Kohler fills every 25 minutes -- is a bad flapper to blame?

Hey all,

For the past few weeks, my Kohler toilet fills every 25 minutes or so, and stays on for about 15 seconds. I did some online searches, and the consensus seems to be that the problem is the result of a bad flapper.

I turned off the shuttoff valve, and inspected the flapper, and it still looks good to me. It says "Coast Foundry Made in USA" on it. Is there any way for me to know ahead of time if this problem is the result of the flapper being bad, or should I just go ahead and replace it?

If I should replace it, can anyone point me to a tutorial?

Thanks so much.

On the previous post I mentioned that I frequently use food coloring die to test flapper valves
Dump some food coloring into the tank and watch the bowl, if it slowly starts to change coloring then there is a leak at the flapper valve.
Michael
Sac City Plumbing

Thanks for the response, SacCity. The sound I hear coming from the toilet is very similiar (although a little more muted) to what I hear when I gently push the handle down, so I'm pretty sure the problem is with the seal at the flapper valve. My concern is that the flapper seems fine, so I'm not at all sure buying a new one and installing it will help.

I just got done reading the thread at:

https://terrylove.com/forums/showthread.php?9172-Kohler-1-pc-Rialto-flapper-leaks

That makes me even less sure.

It wold appear my model is slightly different than the one in that thread, because I don't see the rectangular thing in the picture. Instead, my model has a much smaller circular tube. I'm not sure what my model is.

On the inside of the tank I see K4620. Is that the model number? If so, does anyone have any experience with the kind of problem I'm describing?

A quick addition: I just did the food-coloring test, and yes, the dye is showing up in the toilet bowl.

EVERYONE has had that experience, but we usually take care of it before it continues for a "few weeks". Flappers that "look good" can leak just like those the look bad, they just don't leak as fast. That picture you looked at is a "specific model" not the same as most flappers, which you probably have.

OK, good to know. I don't see the model number stamped on the flapper itself. Do I just go to my hardware store and ask for Coastal Foundary flapper?

Also, it's not clear to me exactly what gets removed and how. Does the styrofoam thing above the flapper come off and get replaced, too? Does anyone know of a YouTube video or other tutorial that shows how it's done?

The styrofoam float is there to help in the timing of how long the flapper valve stays open. I'm pretty sure it comes with a new flapper, which also has the chain on it.

OK, great.

Thanks to everyone who took the time to respond. It's a real help to this plumbing newbie.

If anyone has any thoughts on exactly what kind of flapper I should get, or any tutorials on how to remove it, that would be awesome.