash. and yes it will be fine just make sure it is cool. i use engine cleaner (carmax stuff) and get an engine brush. then rinse with power or preasure washer just stand with in 2-4 feet away and try to avoid fuse and parts where water can get in the spark plugs and coils. then let it dry. after that everything went fine. i did 2 evo's already and non had any problems.