replacing a drain pipe


Old 04-14-04, 10:40 AM
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replacing a drain pipe

I have been trying to replace the drain pipe for the vanity in my bathroom. After I have attempted for several times, I still find water leaking out at the metal nut that holds the drain pipe to the bottom of the sink. I have tried plumber's putty and caulk, but with no success. It is frustrating! Is there a trick to install a drain pipe successfully so that it is leak-proof?

Thank you for time.

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Old 04-14-04, 06:42 PM
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There should be a rubber gasket that contacts the bottom of the basin, then a metal washer, then the nut. No putty, silicon, or any other sealant should be necessary, other than what you use on the top side where the drain assy. drops into the bowl. Clean all of that stuff off. It may be that you have a defective gasket, or that the bottom of the basin has a flaw.
Old 04-14-04, 07:32 PM
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Some brands are bad about making a good seal, I'd put some silicone where the gasket touches the bottom of the sink.
Old 04-28-04, 12:53 PM
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Leaky Drain Solution


I hear about this problem almost daily at my job, and experienced it myself a few years ago when I installed a new lavatory and faucet. After I give the information below, nobody calls back to say it didn't work.

The Cause:

Because sink manufacturers are now also making sinks with no overflows (mostly because of silly reactionary laws in California which no longer allow this safety feature) many of the drain manufacturers have started putting the screw threads up higher on the pipe fitting so one size can fit all. Because of this, the tapered rubber seal that is supposed to fill the space between the pipe and the sink drain hole is not able to properly fit against the pipe side.

Theoretically, when the nut is tightened, the tapered rubber is wedged tightly into this space to seal the opening, but it is not possible to tighten the nut hard enough to force the hard rubber deep enough into the threads on the pipe to completely stop water from seeping through. If you check, you will see that the water is actually leaking through the threads on the pipe, not around the outside of the rubber piece.

I believe this occurs in over 90% of drain installations, but eventually, the rubber will deform over time and fit in deeper, and minerals in the water will form a dam, so the problem usually goes away before people really notice it. But people like me who test everything right after installing it notice these things and have nervous breakdowns and say things like "idiots are in charge of everything."

The Solution:

With the drain fitting in place in the sink, and the seal and nut screwed way down, use your finger to fill the threads in the pipe in the area where the rubber will be touching them with 100% pure silicone caulk/adhesive. Then slide or screw the rubber piece back up there and tighten the nut enough so the rubber seals on the outside. Over-tightening this can damage some sinks over time so don't put a breaker bar on your wrench. You can use silicone for insurance on the outer side of the rubber too, if the hole in the sink has rough edges as they sometimes do.

Good luck with your project, and let us know how it turns out!
Old 04-28-04, 02:05 PM
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Silicone, Ron? YOU???
I'm having a stroke down here...ROFLMAO!
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Old 04-28-04, 03:39 PM
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Yea Mike

This is the only place I use silicone, there and when the sink material says not to use putty, i.e. if the sink is made of marble.

I got tired of getting leaks on the bottom side of the pop-ups, so I went to using silicone, no leaks no more.
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