I need to replace a cast iron clean out hub. If I drill out most of the lead sealant how do get it all and remove the male part from the female bell? I am sure it is rusted together after 100 years. There is nothing externally to grab onto. Or if I get most of the lead out will it just break free and pull the remaining lead and oakum out? This is a 4″ pipe going into the foundation and I do not want to beak any more cast or concrete.

Exactly why do you need to replace this clean out hub. If it is because the threads are rusted away you can buy an expanding rubber plug which has a brass bold and expander which you can insert in place of the old iron plug and avoid all the risk and labor of trying to replace the present hub. Other wise you will be better served with a oxyacetylene torch to melt out the lead and using heat to both burn out the oakum and loosen the hub. The hub probably has a retaining ring cast into the end which was used to help in expanding the oakum and lead when it was new and this along with the accumulated rust will present a real mechanical problem. If you absolutely do not want to break the bell, you probably will and then you will have a real chiseling and digging job on your hands. I would certainly examine the possibility of the rubber plug before trying to replace the original hub, and even if you do get it out of the bell, I’d still go with a rubber plug that fits the bell rather than a new cast iron clean out, that’s if you can even find one. Depending on your location a 4″ rubber plug should be available for under 50.00 or go on a web search for one.

What I need is to block the sewer gas form entering the basement. The threads on the cap have rusted away. The hole is 3 3/8″ diameter. A plastic 3 1/2″ hub will almost fit into the hole. Plan was to use vulcam caulking to seal it. I tried to buy a rubber plug a Lowes but none would fit. To small or to large. Is this a special order thing to get the right size?

A plumber suggested drilling out lead and replacing with a plastic hub. When the drain cleaner guys come they never access the drain there. Frankly I really like the plug idea. It is easy. If I break the pipe I am going to be in a world of hurt as the pipe is in the footing. To fix it would mean a back hoe and lots of digging, permits, and money. I’ll try to find a plug again. There has to be one out there as this is a common size pipe. Thanks.

Drilling most out is one way. Also, since it is put in by melting the lead and poured in, perhaps to remelt it would be logical. This would take a hot torch such as Mapp gas or an acetylene torch. Be sure it is not next to anything flammable. Plumbers are often setting buildings on fire with a torch.