So I have the OPPOSITE problem most have.... I can't seem to get clean out covers installed. I am new owner of an old (100 yrs or so) building, and the waste line has two clean outs flush with the concrete basement floor. We recently had the waste lines surveyed and video recorded. One cap was barely on and was damaged, the other cap was a plug pounded into a lead sleeve inside the threads of the old pipe. The survey guys removed the old plug (by destroying the lead sleeve) and gave me two new 3" brass caps for me to install. The clean outs are clearly the same size as the 3" brass caps, but they only go in a short way before seizing (as if unmatched threads). I cleaned both iron clean out threads with a wire wheel on a rotary tool to ensure clean threads. Both still start to go, then seize as if improper threads. So I went to local hardware store and find PVC clean out caps that appear to have slightly different thread pattern and figure I'm all set now. No luck. The PVC caps won't even engage the threads at all. I'm starting to think the lead liner and plug is a clue that perhaps I have proprietary threaded iron clean outs from ages past that no longer have caps that fit. Any thoughts or advice?

One clean out is actually about 1.5 inches below the slab floor, and I was hoping to add a short extension to raise to floor level and cement around to make flush.

They COULD have fine threads but if so you could tell the difference. Usually the problem is that the cast iron is just rusty and you have to use a die grinder to clear the threads to the bottom of the "V". The ones with the lead were "fit all" plugs which either screwed in, or were pounded in. They were typically used when the cast iron thread was unusable for one reason or another.



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I have cleaned the rust off of both threads using a Dremel tool with wire wheel. Should a different wheel be used? Also, both caps turn about the same amount before seizing. I compared the thread imprint on a portion of the old lead liner to the new caps and they look close.

Is it easy to find fine threaded clean out caps to try?

Anyone trust and use the lead sleeve and plug method?



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quote; Is it easy to find fine threaded clean out caps to try?

Actually, it is impossible, because I have not seen any in the past 50 years.Lead is NOT perfect, but may be as good as you can get. They are seldom 'leak proof" just because the way they are made.

your options may either get a die grinder and fix the threads like hj said.... or use a lead fits-all... or a Sioux Chief Mechanical Test Plug Test Titan. the last 2 options should work but maybe not 100% if there is a backup.

any pics??

Test plugs seldom seal into a threaded opening.

You think a lead fits-all works a little better than a test plug, hj?

It WILL conform the threads, which an expansion plug CANNOT.

Try adding something to lubricate the threads. pipe dope, some wax from a wax ring, teflon tape. sometimes just reducing the friction will help a lot. Don't use food grease, it tends to destroy cast iron over time.