argh! leaky sink stem

[Fritz57]

one of the faucets I put in yesterday is leaking from the drain stem.
sealed the stem in the basin with silicon.
I did not tape the thread on the black stem below the basin.
Nor the PVC, as I never have.

Water puddling in the blue oval, but no sign of water dipping down the black stem.
Seems like capillary action?
I opened and adjusted the PVC connects of the "P" and stem and did find one gasket a little out of place, but it's still puddling.

 

[TomFOhio]

Fill the sink up to the top and then let it out. That puts pressure on the drain pipe and will usually find your leak.
Dry the pipes first. Make sure you didn't forget the poly gasket that goes under the nut.

 

[Fritz57]

did double check for the poly. I'll give it a fill and drain.

 

[GReynolds929]

The gasket on the bottom of the sink looks deformed. That could let water leak through the threads. I would check that. I also always dope those threads on the pop up to seal them.

 

[Fritz57]

yea it does on closer inspection. As far as dope (don't have any), perhaps I should putty the top instead of silicon.
I wrapped the junction of the black into the 1st PVC with a little teflon. So far OK.
But I will do a "pressure" check as TomF suggested as well.