Around here, if you go to a used car lot and look at the engine compartments of the cars, they always look new. That means they wash the engines all the time and they always come out OK.
Last year I did the engine in my Intrepid for the first time ever. I borrowed a high pressure washer with the soap dispenser attachment. I used Simple Green detergent(really good stuff) and I used way too much. I turned the thing on, aimed it at the engine and pulled the trigger. Within seconds the entire engine compartment was a giant white foam. Foam puffing up to the underside of the open hood, pouring over the fenders, foam puffing out from underneath the car, foam everywhere. I was shocked. I figured, "what the he**, it's too late now", so I blasted away some more and then let it sit for about 15 minutes. I then blasted with clear water. The entire driveway was foam right down to the street. But the engine and compartment looked like it had come right from from the factory - absolutely like new !
I towel dried all the standing water from the nooks and crannies and then let it sit for an hour to dry out. It was a hot summer day and the engine had been just warm before I started cleaning. After an hour, I turned the key and it started right up like it always does. I was really surprised.
Next time I definitely will cover some of the electrical stuff. I think I just got lucky the first time around.
Phil