Heres what i do for a clean engine.
Materials-
-Engine Brite Spray, any auto store has.
-The Works Cleaner-Can be found at grocery stores, kmart, big lots, etc etc
-Small wire brush or hard bristle tooth brush.
-Rags
-Pressure washer/strong hose
-Black Magic Tire shine
- Meguiars Hot rims Rim Spray.
-Sponge
1. Soak your engine in the Engine Brite Foam. Let sit for twenty minutes or so.
2.Spray the engine down with pressure washer. Be sure to get all the foam off.
3. Left over residue can be taken off the Works cleaner, I empty mine into a spray bottle. Much easier to use that way. Spray it onto tough areas and lit it sit for ten minutes.
4. Come back to them with your wire brush and gently brush away grime, scaling,etc. Do this to any metal parts you see built up with scum. This can take a long time depending on how bad your engine is, But take your time and it will come out beautiful.
5.Now spray your engine down once more to rid of the scum left over from brushing.
6.Take your tire shine and soak the plastic parts in it, Allow to sit for five minutes.
7. While your waiting, soak your metal parts you just brushed down with the Rim Cleaner/Polish.
8.Come back to them with just a rough sponge and use some elbow grease and buff the chemicals into the plastic and metal, Wipe away any excess with rags.
Admire your beautiful engine.
Mine comes out great every time. Just my way though.