New sink install - leak issue


Hi all
I recently installed a new bathroom vanity, sink and faucet. I am getting a small leak at the point where the large nut tightens the drain assembly onto the bottom of the sink, compressing the black washer onto the bottom of the sink drain.
I have seen sink installs before, checked the net for hints, and even did a couple quite some time ago. I double checked the sink/vanity that was removed from the space, and also on line, so I know the washers on the drain assembly are in the right order. The drain flange has a good ring of plumbers putty under it.
The sink itself is an ornamental handpainted model, and may have some slight irregularities at the sink drain. Because the sink is somewhat more delicate than the standard white porcelain models, I don't want to risk overtightening the nut.
So what I am hoping to get are pointers on what the plumber-savvy folks would do to handle a leak on the underside of the sink drain? Can I add a thin bead of plumbers putty where the black washer meets the sink, in an attempt to fill any irregularities the washer can't handle? I am reluctant to use silicone at that point, just in case it isn't successful and I have to dismantle it again.
Thanks for any tips
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I think you have the right idea with the plumbers putty.
Hank
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gwandsh wrote:

    Drain pipes have been a problem for me as well. What I have found is that you need to tighten the connections as little as possible at first. If they leak, then tighten them some more. Over tightening them does not stop a leak like working with steel pipe.
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EXACTLY what he said!
If you've already cranked down a lot on the nut and compressed the cone washer then consider it shot even if it looks OK.
That large nut under the sink should be tightened as snug as you can by HAND. If it leaks then tighten with pliers/whatever ONLY 1/6 turn (a flat on the nut). Check for leaks and repeat if necessary. Should not take a whole bunch more after that. If it does then there is something wrong with the surface where the cone washer meets the sink. Once I feel it's not leaking I fill the sink to the top and let it rip.
Plumbers putty is only suppose to be put on the top between the recess of the sink hole where the drain flange sits.
Any chance you overtightened it already?
You would really have to overtighten the heck out of it to compress that rubber cone washer enough to crack the sink.
It does have a CONE washer?
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One rule I follow when mounting a drain tail pipe in a sink. ALWAYS, make the putty donut thicker/larger than needed. Mine may be 3/8 - 1/2 inch thick. When the nut is tightened below the excess putty is squeezed from around the drain edge ( easy clean).
To little putty will possibly cause a leak along the tail pipe and travel under the sink.
First guess? Pull the pipe and try again.
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Oren wrote:

You shouldn't need any putty at all on a sink like that. The gasket with the hump goes up against the sink and pipe and plugs the hole around the drain when you tighten the nut. No putty needed if you did it properly. If the OP has leaks then it should be taken off and examined, not gooped up with putty and silicone. Replace the drain pipe, gasket, nut as necessary. Make sure the sink isn't defective or irregular around the drain hole. If so sand or file it smooth or replace the sink too.
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wrote:

Agree 100%. Sometimes we just don't follow the rules.
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wrote:

From the OP
My suspicion is that the "hand made" attribute of the sink has left it with some small irregularities at the drain, which are causing the humped (I assume aka cone) washer from sealing it effectively.
I have taken it off an re-examined it several times. Also got a brand new drain assembly from the plumbing supply. This is a higher end assembly, from a biz contact in-the-know at the supply location. The brand new assembly displayed the same leak at the same spot, so I lean towards the sink outlet being the issue.
'Fraid replacing the sink isn't an option. I won't bore you with the story, but an entire bathroom remodel revolves around finding this special sink first, and ending up re-doing the whole bathroom to match it. But perhaps the sanding of the outlet is more viable than using putty to fill irregulariites. I will look at that option when I get there this weekend, although getting at the sink outlet (now installed) will be tricky.
Cheers
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gwandsh wrote:

