It all depends on how badly soiled it is under the hood as to what the first steps are to be. If it is really bad with grease and oil , you need to start with a degreaser product of some kind first. If it was like my truck and was just on the heavy dusty side (I wash it down about every time that i wash the truck) it will not be all that difficult at all. What i do is (here goes my tricks
) take a can of no touch tire foam and lightly spray under the hood being careful of the K&N filter and anywhere else that i think should not get wet by such a product paying more attention to the more dirty spots. I do this before i leave to go to the car wash, this allows the tire foam to loosen all the dirt and crud so that when i am at the car wash and once i am done soaping the truck and am ready to rinse not with water but with wax (i never rinse with water cause imo it is a wasted step) i open the hood and give it a good rinse off under there, i use wax and not rinse cause the wax allows the excess water to run off easily. After I get back home, out comes the Armour all and an applicator pad, and if you spend the time that is needed to do the job right the end result will be worth the time. I just did the engine compartment of my 2000 Silverado with just over 91,000 km's on it and it looks like a brand new truck under there but don't take my word for it , judge for your selves.
