I will second the cleaning of the engine..... with adding some advice.
Use simple green, not the store aerosol degreaser.
Only spray a cool motor. Dont douse the electrical bits. Minimal water is ok.
Beg and borrow someones pressure washer, even a cheap one works wonders.
Try to set up the car in a sunny place.... so with the hood open the sun can helpdry things out.
Wait a couple hrs before starting it again.
WD-40 is your friend.... its stands for water displacement. As it is drying out spray the electricals with it.... also ok for the ducts, hoses, & raw metal.
Leaves a nice finish. .... keep it off belts, pulleys, and pulley bearings.
Find a good oil spray.... you might need it for some of the pully bearings....squeek..... don't use the wd, its not thick enough.

Keep all this stuff off the exterior paint. I usually polish the rest of the car as I wait to start it.
FYI- I just did the head gasket on my 300SE.... it sucks... pay someone to do it if needed.
This is a hobby for me, to keep my sanity from the weekday senior commercial banker thingy.
Ken