Kohler toilet tank emptying by itself

[oscar41]

Even after replacing with new transfer flush valve, tank empties slowly by itself--while water inlet valve is shut off. If water inlet valve is open, tank periodically refills. What should I look for now to fix this problem?

[HayZee518]

replace the flapper in the tank and make sure it seats itself with each flush

[JSullivan]

I agree, replace the flapper. Make sure you get the right flapper for your toilet though, "universal" flappers don't fit every toilet. And use Korky stuff, they actually work and have really good customer support if something doesn't work.