Home>Discussions>PLUMBING>3 Inch Cast Iron Drain Pipe to 3 Inch PVC at Coupler slight leak?
31 posts / 0 new
Last post
Mastercarpentry
Re: 3 Inch Cast Iron Drain Pipe to 3 Inch PVC at Coupler slight leak?

Any sandpaper will do here. The reason plumbers use emery cloth is that it lasts a lot longer and isn't prone to tearing when used like they do- and the 2" strips are easier to use around plumbing.

While my recommendation for sealant isn't "on the books" anywhere, it is how I've solved a few persistent leaks and it seems to work so long as you have enough solid and uncoated area for the coupler to 'bite' to for physical attachment. Silicone is slippery so you can't slather it on and not wipe it or the coupling might slide off.

Though I haven't tried it yet, I think a more ideal sealant here would be Yamabond4, a proprietary non-hardening sealer made for motorcycles. "Threebond" also makes a similar product now. That stuff has some amazing sealing powers at (non-recommended) thickness that leave other sealers failing. It's non-hardening, sticky as heck, and resistant to about anything except strong acids. Outside of motorcycle mechanic work it's practically unknown but those in that industry swear by it.

Phil

MMeehan
Re: 3 Inch Cast Iron Drain Pipe to 3 Inch PVC at Coupler slight leak?

Thanks for the information but now that I have looked at it the PVC does not more up down left or right so getting the new Coupler in place will be a bit tricky to slide in place with not way yo move either of the pipes not that they are fixed in place I see why they fit everything in place the added the PVC that goes up first because there is not way to tip the PVC off a little and lift it up and slide in into the new coupler...Being both the PVC Pipe and the Cast Iron Pipes are solidly in place and no movement at all in any direction looks like I am in for a little more than just changing the Coupler looks like I will have to some how cut the PVC or something because there is no room to get the Coupler in there with tearing the rubber part to connect to one pipe and then the other. never like plumbing guess I am just going to have to cut it where it comes over to the pipe running down and re cement / glue it in hopefully in the coupler overhead and place with a new pvc Couple once I have the fernco coupler in place and tip it into to align it with the other section of PVC.

Just move trips to the HD for parts and pvc cement...

MMeehan

dj1
Re: 3 Inch Cast Iron Drain Pipe to 3 Inch PVC at Coupler slight leak?

There you go, I'm sure you can force it in.

It's like forcing a coupling between a couple of sprinkler pipes.

Mastercarpentry
Re: 3 Inch Cast Iron Drain Pipe to 3 Inch PVC at Coupler slight leak?

With effort, you can get a Fernco coupler on with maybe a 3/4" gap. It's going to need shoving, a dull flathead screwdriver or two, and maybe some liquid soap on the PVC or that end of the coupling. Take the clamps off first, slide them on the pipes past where you're working taping them out of the way as needed. Or unscrew them fully and wrap them back on when the coupler is in place. If you use a sheathed "hubless" connector you'll need a lot more space and the clamps are probably riveted in place making it even more fun.

When working on plumbing in an existing structure, please be sure to keep all children away from the work area. No, not just for their safety- it's because you don't want them to hear the words you may find yourself saying :mad: And now you know why I don't like doing that kind of plumbing work :p

Phil

MMeehan
Re: 3 Inch Cast Iron Drain Pipe to 3 Inch PVC at Coupler slight leak?

There might be easy but both the PVC and the Cast Iron Pipes are SOLID in place there is no way to move them in any direction. And the way they put it place when it was changed to PVC from Cast Iron they put the 90 as the last piece having the Coupler in place on the cast iron and put the pvc in and then adding in the 90 as the last piece they glued in. I will have to cut the pvc just away from the 90 where it heads for the toilet and tub drain. I loosen the coupler and could not move the pvc pipe an 1/4 of an inch up and as stated if it is 1/2 between them now I would be lucky but neither will bung in any direct. So I will have to cut the PVC with my sawzall and push it up to replace it I am going to also check the edges on the cast iron and see if there is any burrs that might have rub the rubber part and is causing the leaks it is on 2 sides about 2 inches apart of the 3 inch cast iron pipe.

