I have used the original Evapo-Rust product for rust removal on parts and pieces for my car and other projects. It works great. Can I say "amazing" or has that word been outlawed? If it was me knowing how the original product works I would give it a try. Reading the instructions on the Evapo-Rust Cooling System Cleaner I would buy enough to treat twice as instructed, 6 quarts.
Also do not use Distilled Water. Pure water is corrosive and will pull minerals from wherever it can get them. If you used distilled water that could be contributing to your issue. You want to use drinking water with "minerals added for taste".
Steve
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