I've got a number of pinhole leaks in a section of cast iron drain piping I need to repair. (I know eventually I'll need to replace the sections--Im looking for a temporary fix that will last a year or so until we've saved enough to have it done right.) The pinholes are covered with scales, but on the advice of a friend I scraped and wire-brushed them off. He said then to kneed the epoxy into a ball then work it into the hole. However, now that I have the scales off i see no hole (I guess because on the outside its a pinhole). Should I press the putty into the area where tge he was or attempt to drill it out with a small-diameter bit first?
This is a question simar to How can i repair a nail head size leak on a vertical cast iron sewer pipe in my basement but I'm asking a more specific question.