We became alerted to the problem when the toilet began "running" every couple minutes. We realized the tank was draining when we turned off the water to the toilet and the tank emptied. First we replaced the valve system. The tank continued to drain. Then we replaced the flapper. Still it drained. Then we removed and replaced the seal at the base of the flapper (the replacement appears to be sitting properly) and it's still draining! There are no leaks in the tank that we can see and there's no water leaking outside the tank. With all new innards and an apparently intact tank it seems like our problem should be solved, but it isn't.

Hi Twoleftfeet...

If you have replaced all these parts and are still having trouble then the only thing left would be to replace the entire FLUSH VALVE ASSEMBLY.

Here, at times, a new flapper simply won't mate up to an old flush valve assembly and you need to replace the flush valve assembly to finally resolve the issues.

At my plumbing company, we never just replace a flapper... always replace the flush valve as it really doesn't take someone with experience very long to do and a call back over a leaky new flapper just isn't worth it... ;)

Try this fix and let us know how you make out, OK?

Mark

Thanks, Mark. Actually, we have replaced EVERYTHING within the tank. I guess I failed to make that clear.
Latest question: We had assumed that the tank was draining into the toilet bowl, but it's not. We placed a strip of paper along the back upper rim of the bowl (where the water comes from when you flush) and that stayed dry while the tank drained.
So, we have all new parts in the tank that seem to be correctly installed and the tank continues to drain and we don't know where the water goes. Maybe it's time to move.
Twoleftfeet

TLF...

You changed the entire FLUSH VALVE... see image?? Let me know, OK?

Mark,
Yes, we did.
We now have a new American Standard #4 flush valve with new "bolt hole seals" and new "sub-assembly."
We also used a new Fluidmaster Universal Toilet Fill Valve.
Truly, EVERYTHING has been replaced.
We think now that the water is leaking out between the rubber ring and the porcelain at the flush valve.
What do you think? Should we try silicone around the seal? (We tried silicone around the OLD flush valve and that didn't work.)
Thanks,
Twoleftfeet

Tlf

OK... silly question, BUT, did you install the flush valve so the rubber washer supplied with it went on the INSIDE OF THE TANK (tank to bowl gasket goes on the outside)? How tight did you tighten the flush valve nut... needs to be pretty snug to snug the washer down (my guess is pretty tight because you removed the old one, right)?

The only other thoughts I have focus around either a cracked tank or a cracked flush valve assembly.

Here's what I would do: I would take a really dark blue food coloring and I would pour 25 drops into the tank and let it sit until the blue water disappears from the tank and then shut off the water and drain the tank and check it for cracks (the dye will color any cracks deep blue) or deep stainging at the washer area.

If you can't find any leaks/cracks then I would reinstall the flush valve (or a new flush valve) and see if that will finally put this to bed... ;)

Let me know what happens, OK?

I've been too depressed to report back! Everything seemed to be installed properly, so we took your advice and added 25 drops of food coloring to the water in the tank (which quickly revealed that the water was draining into the bowl and not magically evaporating as it had seemed). When the tank emptied there was an amoeba-shaped fine line of color on the bottom of the tank, a roughly 4 by 2 1/2 inch hairline crack that hadn't been visible to the naked eye. As the crack forms a sort of enclosed oblong rather than a line, we realize that, rather than trying to seal the leak, it's time to purchase a new toilet. All those new parts and all that effort down the drain, so to speak. But thank you so much for your counsel, Mark. Otherwise we'd still be trying to figure it and out AND still flushing with a bucket into the foreseeable future.

Sorry to hear, but glad you finally have your answer here. I appreciate your popping back in to update me!

Have a good day!