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-   -   Bathroom Sink Drain Leakage (http://www.diychatroom.com/f7/bathroom-sink-drain-leakage-14320/)

notaplumber 12-12-2007 08:19 AM

Bathroom Sink Drain Leakage
 
When installing bathroom sink drains I have almost always had a problem with leakage at the large rubber washer just below the sink opening. I'm referring to leakage between the sink bottom and the large rubber washer.

Somewhere I read that applying plumber's putty (not dope) to the threads of the large nut that compresses that washer will prevent leakage via the threads. Has anyone used that method routinely?

Also. would silicone rubber smeared on the rubber washer and perhaps also applied to the threads be likely to work?

majakdragon 12-12-2007 08:26 AM

I don't know how the putty would help, on the threads. I use a light coat of petroleum jelly on the rubber washer so the nut will not hang-up on it and twist while tightening.

notaplumber 12-12-2007 08:32 AM

Majakdragon that's the quickest reply I have ever got in any forum ever. Thanks.

I wonder if the underside of the opening in the ceramic sink should be sanded to provide a smoother surface for the rubber washer to make better contact with?

majakdragon 12-12-2007 09:11 AM

I always inspect around the drain hole for pieces of the material that may have gotten stuck there. Seen it too many times to ignore it. We all try to answer questions quickly, but sometimes we are not online when they come in. Hope the info helps. Good luck.

notaplumber 12-12-2007 09:16 AM

I just took a closer look at the sink I am presently working on. The edge of the circular opening below the sink appears to have a nick in it that might make it difficult to seal with the tapered rubber washer (too large a nick to be sanded out).

Many years ago I had a Moen rep tell me to try the rubber washer upside down and in that case I believe it worked. The flat surface around my sink opening is fairly smooth so I'll try that next.

redline 12-12-2007 10:49 AM

Quote:

Originally Posted by notaplumber (Post 80007)
When installing bathroom sink drains I have almost always had a problem with leakage at the large rubber washer just below the sink opening. I'm referring to leakage between the sink bottom and the large rubber washer.

Somewhere I read that applying plumber's putty (not dope) to the threads of the large nut that compresses that washer will prevent leakage via the threads. Has anyone used that method routinely?

Do you apply plumbers putty between the drain and the upper part of the sink?

notaplumber 12-12-2007 12:18 PM

Yes, I use plumbers putty instead of the furnished rubber gasket. However, any leakage there will simply go down the drain anyway, except for what might leak at the large rubber washer (if I understand correctly how this works)

jpplumber 12-13-2007 12:42 AM

I always use pipe dope ( I like true blue because it is smooth and not gritty) on my pop up assembly on the threads near where I expect the rubber to come into contact with the sink, and on the rubber itself. Water can trickle down the valley of the threads if you don't do this. Never have used putty except on the top side next to the stopper, but I guess that works too on the underside. I also started putting pipe dope on my pvc tubular drain washers and all my brass compression fittings on the ferrule. Can't remember the last time I had a leak.

notaplumber 12-16-2007 07:41 PM

There is a horizontal flat surface about 1/4 inch wide surrounding the bottom of the drain opening. I reversed the large rubber washer so that the flat side of the washer is on top. I smeared silicone rubber on that surface and wound some teflon tape around the threads of the drain body. My leak problem seems to be solved!

It appears to me that the large rubber washer (gasket) will always have a better chance of providing a good seal if the flat side of the washer is installed upwards. That way there is much more area of contact. So why do instructions always say to install that washer with the tapered side up?

majakdragon 12-16-2007 09:53 PM

The idea is that the bevel will pull down on the drain and at the same time pull up tight and make a seal in the hole as you tighten the nut.

notaplumber 12-17-2007 01:26 PM

The "idea" sounds reasonable, however if the circumference of the hole is not smooth and continuous then the bevel will be unable to make a seal.

majakdragon 12-17-2007 03:18 PM

AHHHH, if only everything worked as it should. LOL. You are right and sometimes you have to go another route to achieve the needed end.

Jimbob 01-04-2008 08:23 AM

Apply a liberal amount of good quality silicone sealant between the ceramic and the rubber washer; let it dry completely before putting on the trap.

This does the trick.


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