problems with sewer line

[JTeller]

Hi All,

Had a problem with the sewer system on the second floor.

Ended up opening up the wall on the first floor and had to cut out a three-foot section of 4" cast iron sewer line. Sealed up the system by installing a 3-foot section of 4" PVC (sch-40) using two 4" Fernco rubbers.

I can't get the Ferncos to seal. The top Fernco weeps just enough to show a moisture ring at the top. The bottom fernco has significant leakage at the bottom. I tightened the clamps in stages with a screwdriver and then switched to a ratchet with 1/4" bit. The Fernco rubbers are simply not sealing on the cast iron.

Ugh. I'm at a loss. How can I seal this beast and still be able to get access in the future???

[hrhofmann]

How rough is the surface of the cast iron pipe? Also, maybe you are just being too weak in your tightening.

[Dean Hoffman]

Could you put some type of caulking or silicone sealant under the Ferncos? Would a couple wraps of the stretchable electrical tape under the Ferncos do any good?

[Sjouke Burry]

JTeller wrote in news:k2vvj5$npg$1 @speranza.aioe.org:

Fill the whole connection with silicon paste, then tighten the clamp.

[recyclebinned]

My guess is that your corrosion crack is extending past the point that you cut.

[DanG]

I suspect that you used a flexible coupling like one of these:

make no attempt to keep the piping lined up. I also suspect that your new pipe is not a good fit in the old pipe run.

Change out the couplings to one of the shielded type:

"No Hub" clamps work well on cast iron/PVC connections. These hold the pipe intersection in line. The new pipe should have an

1/8 to 1/4 gap at each coupling.

[TomR]

One person wrote,

"My guess is that your corrosion crack is extending past the point that you cut."

I think that may be a possibility, especially since you wrote, "The top Fernco weeps just enough to show a moisture ring at the top". Seeing that on the top connection seems unusual to me.

But, if it is not a cast iron pipe that is still cracked, the other thing that I would try is to sand/grind the outside of the cast iron to make a smoother surface for the Fernco to seal with, and also add 100% silicone caulk in the connection between the Fernco and the cast iron to help it seal better.