the plumbing in our house is from 1936. We noticed a large stain in the ceiling, tore it out to reveal the cast iron soil stack (runs from the upstairs bathroom turns a corner then runs straight to the basement) and found the leak was around (very bad leak) the lead joint. My husband finally got the lead joint free using a cold chisel, and we took turns scraping and cleaning out the oakum. We purchased a 4x3 inch donut. Our cast iron pipe is CI not SV. We fit the plastic hub into the donut, coated the donut with softsoap to make it easier to get in. However, after hours of trying, it still would not go into the cast iron pipe.
We could get the rubber donut in without the plastic hub, but once we again placed the hub into the donut, it became almost impossible to get in. It's in a difficult position as the part we cut faces a kitchen window with the sink undeneath it. We pounded for hours ,still would not go in. We purchased the rubber donut and hub at the local home depot store. Any suggestions on how to get the donut and hub to fit the cast iron pipe? It was the correct size. We plan on the repair section going from the cast iron to PVC.

Hold on! You're going to hafta splain some things to me. You say."our cast iron pipe is CI not SV." Do you mean PVC because SV is a abbreviation for service weight cast iron.

"We purchased a 4x3 inch donut. our cast iron pipe is CI not SV. We fit the plastic hub into the donut, coated the donut with softsoap to make it easier to get in. However, after hours of trying, it still would not go into the cast iron pipe.
We could get the rubber donut in without the plastic hub, but once we again placed the hub into the donut, it became almost impossible to get in."

Why a 4 X 3" Duel-Tite Gasket,(donut, see image) are you reducing the stack down from 4 to 3 inches? The reason you are having so much trouble is that the gasket is made to go into a cast iron hub and not the other way around. Even then we sometimes have to bevel the rough edges on the PVC pipe and trim off a few rounds of rubber off the gasket to get it started.
Now! Whoever told you how to convert cast iron to PVC. It's hard enough when you do it the right way, impossable to do it the way you were going.
Since this is a older house I'm gonna assume the cast iron stack's 4".
Forget the gasket. Purchase a couple of 4" No-Hub Bands, (see image) and join the bald end of a cast iron pipe to another bald end of PVC. Since you failed to inform us about where the PVC will be run to and the fittings involve about all I cab do is instruct you on converting to PVC.
Sorry you had all that trouble. The next time you see the dude who advised you give him 20 lashes with a wet noodle and inform him he would never make it on one of my crews. Good luck, Tom

Our cast iron waste pipe was made before WW2.
We were told that there were 2 types of cast iron; pre-war (which is ours) which is heavier cast iron (thicker), and post war which was thinner. The problem we are having is we need a 44UX305 donut. The 44U305 donut is what we are having problems with. It won't go into the hub no matter how hard we try to pound it. We looked on the internet, found it at fernco. However, fernco says we cannot order just one through them... Home depot and Lowe's don't carry it.
Why won't the 44U305 donut go into the hub?

Just to say.. the PVC will run up to the new upstairs toilet. It's a pretty straight shot up with a bend in it at, I think not much pipe length.
The plumbing is weird in the house. The soil stack comes up from the basement runs in the wall between the kitchen and hall (downstairs bathroom close to hall and kitchen) then for some ungodly reason tees off to go up. Kind of turns a right angle in the ceiling then proceeds to the upstairs toilet.
We figured it might be because the toilet downstairs is located on the opposite wall of the toilet upstairs. We also noticed the cast iron in the ceiling resting on one of the joists. We Don't want to have to cut the joist to do anything. We bought some heavy duty metal plates just in case we have to cut the joist. We had a plumber come and take a look at the plumbing. He just shook his head, and said he'd call in sick the day they'd have him come and work on the house. The house is 4000 square feet.

Your today sounds pretty much like my Saturday, except mine was only a 2" tie-in.

I generally find or build bracing substantial enough to allow me to lever the pipe into the donut with a 2"x4" -- Even if that means starting with a longer or shorter piece of plastic pipe than I need -- Longer can always be cut off, and too short can always be added on to with a coupling, in other words, the length of the plastic pipe is dictated by the placement of the bracing being used to lever in the pipe.

Dang... I'm really going to have to start taking more pictures.

BTW, you are doing it in the reverse.

The donut goes into the hub first, and then the pipe goes into the donut.

I also use clear silicone instead of soapy water -- Silicone is a lot more slippery than soapy water.

