The degreasers will not harm any components but protect any electrical stuff like the distributor with a plastic bag as they dont like water and go for it. I have just degreased the engine bay on my Sons Subaru Impreza, used a large aerosol and small brush and it cleaned it up a treat.
Mopped up some standing water and it started first time with no problems. I only use a garden hose as a pressure washer is to powerful.