I am installing a new granite/sink combo from Lowes and a Pfister pop up drain. No matter what I do it is not seating itself under the sink and is allowing for a small leak at the rubber gasket. I have tried plumbers putty and that did not fix it. My next step is to use silicone. Anyone done this before? Will it eat at the rubber gasket and cause more problems later?

n_touch said:

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I am installing a new granite/sink combo from Lowes and a Pfister pop up drain. No matter what I do it is not seating itself under the sink and is allowing for a small leak at the rubber gasket. I have tried plumbers putty and that did not fix it. My next step is to use silicone. Anyone done this before? Will it eat at the rubber gasket and cause more problems later?

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Do you have the correct sized drain tail pipe for the sink?

Some of the cheap or poorly designed versions are really hard to make not leak. It may also not fit the sink well from a depth perspective. So if it is a typical finish on the visible parts, you might try a different one from the store.

Did you seal on the top side of the sink? I always liked to use clear silicone rather than plumbers putty.

Just using the one from the box that came with it. Never run into a problem like this before.

The top is sealed by a gasket that comes with the drain and no putty or silicone is needed on it.

The water seems to be falling through the overflow holes and the leaking out of the bottom rubber gasket that seals to the sink. I see that some have used putty there and I tried that but it still let a little through.

n_touch said:

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Just using the one from the box that came with it. Never run into a problem like this before.

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Okay, just checking. I had an issue with one of our bathroom vanity sinks doing the same thing and I just used some silicone caulk to seal it. Been a couple of years ago and it's (knocking on wood) fine.

Is the flat surface of the sink perpendicular to the drain?

I had one on a tub that was slightly skewed. called manufacturer and they said to return or sand it to be perpendicular. I sanded it until contact was even on all sides, worked fine after that.

Oddly enough I've been battling the same problem this weekend. I tried silicone and it still leaked. I then had to scrape all the silicone off everything. I bought a new lower gasket ($1.49 at Home Depot) replaced that and added a ton of plumbers putty to the top drain as well as around the lower gasket, snugged it up all good and tight and finally problem solved. I also put Teflon tape on the threads there the drain screw on as well as the lower but. Good luck with yours, it's been a PITA.

Got it fixed (knock on wood) yesterday. Looks like I was tightening to much and twisting the gasket. Been in since mid day yesterday with no problems.

As you discovered, those gaskets get kind of twisted up. I installed two Pfisters that both did the same thing, the trick for me was to get the gasket really snug and level before tightening. You'd think they would put some tips in the manual or something, but I guess not.