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 Cast iron stack leak
Author: NBMT91 (NJ)



Hello everyone,

This image is from the second floor of a friend's home. He has asked for my help in finding a solution. He does not currently have funds to hire a plummer to preform the major repair I believe this will need. At this point we are looking for temporary solutions. Something to remedy the problem for the time being. The pipe does not have any readily visible cracks, front or back. There is no 'drip' just a slow ooze around the joint. I have experience in construction, but mostly carpentry not plumbing. Please word your answers accordingly. ;)

Thank you for your time

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 Re: Cast iron stack leak
Author: hj (AZ)

Rule #1 in plumbing: Water flows DOWNHILL, so there is no way water can come up OUT of that joint.
Rule #2. If water does come out of a leaded joint, you take a hammer and a dull chisel and pound it down.

Post Reply

 Re: Cast iron stack leak
Author: steve (CA)

There's water stains on the backside of the sheetrock, upper rightside of the photo. Do you know where this came from? What initiated the opening of the wall?

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 Re: Cast iron stack leak
Author: packy (MA)

good temporary fix 101...

carefully heat the joint with a torch. a small inexpensive propane model will do. try to get it nice and hot all around. don't hurry it take a few minutes.
get a plain old bowl wax from the hardware store. when the joint is nice and hot, rub the wax all around. it will melt and find its way into any cracks. leave it cool and you should be good for a long while.
note, aim the flame directly at the lead..

Post Reply

 Re: Cast iron stack leak
Author: kingshakabobo (IL)

Is there another fitting or "t" above the view of the photo. It appears the cast starts to curve just past camera view - shadow shows a curve. Is it a t?

Post Reply

 Re: Cast iron stack leak
Author: NBMT91 (NJ)

Steve, I'm not sure about the water stains. They are old and dry. The wall was opened, not because of any apparent problems, but because they were interested in adding a washing machine hook up near by... but that's another story.

Post Reply

 Re: Cast iron stack leak
Author: NBMT91 (NJ)

Packy, that sounds like an awesome tip. Thank you!

Post Reply

 Re: Cast iron stack leak
Author: NBMT91 (NJ)



Ok, sorry guys. Photo bucket was not cooperating. Finally got a better picture up. Hopefully this makes a little more sense. Any additional suggestions? Clearly there's been problem(s) here for quite some time.

Post Reply

 Re: Cast iron stack leak
Author: kingshakabobo (IL)

You say this is second floor. Are there any fixtures above? Or is this all vent above the t?

Post Reply

 Re: Cast iron stack leak
Author: NBMT91 (NJ)

kingshakabobo, correct. Besides the T (bathroom sink) it is all vent.

Post Reply

 Re: Cast iron stack leak
Author: kingshakabobo (IL)

Have you run the sink to check for leaks at the "t"? Maybe plug the sink and fill it to the brim then let it drain. Feel/look for leaks at the t. That galvanized drain from the sink looks a little corroded at the bottom.

Let's see what the pros think now they can see there is a "t" above the hub.


I'm not a pro/plumber.

Assuming you find that galvanized drain is leaking at the "t" I would cut the cast iron "t" out. Cut above the upper dry hub partially showing if you have enough room (or 5 or 6 inches below upper hub if no room). Cut below the leaky "t". Cut the galvanized sink drain leaving 3 or 4 inches showing.

Wherever you cut the vertical cast pipe, try and cut off the raised lettering so your coupling seats flat.

Install a new pvc "t" with a short length of (2 inch?)primed and glued pvc pipe to join the galvanized drain. And two short lengths of (3? Or 4 inch?) primed and glued pvc pipe to make your connection above and below.

Make all three connections with banded rubber couplings. I prefer the unbanded rubber couplings because they are usually longer and therefore easier to work with. But banded couplings keep the pipes from shifting. You will be securing the pipes anyway so that shouldn't be a problem. But banded couplings are the "right way"

A 4 inch grinder with a diamond wheel will cut the cast iron like butter. I think you will have to sawzall the galvanized pipe.

The tricky part will be not nicking the water lines. Maybe slip a piece of plywood between the pipes to protect the copper.

Also, you have to secure the cast iron pipe above and below your cuts. Either with blocking behind the cast pipes and strapping them in place. Or riser clamps - I think Home Depot carries the clamps. Or a plumbing supply house.


Make sure you know where house water shut off is before working around those supply lines:

[m.youtube.com]

Post Reply

 Re: Cast iron stack leak
Author: NBMT91 (NJ)

kingshakabobo,

I thought at first that it must be the sink T that's leaking, but it's not. I realize it's difficult to see where the water is coming from in the pictures. Here is a better visual. First I did as you said, and filled the sink to the brim, then let it drain. Afterwards I used a price of paper towel to give an idea of where the water is coming from.







Edited 1 times.

Post Reply

 Re: Cast iron stack leak
Author: NBMT91 (NJ)

As strange at it seems, everything indicates that the water is seeping "up" out of the joint. Is this completely unheard of? Impossible?

Post Reply

 Re: Cast iron stack leak
Author: kingshakabobo (IL)

You definitely see more water after the test?

I wonder if there is a blockage there holding water enough to seep out the joint.

Does rust produce capillary effect? I did a quick google search and it appears it may. The first result was some engineering report that appears to discuss that phenomenon. But I didn't read it.

If you are sure that's where the water is from and not from, say, a roof leak, I would change it out. Or do the quick fix described above if you don't have the desire to cut cast iron around water lines.

You are only looking at a few bucks and a trip to the big box store. Ahh, who am I kidding - Me: 3 trips to big box and a trip to the neighborhood hardware store and then a trip to the plumbing supply house. And a stop for beer because I'm aggravated.

Post Reply

 Re: Cast iron stack leak
Author: sum (FL)

Have you tried simply using a blunt chisel and carefully tap the lead all the way around and see if that makes any difference?



Edited 1 times.

Post Reply





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