Will soap and water hurt anything under the hood? My oil filler cap came off and I got a LOT of new oil everywhere...in addition to the old built up oil. I want to use liquid Dawn and a water hose to degrease everything. Will the water and soap hurt anything? The alternator is the biggest thing that worries me.
I used to own a C4 with the Optispark and a water hose under the hood was a major no no so I thought I had better ask first.

 

Cover the intake and you'll be fine as long as your distributor cap seal is good. For an extra precaution, cover the distributor and the area where the spark plugs are. Use saran wrap.

Don't use soap and water, just buy a $5 bottle of engine degreaser from the auto parts store. It works WAY better. With the engine warm (not hot) and turned off, spray it on and let it soak for 5 minutes and then spray it off. Try not to spray the alternator as much as possible and you'll be fine.

 

dito...
simply green is some great stuff! i used a pressure washer tho.

only a few things ive done when i cleaned mine..... best to put a bag on the air filter and tie it best you can or use some tape, also wrap some bags around the main wire harness plugs. drivers and passenger side harnesses. and mainly the distributor cap really good. IF IN DOUBT about geting water into the cap then after your done remove the cap and let it air out overnight.

and if you have a cheap ebay air intake be sure to remove the air intake because degreaser (at least on mine) clouded the chrome finish very fast and looked horrible!
i used a largest bottle of simple green they had at autozone! i sprayed it on thick over the whole engine bay let it sit 5 mins and resprayed it again let sit another 5mins and repeated again. then sprayed it off!
then i removed all my bags and tape and then i let it sit afew hours before i tried to fire it up. no problems with mine.

 

Thanks for the responses guys. I was thinking along the lines of bagging the alternator. Had not thought about the distributor or wiring harness though.

 

i didnt bag my alternator. its fine. its sealed very good already and since its far down under other motor parts you wont get to much pressure directly on it anyways. i didnt cover mine up and it was fine.