Also, the pipe should be fully seated into the bottom or back of the hub when finished.

thanks for the info... we have a small round pvc piece that fits into the donut then the pvc pipe should fit into that... We can sort of get the donut in by itself, but boy put the pvc piece into the donut before putting it into the hub is impossible. We'll try the 2x4 approach on Saturday when our frustration over it calms down! We even tried using a car jack to get the leverage to push the thing into the hub but it just would not go in!
Your advice sounds good... we'll try it on Saturday!

Another thing to consider, if you have enough space between fittings:

It is much easier to work with a 4"x4" donut than it is to work with a 4"x3" donut, because you are displacing less rubber.

If you have enough room, use a 4"x4" donut, and then a long enough piece of 4" PVC to fully seat into the hub and still leave enough pipe exposed to glue on a 4" PVC to fully seat into the hub and still leave enough pipe exposed to glue on a 4" 'reducing coupling'.

Transitions from cast-iron to plastic are always difficult, and I am a firm believer in dumbing down the procedure for my students at the local Voc-Tech where I teach Seattle's next generation of plumbers how to get the job done with out beating their bodies into a bloody pulp.

One more tme. YOU'RE DOING IT THE HARD WAY!! And not only that but you're doing it backwards. Didn't you read my post? And what size is the stack anyway? We have never used Duel-Tite gaskets on a cast iron vertical stack. We used them under the slab but above we used No-Hun Bands. Attempting to use donuts on anythng but a horzontaln installation is, in my opinion, a lesson in futilely. ThE reaon being that you have to lever the pipe into the donut, WHICH IS IN THE HUB and it's difficult to get a purchase for leverage when it's verical. Now you can be stubborn and insist on using a donut but if you want to do it the easy way you'll follow my instructions put forth in a earlier post. And BTW, Duel-Tite has a lubricant it recommends for their gaskets. I also see you have checked Fernco Neoprene Couplings. Bad idea for anything but a temperary repair and certainly not on a vertical stack.
Regards, Tom

I would have made the same suggestion regarding no-hub bands, Tom, but it seems they have already removed the 4" cast iron from the hub.

Thanks Growler,

I was under the impression that we had two bald ends to connect. OK, new plan. Rather then attempt to force PVC into Duel-Tite Gasket in the vertical position I would caulk in a short piece of PVC into the hub using oakum and lead wool. Then you can glue on a PVC coupling and go from there. While I have poured and caulked lead joints for PVC into a cast ron hub for a home owner lead wool is much easier and doesn't require a lead pot and furnace. The joint will still have to be caulked but it's a lot easier then fighting a donut n a vertical stack. Good luck, Tom

The donut goes at the y junction is. It is the part that branches off from the main cast iron soil stack and goes to the upstairs toilet. The cast iron pipe is 4 inches. The PVC to the upstairs toilet would not be that long of a piece. That is the joint that was leaking. (at the y. The lead joint leaked right at the "y".
I know this sounds frustrating and the advice is really good.

And the donut we figured goes into the hub...
A plumber is out of the question... too expensive anyway... we just put a new roof on the house which took most of our available resources, The plumbing is original 1936... That is when the addition was added onto the original house which was built in 1830.
Down in the basement, we did see that the previous owner had cut a section of the stack and attached PVC to it. It seems to be holding well.

What I don't understand is, if the leak was at a lead joint, why didn't you simply recaulk the lead joint. This would have stopped the leak and you would have been home free.
Regards, Tom

My husband looked it at the leak for a long time. He is an engineer. He thought that the way the lead joint had cracked in several places; that with as large as the cracks were that it would be best just to re-do the whole thing. We did not do this lightly believe me. We talked about it for quite awhile and came to the conclusion that this was the best way to go with it. It was a really bad leak.

I hate to tell you this but it isn't the lead that seals a lead joint. The okum's packed in and swells sealing the joint. The lead simply keeps it packed and secures it in place. Unless the cracks were in the cast iron hub the joint could have been recaulked then if it still leaked then you coud have torn it apart. As it is you are left with no choice but to convert to PVC at the hub.
If this were my call I would cauk in an piece of PVC using lead wool and oakum and couple to that. Note: I suggested lead wool because there aren't too many of us left that remember how to pour a lead and oakum joint that converts Cast iron to Plastic. I would suggest calling in a plumber with lead working experience because special tools and knowledge are needed.
This might just be your easiest out. However, it's not all that difficult to yarn in oakum and then caulk the joint. If you wish I can tell you what tools to rent and walk you through it. Interested? Regards, Tom

Very thorough and good detail