I'm cleaning my engine bay today and installing a gun holster under my seat. What do you guys use to clean your engine bay, a de-greaser or just an all purpose cleaner?
Depends how dirty it is and the components you want to focus on cleaning. Before any engine bay detail it recommended you cover or remove any open air intake and battery terminals.
I actually just did mine yesterday. I removed my intake filter and breather filter and plugged both holes with a rag. Then I rinsed any loose dirt off with the hose set to the mist setting. Then I took my sponge I use on the lower portion of the car and leftover soap after washing and washed all the components the best I could, being careful not to soak the engine bay that much. Then I rinsed with the hose again on the mist setting (this works really well without using too much water and soaking everything.
Today I am going to remove the engine cover, the hood insulation and hose them out and wash. I will then detail the engine bay with quick detailer or use the interior vinyl detail spray on the plastics.
Next week I will be doing my GF's Forester engine bay which is disgusting and will post a write up.
TLDR:
Mild soap should be all you need unless it is very greasy and dirty, then I would recommend a degreaser diluted with water. Use as little water as possible in the engine bay to not soak it too much. Will dry faster and protects the other components that really shouldnt be getting that wet.