I recently had 2 bathroom faucets replaced, there is no leaking underneath the sink when running the water, but if one faucet gets wet, i.e. by rinsing bathroom cleaner off the faucet with water, it leaks underneath the sink at the top of the water line -

Only one faucet does this, the other is OK - nobody can figure out why,

Could it be a missing or damaged gasket? No silicone caulk inside the faucet? There is silicone around the base of the faucet... One person said not to pour water on the stem rod, I did an experiment and only poured a little water on top of the cold water faucet and it leaked - somehow water is penetrating and leaking and I can't figure out why.

Thank you for your assistance, I'm at my wit's end...

There should be some type of seal under the faucet base. A plastic flange is usually provided with the faucet and is tightened against the sink by the nuts under the faucet. Since the sinks are not perfectly flat, you may need some additional sealant.

Before plastic gaskets we made a small rope of plumbers putty and set the faucet in that. Silicon Jel works also, Good luck, Tom

Thanks so much for replying, I emailed Delta Faucets and they said there should be silicone caulk around the base of the faucet, well, there is...

I conducted an experiment, poured some water not on top of the faucet but around the base of it, and the water leaked underneath... so I'm guessing something is not right inside the faucet...

The plumber installed both faucets, one's OK, the other is not.

Hopefully he can figure it out... thanks again