After engine block is hot tanked and dry, we have the option of Soda Blasting.  This makes the aluminum look brand new, and has the best surface finish.  We use proper procedures to prevent media from entering the water jackets, along with oil galleys.  Lastly, we include a Submersible Jet Flush, to dissolve of any remaining blast media.   We take pride in our cleaning procedures after soda media is used, as all media dissolved,  flushed, and blown out to ensure no media can risk your project.