Leaky flush valve seat?
I have a Kohler Wellworth toilet that has an ongoing internal leak. I replaced the flush valve assembly twice (first with Fluidmaster, then with the exact Kohler flush valve assembly for that model). At the same time I replaced the tank-to-bowl gasket (black triangle). I also replaced the fill valve, but think that was unnecessary.
Even with all new internal parts I still have a problem. With the water turned off, the tank water level drops by half in just a 30 minutes. (If I leave the water turned on, I can hear a faint hiss of the fill valve working.) I also put food coloring in the tank and it showed up in the bowl within ten minutes. The level in the bowl stays the same.
All I can think of is that ceramic flush valve seat opening in the bottom of the tank is chipped or something, but I could not see or feel any roughness that would cause a leak.
Do I have to get a whole new toilet?
Thanks for any advice.