I used this epoxy as a temporary fix while waiting for a radiator shipped from rockauto. Lightly sand the area and clean with alcohol, allow to dry and apply epoxy.
Worked fine during the couple of weeks before I got to replacing. No seepage under the epoxy then. I am sure it would have gone longer, but I would not consider this a permanent fix.
https://www.permatex.com/products/sp...or-repair-kit/