I've never had good results with a off-the-shelf chemical cleaning with these or other (BMW motorcycle) aluminum alloy cases. Others may have had better results than I have. I'm rebuilding my 1911cc engine now and just went through this a few months back. I tried the usual tricks -> vinegar, kerosene, oven cleaner, Aluma-Brite, etc. I also brought my case halves to a professional commercial metal cleaner that specializes in chemical cleaning. The cases halves came back "clean," but still very stained and oxidized-looking.
[At this point I had all of the machine work done including an align-bore, check for cracks, galley plugs removed/drilled/tapped, etc.]
Finally I just spent some Quality Time with my rotary tool and a bunch of small
brass cone brushes that I bought from McMcaster-Carr.
When I finished with that I used some elbow grease, denatured alcohol, and a ton of white coffee filters to make sure that every last pore was spotless. The alcohol does all the work, the white coffee filters are lint-free and show how clean the surface is. When the filter comes out clean, that part of the case is actually clean.
When finished it looked super but I knew it would oxidize again, so I then painted the exterior of the case with POR-15 engine enamel as a prevention measure. Others will say not to paint the case but I don't see why not. I didn't paint the case for bling value, but just so the next time I rebuild the engine I don't have to go through that insane cleaning process again. It's much easier to remove paint (even POR-15) than it is to remove all the aluminum oxidation and build-up.
I realize that none of this is at all necessary. If I were on the clock there is no way I would do this. But since I had the time and the inclination I just went with it. I'm super pleased with how my case came out. It was a great way to pass long winter evenings.
-marcus
QUOTE(JimmyG @ Jan 24 2016, 08:10 AM)
I do have a question or two along the way,
First on is shinning up the case and fan housing.I cleaned it with a pressure washer and degreaser and its clean and all but would like for it to be a bite brighter without painting. I would think there would be some kind of etching chemical still available that would show the beauty of the aluminum. Is there something out there like what I am thinking?
