Well you don't want to do it while the engine is running....that would cause problems. But generally speaking, yes, it's perfectly fine to pressure wash an engine. It's quite common to do. The key is just knowing what you're doing and avoiding certain things. Spark plug boots can be ripped, so can other sensitive rubber seals that would be exposed to the pressure. You won't hurt the belt, or pulleys or anything else doing it. Oh, and DON'T spray inside the intake (should be common sense, but you know that goes...)

Well, I will say this I have worked on cars for more then 30 years. I power wash my engine about twice a year and have NEVER had a issue

absolutely not!!!

Your engine has very sensitive equipment, such as your sensors, that could be damaged by the intense pressure of that washer.

Not only that but any grounding or wiring that could be damaged as well.

Steam clean the engine instead.

And to the moron who said it was okay to pressure wash your engine, never-ever take your car into him again. To the nay-sayers who say "ITS A GOOD IDEA" I'm not the only one who says its BAD: http://forums.anandtech.com/showthread.p...

I have been okay most of the time and did expensive damage once: the fuel injector connector boots were torn and the connectors corroded. $2000 for an engine harness....

It looks nice but does not help at all (it helps the engine BREATHE?), might hurt. Steam is a much better idea if you are going to clean the engine bay.

Do not freaking do that.