Last Updated on 8 months by Christopher G Mendla
I replaced the galvanized 1 1/4″ drain pipe with PVC while fixing a clogged drain and vent stack in my upstairs bathroom. In the process I came across a stuck reducing bushing. In the process of trying to remove it, I broke it. I was able to remove it without damaging the threads in the T fitting.
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The Problem
The bathroom sink drains into the vent stack. A clog was blocking the sink and the drain. I wanted to replace the 1 1/4″ galvanized drain pipe with PVC so I could add a cleanout for the vent stack.
The vent stack had a T fitting with a 1 1/2″ female thread. There was a 1 1/2″ to 1 1/4″ reducing bushing and then 5′ of galvanized 1 1/4″ pipe.
The galvanized pipe unthreaded with relative ease. That left the reducing bushing in the vent stack T. When I tried to remove the bushing, it deformed and broke.
The image below is of the T showing the condition of the threads and the broken bushing. You can see the break at about the six o’clock position.
The problem was that the pipe dope had become rock hard over the last 70 years essentially cementing the bushing to the T.
I didn’t want to use a torch as the studs are thoroughly dried out.
Replacing the T would have been a major undertaking. Below is another image of the broken coupling
Removing the bushing
In order to remove the bushing I had to CAREFULLY make two cuts with a sawz all. I made the cuts at about the six and eight o’clock positions. The trick is to cut enough to cut most of the way through the bushing without hitting the threads of the T.
The sawz all cuts very fast through the bushing. It takes a very light touch to get it right.
You could also use an oscillating cutting tool.
Once I made the two cuts, I was able to grab the piece with a pair of water pump pliers and remove it.
BE CAREFUL – Don’t let any pieces fall into the drain.
After the small piece was gone, I was able to crush and jiggle the rest of the bushing out.
Cleaning the threads
The threads had a build up of solidified pipe compound. I wanted to clean things up as much as possible so I could seat the PVC coupling as deeply as possible.
The image above is of the threads before they were thoroughly cleaned. Note that the pipe is not clogged, it just appears to be.
I used a combination of the following to clean the gunk from the threads. If i had a inch and a half tap available that would have simplified the process.
- WD-40
- A wire brush used for cleaning 1/2″ copper pipe
- A small wire brush on a dremel tool. If I had a 1 1/4″ wire wheel for the drill, I would have used that.
- A heat gun (Be careful with the wood framing)
It didn’t take a lot of effort to remove the compound. I then threaded an adapter that had a hex head on it. That cleaned the threads a bit more. I didn’t cut grooves in the threads as it was threading in completely.
The adapter succeeded in cleaning the female threads of the T.
At this point, I cleaned the threads with alchohol on a cloth to remove any WD-40. The T was now ready for the PVC threaded coupling.
Summary
I am VERY grateful that I was able to remove the coupling without damaging the T fitting on the vent stack. It took a little bit of time. Fortunately I was working in a closet so I had room to work.
The overall project of replacing the drain pipe involved a LOT of work, effort and time. However, the parts cost was minimal including some tools. I’m not sure what a plumber would have charged but my guess is upwards of $1000. The total cost for me was less than $100. Given that I am in between jobs, it was a good use of my time.