When you say "engine cleaning stuff", I assumed that you meant spray degreaser kinda stuff for cleaning the outside of the motor.

Engines should be wiped off with rag, maybe a little all purpose cleaner (like Fantastic, although I don't buy the name brand), maybe a little "purple stuff" (new liquid degreaser that works great but can mark aluminum, Castrol sells it, but Napa has a "copy"), but NEVER pressure washers or copious soap and water.

Every Sunday morning I go to the local coin operated wash rack, which attracts 50+ nice cars. Nearly every time someone decides to "clean" their engine, going full force with the pressure gun. 90% of the time, the car doesn't start afterwards...

-David