My puke bottle has fouled the front of the motor with an oily buildup. Bought the truck a year ago and I bet it's never been emptied or serviced. Is there any caution about using chemical cleaners and a power washer on the engine? Obviously I know not to do it hot. Any area of the engine to be careful about high pressure water cleaning?

 

Try to stay away from electrical components, connectors, and airbox.

 

and from the alternator that could be a real big mess. Unless you need a new one then go for it !!!

 

I have had excellent results with WAB engine and chassis degreaser and a pressure washer. Just don't breath while you're spraying it on, hot damn! But yeah, stuff works awesome. I only used the pressure washer because of the heat, I had the pressure all the way down so it was more of a steam rinse than anything. Years of a leaking valve cover, crank seal and steering pump and the fan blowing that crap all over the bay had it looking like a real mudball. I don't think I let that stuff soak even five minutes before I hosed it off, and it came so clean so easy it blew my mind.
But yeah, what they said. Especially if you're pressurized, don't try to blast anything that clearly isn't intended to get wet. I actually hit my alternator too, quickly, and didn't have any issues... yet.