toilet flapper problem

All flappers are not created equal. Purchase a quality brand and hopefully the dimensions will be accurate enough to seal. Korky sells the red flappers that usually work well.

Are you certain it is not the tube that goes into the overflow tube being too low. If the end of the tube is below the water line it will siphon slowly causing your symptoms. It should not stick into the overflow tube by more than a half inch.

The only flapper I could make work in my Kohler one piece was the real Kohler flapper and even then the chain adjustment is critical, within a link or two.

I had the same problems, right off the bat, I didn't do the vaseline thing, since that kinda weirds me out. ;) I found the flapper was 'crooked' didn't sit right. I seemed that it was a manufacturing defect. I didn't return the flapper, since it was part of a kit, and by the 1000'th time the tank constantly refilled, I took it out and stompted the life out of it.

I got a new flapper, I stick with the same manufacture as the seat, since they were meant to be, and it worked.

Now this is what happened to me, you might need to get a replacement part.

later,

tom @

FWIW, I agree with the other guys. Replace the flapper, even though it's new. They're cheap.