What type of car/truck motor are you detailing? Some are more sensitive to where water gets and can cause problems. I've done more motors than I care to admit lol. The biggest thing is don't spray water into connectors or intakes. Use common sense.
Always clean a cool motor. Some people bag the air intake and altenator, I don't, but I do make sure and used compressed air/master blaster and blow out everything before I start the car. Don't let water sit epecailly on plug/coil packs. Ford v-8s are notorious for getting water down the coil tube and causing a missfire.
First I spray everything down with a pressure washer and knock off as much gunk as I can. This makes it so the degreaser has less to break down. Then I liberaly apply Degreaser to everything. Make sure its safe for plastics. (I use Automagic Red Hot) I don't know what AG sells for degreasers so I can't comment. I let the DG sit on everything then hit up what I can with my Daytona Speed Brush and Green Brissel brush and knock off and work the DG in. Then Ill spray everything really well with my pressure washer and get all the DG off.
After I see that I have everything clean, Ill blow out everything with air. I spend a lot of time doing this because it makes a difference. After everything is dry, I take my Tornador and some dressing watered down (non silicone based, not good for electric connectors) and spray down my plastics,hoses,walls, what have you. Then I'll take compressed air again and blow the dressing around and then wipe stuff down with a junky MF to make sure the dressing spreads out nicely.
Like I said, use common sense and don't force water where it shouldn't go, use a quality degreaser & brush, and BLOW EVERYTHING OUT WITH AIR!
Good Luck, Let me know if I can help any more!