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lead oakum joint not tight

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I'm doing a bathroom remodel. The old bathtub drain used 2" galvanized pipe that threaded into a cast-iron tee. The tee is sideways; the lower branch is a lead oakum joint connecting to a larger tee on a 3" drain pipe. The side of the tee was the horizontal 2" galvanized pipe going to a trap and then to the tub drain. The upper branch of the tee goes to a vent. Earlier, the upper branch was converted to ABS with a thread adapter.

Fortunately, the horizontal 2" galvanized pipe would unscrew from the side of the tee. However, there was not enough room for the trap to rotate, so I cut the horizontal 2" pipe with a sawzall. All the shaking apparently loosened the lead oakum joint at the bottom of the tee where it connects to the larger tee. If I tug on the upper tee, I can see relative motion where it connects to the larger lower tee at the lead oakum joint.

How can I repair this? Can I just tamp the lead oakum?

I suppose I could pull apart the lead-oakum joint and remove the cast iron tee. Then use a rubber boot on the lower tee and re-plumg the whole thing with ABS.

Do I need to repair this? The fit is still tight, and given that the drain flows freely, maybe it won't leak. But it doesn't seem right since these joints are tested with a few feet of water pressure.


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· Registered
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Discussion Starter · #2 ·
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Actually, what I called the lower tee on the 3-inch drain line is a reducing wye, since the 2-inch branch that carries water down into the drain directs the water in the right direction. The vertical 2-inch "intake" of this reducing wye is the location of the questionable lead-oakum joint.

If I cannot repair this joint, I could pull it apart and try to interface to the cast iron with a rubber boot. However, the cast iron at this point has a "lip" that is 3.75 inches in diameter and then reduces to 3.5 inches in diameter. I could cut the lip off the cast iron pipe (sawzall again) and hopefully find a rubber boot made for 3.5 inches.

Or maybe I should add supports for the cast iron pipe on either side of the reducing wye and use rubber boots to install a new ABS reducing wye so I can re-plumb.

Since the floor is opened up now, I ought to go for the most reliable repair.

Any recommendations?


· Premium Member
12,890 Posts
Before you start hacking apart your fittings, attempt to repack the oakum joint. Use a blunt chisel and hammer to tap the lead back down. Work your way around the fitting. When it appears to be tight, fill your tub with water, pull the plug and check for leaks.
You can also find an old school plumber to redo the joint for you. Cutting cast iron hubs may be more work than you think.
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