toilet leak

This one is driving me nuts
Toilet with a new flush valve is leaking down. tank leaks down about two inches in about ten minutes and opens the fill valve. thinking it is a bad flapper, I replaced with a new one. no change.
Thing is, if I turn off the water so that the fill valve does not open the thing leaks down about three inches and then stops. No more leaking. I checked the fill pipe just above the stopping point and there are no holes in it.
Is it possible to have an internal leak in the wall of the porcelin tank that leaks internally to the connection between the tank and the lower unit? that seems unlikely but I can't think of any other possiblity It is definitely not leaking anywhere externally
Or is that slight reduction in head pressure enough to stop the leak. That doesn't seem likely. There is still six inches of water in the tank when it stops.
Thoughts?
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Your missing something
Vaseline on the flapper, then operate a couple of times. Look for the seal ALL the way around.
I guess it is possible that the porcelain is leaking. More likely the gasket between the tank and bowl.
Have you checked the stand pipe for cracks? The tube that rises up and is the upper over flow limit. Pretty cheap to replace.
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But it stops leaking with six inches of water left in the tank?

If so, why does it stop with six inches of water still in the tank?

Yes, as mentioned above it stops with six inches of water left. I checked the standpipe in particular just above the point at which the water stops to see if there is a hole or leak. No. and when it is leaking there is no water running into the standpipe. I checked it with a flashlight.
I understand the principle and the propensity for leaking at the gasket, flapper, and even the standpipe connection to the flush valve body. What I can't figure out is why does it drop three inches and then stop leaving six inches of water still in the tank? The only thing in that three inch distances is a portion of the standpipe. And the tank itself.

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replacement parts cost less than aggravation, buy a full set and return unused parts is a possible shotgun repair solution. excellent online free troubleshooting at: www.fluidmaster.com
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On Mon, 16 Jan 2006 15:51:28 -0600, Frank Boettcher

Push down three inches on everything that floats, and see if the leak stops.
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Goedjn wrote:

    Had one that did the same thing. During refill, water goes through the small plastic tubing into the center of the overflow pipe to assure refill the trap. If the plastic tubing is pushed down below the level of water in the tank, it'll siphon the water out to that level and then stop at that level. The answer on mine was to cut a few inches off the plastic tubing so the end was above the normal water level.
Bob
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