Mating Surface Prep
Once you have cleaned off as much as you can with a gasket scraper (or another method for other surfaces), go over the mating surface with a rag that has a cleaner on it that will not damage the surface you are working on. In this case a strong degreaser that can also breakdown sealants will help remove the loosened gunk. Brake cleaner or mineral spirits will do the trick and will evaporate without leaving any residue that will need to be cleaned off. When using these chemicals, be sure to stay safe. The vapors from these are poisonous. I wear chemical resistant gloves such as nitrile or chemical handling gloves, as well as a respirator with the appropriate cartridges, and eye protection. Here you can see the mating surface already starting to look better, but it's not done yet, there is still corrosion, stubborn, stuck-on gasket material, and sealant.
Prep Procedure Image Gallery | Image 3 of 8