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bofusmosby 01-31-2008 12:05 AM

How to repair a hole in cast Iron pipe?
I am getting ready to replace the toilet (seal leaking) in my house, so I went under the house to check out the plumbing, so I know what I am up against. Everything I have done on this house has turned into a big job. You know, the "can of worms". Well, the toilet I am replacing is one of the newer types, so I saw from under the house, there was PVC going from the under-side of the toilet, going into the old cast-iron pipe about 4-5 inchecs below the floor.

About 3-4 inches above the ground, I noticed a small hole in the cast iron pipe. It looks to be about a perfect 1/4 " hole, that looks to have been drilled. The water isn't flowing out the hole, because it looks like there is some paper clogging the hole, so the water is just slowly seeping, with a small wet spot surrounding the pipe going into the ground.

First, would there have been any reason for this hole to have been put there, and second, what is the best way to seal or plug this hole. Any advice would be greatly appreciated.

Thank you!

Mike Swearingen 01-31-2008 02:02 AM

The "best way" is to cut off the cast iron with the hole and replace it with PVC white plastic connected with a no-hub coupling from the cut-off to a new toilet flange bolted to the floor (with ony the thickness of the flange itself above the finished floor level). You can cut cast iron with a reciprocating saw and metal cutting blades or with a snap cutter made for the purpose.
Another way is to sand the area around the hole, run a bead of clear silicone caulk around it, wrap it with a piece of rubber (gasket material or inner tube) and clamp over it with a stainless steel gear clamp(s).
Good Luck!

bofusmosby 01-31-2008 06:44 AM

Thank you Mike for your response. The hole is about the size of a pencil eraser. I feel that someone from a foundation company that had done work on my house several years ago put this hole there. The pipe appears to be in great shape, except this perfectly round hole put in the pipe. This foundation company tried to back out of the work they had said they would do, and I let them know that I would not be paying them the second half amount of money until they did all the work they said they were going to do. The owner of the foundation company called one of his workers off to the side, and whispered something to this worker, just before they started to do the final work I told them they must do. Just a gut feeling though....No proof.

Since this pipe is under the house, and there is little clearance under the house, I am going to try to repair the hole. Looking into the hole, I can see the complete thickness of the metal, and believe that there is no other way that hole could have gotten there.

Thanks for your advice!

jogr 01-31-2008 10:29 AM

You might try a good expoxy if you can get the hole clean and dry. Otherwise go for Mike's clamp and rubber gasket.

bofusmosby 01-31-2008 05:47 PM

Unfortunately, because this hole is in the middle of a "t" connection, there is no way of installing a clamp, and rubber patch. I got some of this Epoxy putty. I plan on using a wire bruch on the pipe to clean it, then wipe it down with rags with acitone. This evaporates fast, and will remove all the rust dust. I hope I am able to clean inside of the hole as much as possible, and use this putty.

dyier 01-31-2008 06:52 PM

If the hole is small as you say get your hands on a chunk of hard roofing tar (not Henery's roof mastic, the hard stuff they melt down for flat roofs). You heat the end of it to get it soft then smear it over the hole untill it is sealed. When it cools it will bond and be as hard as a rock.

nacko 01-31-2008 08:45 PM

find a machine screw that is just bigger than the hole and is about 3/8" long. go to this chart and get the drill size and also buy the right tap

drill out the hole, tap it, get some epoxy putty, or some super blue thread sealant, put the thread compound in the hole, screw it in, voila, good for life.:thumbup:

Marlin 01-31-2008 10:47 PM

I've never tried to drill cast iron but I'm positive it would be very difficult. The same goes for attempting to tap it. You are also now running the risk of cracking it. Putting a screw in the pipe even if it's just in a little bit will create a magnet for clogs as things get stuck on it and build up.
The only correct way to fix it is to cut it out and replace the piece.

Mike Swearingen 02-01-2008 02:25 AM

I agree with Marlin.
Cut this out and replace it with PVC fittings, etc. Then, you never have to worry about it again.
Sounds like the foundation company jerks deliberately sabotaged your line with a drill.
Unfortunately, such a small thing is not worth the legal hassle and expense to take any action, and proving it would be another story also.

jpplumber 02-01-2008 02:45 AM

Ideally it would be best to cut it all out. The next best would be to use either the epoxy or the tar. By all means do not try to tap it and insert a screw into the pipe.

bofusmosby 02-01-2008 07:42 AM

Thanks guys for the advice. Where the pipe is located, makes it out of the question for replacement. Its just a small hole, perfectly round. I see no other way this hole could have gotten there. Now I am wondering what else those idiots might have done. I would never try to put in a screw. The risk is too great. If it were located elsewhere, I would just replace it. I am going to try some of the epoxy putty. I'll be doing this this weekend. I will post my results.

Thanks again for the advice guys. I appreciate it!

bridjon 12-05-2008 01:55 AM

How did you fix it
I have a similar problem in a verticle cast iron pipe. What did you plug the hole with?

bofusmosby 12-05-2008 05:08 AM

Gezzz, I can't believe that I forgot to post the results.

I used the epoxy putty, and it worked fine. I used to sandpaper (rolled into a small tube) and cleaned the inside of the hole, as well as sanding the outside of the pipe to remove any loos dirt, rust, etc.. Then I applied the epoxy putty, making sure that the epoxy also went into the hole a little.


majakdragon 12-05-2008 11:43 AM

JB Weld will solve the problem. Just don't overfill the hole to make a "hanger" for paper when flushed. I have patched cracks in water pumps with it when the company could not remove the pump or would not buy a new one at the time. No patch is ever as good as replacing the pipe, but sometimes it is not an option at the time.

4just1don 12-05-2008 01:02 PM

Somebody took ALOT of time and wrecked numeerous drill bits drilling cast(without cracking it) Dont overlook a previous homeowner etc, that wanted a dehumidifier drain,,,or other similiar small drain tube installed

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