New sink is leaking

Hi, I'm having problems stopping a leak in a new sink in my 1/2 bath. I put in a cultured marble vanity top/sink combo and a Delta faucet. I previously did the same type of install in my other bathroom with no trouble.

The leak is aboove and below the nut holding the rubber gasket in place. I've tightened that down about as far as it will go, but I still get a decent-sized leak. Do I need to seal the threads with tape or pipe dope or should I just tighten the nut a little further? TIghtening it isn't making a big difference for some reason. I did seal under the pop-up flange with clear silicone, for what it's worth.

thanks,

Jim

Unscrew the drain and remove the caulk.
Roll a roll of fresh plumber's putty in your hands about the size of a pencil and wrap it around the hole under the drain lip, and tighten the drain back down on it, and clean away the excess putty (save it in the can).
Good Luck!
Mike

Unfortunately that drop of water is traveling down the threads. I like to take a ball of putty and rub it into the threads,, removing all excess but the threads are now blocked from water travel. You will need to take it completely apart to do this.

Mike--I tried taking it apart and using plumber's putty instead of silicone. I also put some plumber's silicone grease on the rubber gasket. This definitely made the leak smaller, but it still IS leaking.

Jimbo, I think I will try your method. In looking at the design of the pop-up, I don't think the problem is the seal around the drain flange. There are large holes in the part of the flange that screws into the pop-up assembly. This is a strange design, in my opinion. Water will go through those holes, bypassing both the plumber's putty and the rubber gasket. You can see the holes in my attached picture--they let water right into the threads, where it seeps through. Delta does not give instructions to seal the threads in any way.

Use the Silicone under the flange for cultured marble .

Plumbers putty has oil in it that will cause problems with the marble.

For the leak below, you can loosen the nut below that pulls the rubber seal up against the sink, and rub some putty into the threads there.
Then shove the rubber seal up and tighten the nut.

The large holes in the upper part of the drain assembly are for the overflow.
That small hole near the top of the bowl prevents overflowing the countertop.
The water has to drain somewhere, through those large hole and down the drain.

I put a small coating of pipe dope that is ok to use on PCV on the rubber gasket where it meets the sink and putty on the threads as mentioned above.

The putty on the upper flange is only for a cushion; it doesn't matter if water goes through there, because under the flange is the chamber where the water from the overflow enters the drain. It is the seal at the botom of the sink which is important. It is the threads on that lower peice that need to be sealed, not the threads on the chrome flange.

Thanks for the help, guys! I think I got it this last time with putting putty on the threads. It doesn't seem to be leaking now. My sink is now ready for the Easter crowds!