I pressure wash my equipment on a regular basis. On a cool engine, spray some Simple Green or some other relatively non industrial cleaner and let sit for a few minutes. Also, if you see any delicate areas that you think MAY cause damage by water infiltration, either cover them up or stay away from them. Remember to, at the very least, shroud your alternator in a plastic bag and tie wraps before doing any cleaning. Stay away from the radiator fins, and make sure all of the dipsticks and fill caps are securely tightened. I use a 3000 psi pressure washer, and stay a minimum of 20 inches away from what I am cleaning in the engine compartment. Things always come out looking great. I have been pressure washing engine compartments on all types of vehicles and equipment for 30 years, and I have never had any negative results, never any damage or failures due to water infiltration. A little common sense goes a long way, but my opinion is basically that...."If it cant take a little water, it has no business on a tractor, car, truck, ATV etc."...Just my 5 cents worth.