If you've got water that's any kind of hard, put a bucket under the sink for a few days and see if the leak heals itself.
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Thanks all for the responses. To fill in some gaps in the info: I have already re-installed this a couple of times. I use a pretty thick roll of plumbers putty. Perhaps tightening has squeezed out too much. I *did* try the finger tight nut solution. I then tried tightening a half turn and re-testing. After 4-5 half turns, I stopped in fear of damaging the sink. To Red Green (one of my fav shows, BTW): If I have over-tightened the black washer (I assume that's the "cone" washer, it does have that shape), does it need to get replaced before I try to re-install? Can I use some plumbers putty along with the cone washer to make the seal on the underside of the sink?
Cheers
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wrote:

I'm no plumbing person. Just relaying my fu...errrr...fixes. I've had experiences where I retried doing the tightening sequence with the same washer. Rarely it corrected it. Replacing it and following "the rules" frequently fixed it.
For clarity and a better chance at someone helping, were are talking about a leak at the red arrow in this pic right?
    
http://i47.tinypic.com/apfhw2.jpg
Plumbers putty there I wouldn't have much confidence in. If you are really desperate and at a loss go with silicone. I was once in that desparation position. Did not have silicone, there is no pressure being a drain but I did have <time for the group to laugh here> and open tube of roofing cement handy. Sink underside black, cone black. Never leaked afterwards.
And you thought I was kidding when I said I was no plumber :-)
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Red Green wrote:

No, but you're plenty smart.
Roofing cement is designed to stop leaks, right?
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That was the thought at the time...
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gwandsh wrote:

You don't need a seal on the underside, it should seal on the top - inside the sink. The nut is just to pull the inside drain flange down so the inside seal is made.
You are talking about the tail piece, right? The metal tube with a flange that fits through the hole in the sink and is attached to it with a nut? I ask because you mentioned a cone washer...never seen one of those used in that situation. Flat, yes; cone, no. Cone washers are used when hooking the P-trap to the tail piece.
--

dadiOH
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wrote:

How does the overflow water get into the drain in sinks with an overflow?
Through the holes in the side of the tailpiece pipe that sits inside the sink. Not visible once connected. The overflow runs in a hollow sink chamber and goes into the tailpiece holes. When the sink is draining some water can also come out of the holes and enter the bottom of the chamber...where the cone washer is.          Hole to the left of the white washer.     
http://www.plumbingsupply.com/images/delta-rp6463-popupassembly.jpg
    Holes above the white washer.     
http://mrdirectint.com/sinksandfaucets/images/options/vessel_popup_drain.jpg
    And another     
http://common3.csnimages.com/lf/2/hash/2724/432798/1/Exquisite+Pop-Up+Umbrella+Drain+with+Overflow.jpg

Cone washer pretty common. Not always used I guess. Just like all sinks don't have overflows and all popups don't provide for overflow.
http://common4.csnimages.com/lf/2/hash/819/1063199/1/Premier+Pop-up+Drain,+Exposed,+with+Overflow.jpg
OP:
Does your sink bowl have an overflow hole? If so, did you use a popup with an overflow? If you didn't, once water enters the overflow chamber it will fill with water and just sit there. Not good.
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Red Green wrote:

My bad, my brain was on kitchen sinks.
--

dadiOH
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The bottom washer/nut must be tight also, since the sink overflow comes into the drain below where the drain stopper fits into the sink opening.
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wrote:

Thought I would follow up and finish off this thread. I finally contacted my much trusted plumber/contractor all-around-good-guy and he came out on a service call. He checked my work over, dismantled the installation, added silicon and snugged it back up. End of leak.
When I told him I had been reluctant to do that because of the "permanency" of the fix, he assured me that if necessary, the drain can be dismantled and the silicon will peel off quite easily.
So the bottom line is, if nothing else works, sometimes the obvious answer is the right one.
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On Tue, 29 Dec 2009 13:45:36 -0800, gwandsh wrote:

Was the drain pipework supplied with the sink? If not*, are you sure there's nothing stopping the nut from tightening further, other than the sink itself? It's just a stray thought, but I'm not sure if anyone's mentioned that possibilty yet...
* or even if so; maybe there's damage to the threads on the part that the nut screws on to, so it feels tight before it really is.
cheers
Jules
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