Leak under sink

[Alec Sprinkle]

Greetings all. New member here. Very long story short, almost everything in our bathroom vanity is getting replaced. I have no knowledge of plumbing or anything, so youtube has been a help on the basics. Unfortunately, there's a leak now. I have a new faucet on a new countertop. The piping and pvc all seem fine. The drip is coming from where the faucet is mounted to the granite. I have that black nut tightened down as much as I can get with the basin wrench, and it's still dripping after a few moments. Only if the cold tap is flowing, though (from the sink, not the shut off). Is the faucet malfunctioning? I was planning on removing the faucet and taking it back, but the nuts holding it on are plastic and the tightening pieces are broken. I can attach pictures if that helps.

Question: Do I need to replace the faucet? How do I remove the nuts? Can I just caulk where the water is leaking out on the underside? Will water pool inside the faucet and mold? Will I ever stop hitting my head on the sink? Sorry my questions are probably dumb. I don't know what to do.

 

[Terry]

An internal leak on a faucet isn't going away. It's best to repair or replace it.
Yes, a picture would help here. 800 pixels or less.

 

[Sponsor]

 

[Alec Sprinkle]

Here's a photo from the under the sink looking at the cold inlet. See how the places I should be able to tighten with are busted?

 

[Reach4]

Are you sure the leak is from up by the granite and not below that where the white PTFE tape is?

 

[Alec Sprinkle]

Yes. It's dripping from between the black piece and the granite.

The sink has to be on for about a minute or so before it starts dripping.

 

[Robert Berg]

You might want to check to make sure the faucet handle(s) is tight, especially if it's a single handle faucet.

 

[Alec Sprinkle]

It's two handle. I'm attaching a photo of it. It's a Kohler Lilyfield faucet.

 

[Michael Young]

take it loose. hook up the supply tubes. Hold the assembly over a bucket and investigate carefully. you'll find it. If it's a brand new faucet, take it back and trade them for one that doesn't leak