The tank is losing water, there is none on the floor, the toilet runs periodically to refill the tank, I have replaced the flapper, the float device already.

The tank is loosing water, there is none on the floor, the toilet runs periodically to refill the tank, I have replaced the flapper, the float device already.

Put food coloring in the tank and look to see what the bowl looks like in a few hours...

Put food coloring in the tank and look to see what the bowl looks like in a few hours....

Just did this at 2:44pm, will follow, I'm thinking it's the overflow tube that may be cracked. The last time I had this issue with a similar toilet I replaced the overflow tube but could never get the tank to seat without leaking and ended up cracking the tank, ending with a new toilet. I'd rather fix this one without the same thing happening again. Thanks

Sometimes the surface the flapper seals on erodes or gets damaged and a new flapper won't seal... trying to determin its not leaking past that first. Before you put the food coloring in... wipe the sealing surface with a rag and make sure a piece of crud isn't lodged preventing the flapper from sealing.

After 2hrs and 15mins there is a very slight trace of the dye in the very bottom of the bowl.

No change in amount of dye in the bowl, still very very slight trace only. This is after 4 hours with the dye in the tank

Sometimes it's a bad flapper but sometimes its actually the flush valve the flapper closed againist. Fell the top lip for nicks, gouges or bumps . If its really bad just replace the whole flush valve, they come with a new, matching flapper

The last time I had this issue with a similar toilet I replaced the overflow tube but could never get the tank to seat without leaking and ended up cracking the tank, ending with a new toilet. I'd rather fix this one without the same thing happening again. What could have gone wrong on the one that I broke, it kept leaking between the tank and toilet.

Has toilet been coming on intermittently during this time?

Yes, apparently water in the tank is leaking through the overflow pipe, thus the float device detects the low water in the tank and then runs to bring the water level back up. This goes on all day/night.

Then you adjust the float... because the water should be lower than the top of that tube.

The water level is below the level of the top of the overflow tube, but water level continues to drop in the tank thus the off and on running of the water to bring up the level in the tank.

Fixed it, this did the trick http://www.homedepot.com/catalog/productImages/145/b6/b641c38f-37fc-4782-967c-cbb0edce1aa2_145.jpg

Took 15 minutes. Nothing to take apart, whew, some relief felt on this one.

Thanks folks

So the seat wasn't smooth and clean after all... as that is a kit to repair a damaged seat

I wiped it out and ran a finger around it (the seat) felt smooth, don't know, but the kit fixed it up just fine. No more running.

I wiped it out and ran a finger around it (the seat) felt smooth, dunno, but the kit fixed it up just fine. No more running.

That's what really matters most anyway.