I appreciate the suggestions but I just need a 3 inch PVC Couple and some cleaner & PVC Cement Glue and it will be good just waiting for the weather to warm up some maybe 40 degrees on a weekend so if I have any issues I can make my three trips to HD for the stuff since I am good with Electrical but plumbing I have never had much luck with even when I added an Aprilaire Furnace Humidifier the pvc tubing would always leak when I would turn it back on after being off over the summer months it is now copper line and no issue but that was a multi trip to HD trying several different plastic connectors and then just got the copper line and fittings and redid it... No more leaks and that has been 7 years now...

Again thanks for all the advice...

MMeehan

Mastercarpentry
Re: 3 Inch Cast Iron Drain Pipe to 3 Inch PVC at Coupler slight leak?

Something that might help you on the PVC is a "Slip coupler"- regular couplers have a ridge in the middle which stops the coupler from going more than half-way onto a pipe. "Slip couplers" are totally smooth inside and can be slid flush with the end of the pipe. You may have to go to a plumbing supply for that part, I don't know if the big box stores carry them. Anytime you use a slip coupler be very liberal with the glue so there's enough on it when you slide it into it's final position and be sure it's mid-way to both pipe ends

Phil

MSSP
Re: 3 Inch Cast Iron Drain Pipe to 3 Inch PVC at Coupler slight leak?

the correct coupling need is what is called a CP33 Since cast iron is smaller outside diameter than sched 40 PVC. The reason it may have started leaking is the fernco was old when it was put on or it simply was not torqued the correct amount

MMeehan
Re: 3 Inch Cast Iron Drain Pipe to 3 Inch PVC at Coupler slight leak?

The CP-33 by Mission Rubber is not a readily available coupler as the Fernco one is. I could only find the Mission Rubber CP-33 at Amazon and the Mission Price on their website is close 16.00 but Amazon is 21.00 plus the S&H. Checked a couple of other sellers Websites though they have a link suggesting they carry it they don't but carry Fernco or they are out of stock? The Fernco is 8.00 and available at many places including HD.

Thanks for suggestion I will keep looking but it is not as readily available.

MMeehan

Mastercarpentry
Re: 3 Inch Cast Iron Drain Pipe to 3 Inch PVC at Coupler slight leak?

While there may be a better-sized connector for this, fernco's have always worked well for me in similar situations. Just sayin!

Phil

MMeehan
Re: 3 Inch Cast Iron Drain Pipe to 3 Inch PVC at Coupler slight leak?

Well here is an update and it is not good either but here it is...

My kitchen sink drain was running slow so I poured some Liquid Draino in hopes of clearing the drain... Well now the section of Cast Iron Main Drain Pipe has a Crack about 18 inches long down the side from the Fernco Coupler so now it looks like I will need a Plumber to come in and break up my basement floor and replace the cast iron to the fitting that is attached to the cement floor. Not sure if the cast iron is done, if any of the pipe underneath the floor is salvageable or if they will have to break up my basement floor and replace it to where it connects to the pipe that was replace 8 years ago from just outside my basement wall to the sidewalk. even though the problem then was on the city's side of the sidewalk I had a new drain line installed and they then could get a snake out the line where tree roots were. The Small Clean out inside was too small and 3 plumbers could not get farther out to snake it out. So now I have a clean out in my front yard which today is very common being the lines inside are only 3 inches and the outside is 6 inches...

So I guess this is what happens with an "OLD" Home a money pit... As I see it.

Won't need a replies even though I have a new Fernco Coupler it will soon be PVC I will now have to tape up the crack and save up for what a Plumber will cost to get this Repaired / Replaced!!! But it is never low cost... So much for owning a home as good financial decision lost 1/3 of its value and now everything is failing...

Like I mention in the Bathroom Section this is my last Post here at TOH will just pay what I can and have someone come in and do the repairs it is more time and money but I guess it will just be another bandage like the last major plumbing repair.

MMeehan

Pages

Sponsored Stories

TV Listings

Find TV listings for This Old House and Ask This Old House in your area.