Ok, the orange color is a dye you used? If not my guess it's a reaction compound between the aluminium rust that had caused the color, and for the sticky part coming from the blocks, it have to be the alumina. That can't be cleaned property since it's already rotting, the only solution is to change a new one or be professional refabricated. I never RMA a water-block before, but I think it's under warranty. Next time avoide aluminium made blocks, especially the non-painted ones.