water torture

In the process of repairing a leaky toilet supply line, I replaced the shutoff valve. I fixed the leak at the supply line, but now I have a new leak. I get about 1 drip every 30 seconds coming out of the threads of the shutoff valve, where it screws onto the pipe coming out of the wall.

Shutoff valve has a 3/8" FIP (female iron pipe?) connection to the supply pipe. I tried putting the old valve back on, but that now leaks too.

I have tried teflon tape, up to 4 wraps. I have tried pipe joint
compound ("with teflon"). I have tried compound-tape-compound. Can't
seem to get it to stop. I have made the thing pretty tight. I could
make it tighter, but I am afraid of breaking off the pipe inside the
wall, and then there would be no cold water upstairs, and someone
would have to make a hole in my tile wall to fix it. That would be
very bad.

Is this pipe threaded into a fitting in the wall, or is there a sweated connection in there? The pipe chrome-looking, male-threaded. Is it iron, brass? Don't know. Looks like there is a pretty good-sized nick on the very end of the pipe. I don't believe I damaged the pipe, so that nick was probably there before. Why it didn't leak before is a mystery to me.

Your advice is appreciated.

Curt

Try wicking and pipe dope.

It's like thread. They probably sell it a a plumbing supply house.
Wicking then dope or dope then wicking. I don't think it matters.
What matters is where it is leaking. The water may be traveling from
someplace else. It's probably a chrome nipple into the wall. I wouldn't
screw with that, yet. JMHO.

wicking/nipple

A remodeler friend supposes that I need a new nipple -- just unscrew the old one, tape+dope the new one and screw it in. He makes it sound easy, but I feel like I am starting to replace my entire plumbing system, starting at the toilet and working my way out to the street. (What happens when the connection inside the wall leaks???)

You suggest "wicking" -- I have seen references elsewhere to "wicken". What is this, a brand name? What kind of stuff is this?

leak

As you look at the 3/8" nipple coming out of the wall, wind your teflon tape clockwise and then use teflon dope. Do it over again.

If the nipple is chrome then it's a brass nipple and should not be rusted out.

Before you attempt to put that old valve back on, look at it real good because it could be cracked. Please don't over tighten.

If your water pipes are copper, then that nipple shouldn't be galvonized.

Wicking is what was used a long time ago. Boiler installers used it. It was also used on the old wall hung toilets at the 2" flush ell, under the jam nuts. When it got wet it would swell.

And it wouldn't be used on a 3/8" nipple.

Replaced the nipple, problem solved. Thanks for the advice.

Glad it didn't bust in the wall.

wicking

"Wicking" is an old plumber's trick. The work comes from "Candle wicking" which is the string used for the wick in a candle. When we did not have a ball of wicking, we found a handy O'Cedar string mop and used one of its cords, which were almost the same thing.