The engine bay is a delicate place to clean and at the same time one of the most subjected to acumulate dirt, oils and dust.
To clean this area we use a good degreaser (without acid) with the help of a brush. After cleaning each zone without letting it dry, rinse it with a string/spray of water in small amount.
After cleaning, it should be dryed with a clean toal. In the end it should be protected with the help of a dressing or motor lack.