I now try to avoid the mud when possible. You just can?t get it out of the radiator fins once it has dried in there.
That said; I would never ?power wash? any part of the inside or under the hood of the truck. Pressure washing any thing risks blowing apart some connection or bending something out of shape. Years ago a guy I was wheeling with tried to pressure wash the mud out of his radiator, bent most of the fins and over heated on the way home.
When I did venture in the mud and needed to clean up I would cover any electrical connections with dielectric grease. It is best to do this before going into the mud but if you have not I?d clean the connections by hand and then cover them with the grease. I cover the bunch of electrical connections on top of my 1st gen with a rag before spraying or rinsing anything near them.
Then I?d spray Simple Green on the parts of the COLD engine I wanted to clean (not the whole thing) and let it sit for a bit. If the mud was caked on I?d loosen it up with a bit of water, a soft brush and/or wet rag. Then using a hose with NO NOZZLE and MINIMUM PRESURE let the cold water wash over the mess still taking care not to get the full weight of the water on any electrical connections. Even when you take this much care there will still be a chance of fucking something up so my advice is to try and keep the need for engine cleaning to a minimum (stay out of the mud my friend, stay out of the mud
).