[kosd]

I cover my alternator with a bag then spray diluted meguiars all purpose cleaner all around the areas I want to clean (cold engine only) and agitate with a boars hair brush. I use a garden hose throttled to very low pressure to rinse. I usually do this once, maybe twice a year and it has worked well. I dry with a microfiber towel on the areas I can reach. In one vehicle where I had a previous oil leak, I used brake clean to clean the affected areas before doing my normal engine bay detail.

I would not use a pressure washer. In my opinion, less is more when detailing areas with the potential to damage electronics.