Broken toilet cast iron drain pipe

[Hagrid]

The cast iron flange on my 4" toilet drain needed to be replaced. (I rather not say why). I removed all of the packing around the outside of the pipe, which in hind sight, I may not have needed to do. I purchased an Otey cast iron screw in flange. I lubed the threads, was I saw on some videos, and inserted it into the pipe. Started screwing and, after screwing in a few turns, got too hard to screw any more. I removed it and started over multiple times, with no success. Finally, i pounded it with a rubber mallet thinking the result would be the same as screwing it. Big mistake. A 2"wide part of the iron pipe broke off to a depth of about 4". A clean break. Just one piece, no fragments. What can I do, besides call a plumber? Here are some thoughts I had. A) Since I can put the piece back in, I can apply pressure from the outside, and it stays on perfectly. I thought if I filled the void around the pipe with cement, let it dry, then clean the inside of the pipe, apply a layer of epoxy, let it dry, then put in a different type of flange. B) insert some kind of liner 6"-8" long into the pipe and fill the void around the outside of the pipe with something. All I could find online was repair to a much deeper break or crack. Can you please advise me? I would say i have above average mechanical skills.

 

[Hagrid]

Additional photos

 

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[Sylvan]

Easiest way I found was to remove the old flange completely and install a new caulked flange using molten lead and oakum.

OR for safety call a licensed plumber who has experience.

Even though this video is wrong in the installation with dross on top of the ladle and not enough lead in the joint and the fact he used a cold chisel and not the correct irons his joint will still work.

 

[Sylvan]