GM250: Never apply any degreasers/cleaners to a hot engine unless they specficially say to do so.
Always test any cleaners you plan to use on a spot first, many will fade or peel paint on the engine or firewall so BE CAREFUL and always test anything the first time.
jf: Power washing is good but it tends to damage some things due to the extreme pressure. Power washers are good for the undercarriage, tranny, and that heavy caked on stuff, but the engine you need to be careful and avoid squirting any water into the carb or electrical.
