I've seen galvanic corrosion too many times on boats, and for a water block that's pretty bad. There is permenent transfer of the metal to the block. No amount of cleaning will ever restore that block to it's previous condition. It's possible to machine it away, but that would ruin the block. That's awful. I can only imagine the debris on that block before cleaning.

I said this in one other post. I'm purposely buying stuff that has no aluminum. Only copper and brass, and I better never find that in my loop. If something is advertised as brass or copper it better be just that. A company WILL be replacing all the damaged blocks and radiator if it's not. That's a guarantee.

It's one thing if it's advertised as aluminum. That's fine as a person can setup an all aluminum loop. It's an entirely different matter to advertise it as something it's not and cause damage. That's willful misrepresentation and negligence. We're talking about stuff here that can cost 4-500 dollars and on up into the 1000's if you go all out.