Which ever way you decide to clean your engine, read and follow the instructions!!! Last week I went to my neighbors to replace his water pump. I opened up the hood and smelled a odor similar to paint. the engine itself looked like it had a thick film of dirty oil on it. After I finished up, my neighbor came back from work, looked under the hood and said, "Damn degreaser!!! that crap doesn't work!!!" I asked him if he had hosed it down with water. he replied "Hose it down? Hu?" 'Nuff said right?! to this day he hasn't done it! Long story short, don't be a schmuck, read the instructions!!!

 

I don't think washing the engine bay is bad, just be careful of hitting wires with to much water. And I would avoid high pressure if your gonna use a pressure washer.