Just go easy with the hose, and you should be OK. All engines are made to injest water in the engine comparment, else everything would die when it rains, and you go splashing through puddles.
I would recommend that no one steam clean their engines. I've known quite a few mechanics that spent days, and months trying to figure out all sorts of strange problems with customers cars, only for it to come down to corrided connectors in the engine compartment. Steam cleaning forces moisture into place that splashing water would not get to. Everytime it was in all the wiring connectors, like the fuel injectors, or any mid-wire connectors.