PVC to cast iron - leaking joint


Old 11-14-08, 05:39 PM
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Join Date: Oct 2008
Posts: 6
PVC to cast iron - leaking joint

I'm remodeling the bathroom. I removed the old cast iron toilet waste pipe from the stack and attempted to replace it with PVC. I thought I did well, but no. The toilet isn't even connected yet and my joint is already leaking! This is waste running down from the stack from the second floor and running into the T where my new pipe connects.

So, here's how I connected the pipe to the cast iron tee. I removed all of the original lead and oakum, cleaned the inside of the bell with a wire brush, inserted the new PVC pipe, packed in oakum up to about 3/4 of an inch in, filled in the last 3/4 inch with plumbers epoxy. It looks great except for the bit of sewer water dripping from the underside of the joint.

Maybe I didn't pack the oakum in tight enough? Did I miss something? How do I fix this? Will I be able to remove the "hardens like steel" plumbers epoxy? Should I try using a Fernco donut instead of the method that I used?
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Old 11-14-08, 05:54 PM
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The epoxy should do the trick. I used JB Weld in the same situation awhile ago.
Old 11-15-08, 08:59 AM
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It almost seems impossible it should be leaking, based on your repair method.

It must have either got wet, in the hub, when you did your work, or, when it was setting up, the pipe sagged, under it's weight, before you got the flange anchored to the floor above.

You'd think though that you would have epoxied it after the entire section was anchored and rigid. Did you? If yes - then we are back to the water in the pipe wrecking it, theory. Either that or that bonding agent does not stick well to PVC.

I would think this would be repairable, superficially, as long as you repair while dry, and the bonding agent can stick well to PVC. You might want to sand the PVC first.
Old 11-15-08, 09:48 AM
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Join Date: Oct 2008
Posts: 6
Fixed - I hope

I pulled everything out. It wasn't that difficult after heating the outside of the CI pipe for a minute. I'm glad I did because I saw a big boo-boo. When I first put the pipes together, I though that putting a little oakum at the front of the pipe might make a nice gasket in case the PVC didn't reach all the way back. I created a nice clog in the pipe before we had a chance to use the toilet! So, I'm sure that contributed to why the water was trying to get out around the pipe.

So, I bought a donut from the plumbing supply store and used that. I soaped it up real good and put the donut into the cast iron first. I tried putting it on the PVC first, but that didn't work because since it was soaped up, it was just sliding up the pipe when I tried to push it into the CI. I had to use a 3LB hammer to get the PVC pipe into the donut. I'm not going to glue all the other pieces together until I'm sure that this isn't going to leak again, but I feel pretty confident that it's good now.

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