I've been using the advice on this site to replace a cracked length of cast iron and a cast iron Y junction with PVC, and up until this point, it's been going great.

It's all back together now, but where the PVC goes into the cast iron bell, is leaking. I don't want to replace this because it is a junction piece that goes in 4 directions and it's in my wall, so it would take some major demolition to get it out. (already had to tear up half my floor to get this part done.)

I used a donut coupling, I didn't need to shave any off to get it to fit, but it was a very tight fit. It is fully seated into the bell, and it is now leaking out the bottom, between the bell and the donut. Any suggestions? Is there some type of adhesive, or could I put some silicone around the donut to get a better seal?

Is this what you used and did you follow these instructions? http://www.fernco.com/files/installation-instructions/donut_install.pdf

Yes, that's how I did it. The inside of the bell did not look like it was in that rough of shape, the donut is fully seated. Would it make much of a difference if the pipe isn't the full 1 1/2 inches deeper then the end of the donut, since the leak is coming from between the pipe and the donut? I think it is at least that deep, but I can try and pull it out and check that, but I'm out of town until Friday.

I suppose though, that if the PVC isn't all the way through the donut, it's not going to be fully expanded, so it will not seal as well will it.

If I make sure that is in far enough and it still leaks, then what about something to act as a sealent? Is that even realistic, or should I not even try it. I just don't want to have to tear the whole wall out for this one pipe!!

Oh, actually, now that I look at that picture a little closer, I didn't beat the outer flange of the donut all the way down into the bell. I have the flange pressed up to the outer edge of the bell. Well that's going to stink, I'm going to have to cut out more flooring to be able to get access all the way around the bell to be able to beat it in that far! But I guess I can see how that will definitely make a much tighter seal! Hope that works and thanks a TON for the illustration!

Sorry, this is the first time I've used this forum, so I added my comments on your question as new answers, thanks for your help though!

Would it make much of a difference if the pipe isn't the full 1 1/2 inches deeper then the end of the donut, I didn't beat the outer flange of the donut all the way down into the bell.
Pull the connection and doi it right.
The donut should be forced all the way in and the PVC should go all the way in the bell until you feel it hit the base of the bell.
Follow the excellent link that Bob put up for you. Good luck, Tom

Well, I got home early and worked on this for a few hours, and just managed to chew the outer ring of the donut up. It's a 2 inch PVC pipe going into a 2 inch CI bell, so I don't have the think face of rubber to beat on as is shown in the top illustration of the link.

The outer flange of the donut sticks out almost to the outer edge of the cast iron bell, I would beat in a section, and it would pop right back out as soon as I removed the wedge, and I broke 4 wedges too. I took a picture of it, but can't find a way to embed it into this message.

Pushing the PVC all the way into the bell 1st did stop the leak for now. I drained a half tub of water and flushed the toilet at the same time and no leaks, so we can at least use it for the moment.

Should I decrease the size of the PVC to 1.5 inches and get the donut with more surface area? Would that make it easier to beat in? Also I read about two different types of cast iron, service weight and extra heavy, and that will make you need a different size of donut. I couldn't find the letters on the cast iron pipe I the wall, so I checked the pipe I had already removed, the only letters were CFCO and an N. Does this mean it's probably the extra heavy size? Thanks again!

Have you been greasing the donut with plumbers grease?

Position the PVC straight into the bell. It won't go in cocked and Use plenty of grease and take a file and bevel the edge of the PVC pipe. Seat the pipe until you feel it "thunk" against the bottom of the bell. Good luck, Tom

No, I hadn't, the illustration said to use a soap solution, so I used that. I will get the plumber's grease on the way home tonight and give that a try.

The grease works much better than soap. The grease is slick and also acts like a caulk to a small extent

Regarding "CFCO"

I have the same situation. My 4" bell that I having trouble with is also marked CFCO. It does look different than other bells marked STD in my drain system. The OD of the CFCO bell has an indented area/band that is about 1/4" deep and 1-1/4" wide, starting 1" back from the face of the bell lip.

Is the ID the same as STD bells? Should the donut fit with this bell?

I am going to keep working to get the PVC and donut in the bell. I will reply with results.

According to http://cad.jhu.edu/doc/lib/pipelib.pdf, a PIPE FITTING LIBRARY™ Catalog, generic CFCO if just a female connector. Still working on assembly.

Hi Sbudrow...

In my area cast iron pipe/hubs are marked SV for service weight and XH for extra heavy and the hub sizes are different.

Let us know how you make out, OK?

Mark

According to a Pipe Fitting Library Catalog at http://cad.jhu.edu/doc/lib/pipelib.pdf, generic CFCO is a female connector.

You might try a local plumbing supply store and see what they recommend for your hub as they do make different sized donuts... they'll know for sure.

At the larger box stores you just never know what someone has thrown in a box labelled one way only to bring the part home and find out it is the wrong one...

Initially I had tried unsuccessfully to install the donut after the PVC was inserted into the bell. After a bit of research, I found of number of persons recommending installing the donut, then inserting the PVC. I was attempting this assembly with the recommended plumbers grease, but still running into problems -- either the PVC wouldn't go in, or the donut hung up on the PVC and got folded under the lip of the bell. So I pull the donut insert out one rib, tapered the PVC OD, and pounded the PVC in using a block of wood and a hammer. The donut did not get pulled in all the way to its outside flange, but he fit was solid and I could not get the PVC out anyway. I have left the assembly this way with no signs of weapable.

As you know, this isn't right sbudrow...

Donuts used in tight spaces are almost always tough work. In my area we use home made lead hammers to pound the pipes into the donuts, or we use an oakum and soil seal/lead substitute... see below.

If the donut fails/leaks then consider the soil seal and oakum... easy install that is very reliable.

Happy New Year!

Mark