I've noticed that quite a few car washes around are offering self-service engine bay power washes. Can any damage be done to my car this way? Anyone else used them? Results?

I use the engine degreaser and rinse at my local DIY wash. It's a decent place w/ horse hair brushes and such. I use the pressure rinse, but I hold it far enough away from the parts so that I'm not putting a lot of pressurized water on anything. I just sort of fan side to side about 3' away until the degreaser sort of naturally rinses off instead of blasting it off. Yeah it takes longer, but I don't really want to pressure wash my electrical stuff.

Try using Simple Green....spray it all over the engine compartment...then aggitate the really dirty stuff with a brush and spray it with a hose.....works very well with no excessive pressure

No chance of it cracking the block if the engines hot?