Removing blackist mottled discolored on engine cases.

[gearman]

77 convert,I don't want to glass bead the cases but have any of you found a chemical that would remove or lessen the the  staining. I have used Trailer brightener in the past but it strips the zinc off of the fasteners.I think it was phosforic acid.SP.Thanks all.

[canuck750]

I think any acid will remove the zinc plating on fasteners. You could try soda boasting, pretty effective but slow work.

[nc43bsa]

Or you could clean the cases as well as you can and spray them with cast aluminum paint.

I did that on my rear drive and rear wheel hub.

[blackcat]

I found a guy who has a large mobile soda blasting setup who usually does whole cars for restoration, and he has shot the engine, transmission and final drive for something like $75 bucks. Well worth the money and all were blasted completely clean.

[Sheepdog]

I use WD40 and 0000 steel wool on dirty aluminum cases. Four-aught wool is fine enough that no scratches will show. The WD40 is a solvent that is mild, but complements the steel wool well. In addition, the WD40 leaves a film that protects the aluminum and makes future cleanups easier.

If that doesn't work, soda-blasting will do the job. Baking soda is a great media for aluminum as it is mild-yet-effective and the residue will dissolve with a little water.

[Antietam Classic Cycle]

Use the aluminum brightener/trailer cleaner and replace the fasteners? If they're the originals, they're about as hard as lead anyway...