Can I flush out an aluminum radiator with vinegar or some other chemical?
When I anodized gun parts, we used lye first and it bubbled and fizzed and stank and corroded the aluminum immediately so they looked like hell, but it got rid of all the crap on the surface.
Then we used nitric acid bath and the corrosion immediately fell off and the part was instantly spotless. It was neat as hell to watch.
You could do something similar but if you had a spot that was slow to circulate, it could eat a hole there I'm sure.