I see people do it but at the same time I wonder if it's really a good thing. I have cleaned my engine before using engine degreaser and hosing parts of the engine VERY CAREFULLY. Usually I will cover the distro, rubber parts that might be affected by the degreasing agent, and the brake fluid resv. In tight places, I will use a cup or a watering can for precision rinsing; a garden hose would just spray water everywhere, especially when you are just doing it by yourself and have to turn on the water and then run quickly to the hose and bring it over to the location usually spraying water in unnecessary places. I can twist the hose nozzle so that it will not spray water, but when I loosen it a jet of water shoots out. But that's not a big deal because I can aim the jet of water down and then once all the pressure is gone I will bring the trickling water to the location. I see people sometimes hosing their engine bay with wild abandon, as if they were washing the exterior of their car. Yesterday I took off the belly pan and sprayed some GUNK engine cleaner and hosed it down. I was careful about shooting water at high pressure or even spraying water anywhere. I tried to avoid the belts and pulleys and any wire connections. I carefully aimed the hose in places that were sprayed with GUNK. (GUNK recommends that minimal amount of water be used anyway--environmental thing, I guess.) Am I being too careful? Can I just blast high pressure water at every nook and cranny and give the engine a good cleaning?

BTW, It feels good knowing that I have a grime-free belly pan! I gave it a good degreasing and rinsed it with blasts of water. I can't believe anyone would drive their brick without a pan. So easy for debris to get inside the engine bay! The belts look so exposed without it. It's weird, The engine bay doesn't look complete without the pan.