We don't have a distributor. Hosing down the engine is only bad if it's done when the engine is hot and you hit it with cold water. With the exception of some wiring harnesses (which are all moisture "resistent" types), hosing down our engines when cold, with hot water is a good way to clean it. Of course, if you have a CAI with an open filter when the hood is up, wrapping the filter with plastic is a given. There is nothing else under the hood that can't get wet. Just don't take a high pressure nozzle to it.

 

I use a hose to rinse my engine off ~once every other month after a good detailing.