Bill, I had a gnarly looking smog pump that was stained and had that white chalky corroded appearance. I used a solution that is made to clean a/c A coils. It is an alkali, I believe. Will have to look at it tomorrow and see what the ingredient is. It foams up and has to be rinsed thoroughly, but it did the pump justice IMO. I don't have any before pics. I get a chance, I will take a pic. Just an idea.