Lav Sink Drain Flange- Can't stop the leak question

[Bird Doo Head]

Hello All!

I purchased a new 4" centerset for a lav vanity sink. When I removed the old drain body, I noticed that the beveled washer that is sent up to the sink outlet via the lock nut was upside down. The flat part was facing up at the sink bottom, instead of the bevel going into the hole in the sink. (In case I am using the wrong part names, a drawing is attached.)

When installing the new faucet's drain body & flange, when the bevel was facing up as received, the drain leaked quite a bit. I experimented around with ensuring the items were centered & tying various amounts of tightening on the lock nut. It still leaked a lot. I bought a new beveled washer in case I damaged the one that came with the faucet. Again, no luck with bevel up.

Next, I removed the sink (American Standard of some sort of glazed ceramic or porcelain material) flipped it over and looked in the drain hole. I can see that the outlet is somewhat mis-cast. It's also rough and not glazed. Experimenting with the beveled washer in my hand, I could see it can't seal properly in the hole with the cone side up.

I re-installed the drain body with the washer upside down, as was the faucet's drain that I removed. the flat part is touching the bottom of the sink. The bevel is touching the locknut.

Now it leaks a tiny bit. The water appears at the bottom of the lock nut. Again I experimented with various lock nut tightness. No luck removing the last, tiny leak. I tried PTFE tape on the locknut threads. No luck. I also thought about trying plumber's putty or duct seal on the top of the gasket, but wisdom made me wait and ask the experts here.

Have any of you ever encountered such a problem? Do you have any hints or suggestions that I may try?

Thanks For Sharing your knowledge & experience. It's appreciated.
Paul

 

[johnjh2o]

use the putty on the top side.

 

[Twowaxhack]

Use some silicone on the rubber gasket and on the threads. Don’t over tighten. Done.

 

[breplum]

Specifically silicone just on the threads to block spiraling of water where the washer makes contact.

 

[Bird Doo Head]

Thank You each for taking time to reply with solutions.
For Silicone, I saw 2 kinds: Plumber's Silicone & Silicone Caulk. The Plumber's Silicone is like a paste & the caulk is caulk. Which one do you recommend?
Thanks Again,
Paul

 

[sawguy]

100 percent silicone.

 

[Bird Doo Head]

Thank You all again for helping. I appreciate it much.

I tired silicone caulk just on the threads, letting it cure for more than a day. It still leaked, so I must have done something wrong. I tried again with caulk on the gasket and threads. The same results arrived, so silicone karma is apparently against me.

I was called away for some days, but hopefully I can try again in a day or two. This time I'll try a new gasket and plumber's putty that Johnjh20 mentioned. I'll be sure to report back (with happy results, I hope).
Paul

 

[Twowaxhack]

Post pics of what you’re working with.

A pop up drain for a lavatory with an overflow doesn’t seal against leaks underneath by means of putty under the pop up flange.

Putty under the flange allows the basin to hold water when the stopper is engaged.

The overflow entry is below that flange, so the Mack gasket is what seals against leaks below.

 

[CT18]

Is it a plastic pop up that you are putting on. If so throw it out and get a metal one. I have had tons of issues with those cheap plastic ones

 

[breplum]

Like Twowax describes, a leak at the bottom of the porcelain can only come from two sources, the inner threads of the drain tube or the place of contact with the rubber washer (Mack gasket or beveled washer).
So, don't go buying special putty, you either missed silicone at the point of contact where the threads contact the washer or it is something very bizarre that none of us has ever encountered.

 

[Bird Doo Head]

Problem solved (the long way).


Step One-
I forgot that I own carbide files. The half-round one worked well to smooth the bad casting on the inside, vertical part of the sink's drain hole. It kind of disturbed me that American Standard didn't glaze in there, where water pools, so I treated it with quatenary ammonium that I have and, when dry; cold glazed it with a few coats of nail polish. (Want to keep the anaerobic bacteria from growing in the ceramic)

I thought I had the leak solved, but a small amount if water still leaked. I changed out the included gasket for a real mack gasket. The original that came with the faucet was a tall cone. The replacement is a sorter cone with a flat part at the bottom. (It actually looks like the mack gaskets we used to use for certain electrical hubs.) I made a plastic washer to go between the bottom of the gasket and the nut so the gasket would not twist with the nut.

Step Two-
The drain part stopped leaking, but the threads around the nut leaked. No PTFE tape or pipe joint compound or both combined worked. The plastic threads were just too sloppy-loose.

I took CT18's advice and got rid of the plastic pop-up drain in favor of a Made In USA metal one with a cast brass upper body.
Interestingly, the metal pop-up had the mack gasket like the one I bought and a plastic washer.

Step Three-
Enjoy the sink.

Thank You All very much for helping. I learned a lot and am now well armed with knowledge for my next faucet adventure.

Paul