I have a plumbing problem in the form of a leaky toilet tank. The leak appears to be coming from somewhere between the tank and the bowl, where the tank meets the bowl.

At first I thought it might be the toilet tank bolts so I replaced them and made sure that the nut on the under side of the tank was fairly tight while not making it too tight so as to crack the tank. I then replace the tank and found that replacing the tank bolts didn't help at all.

Second, I thought the source of the leak may be the tank gasket so I replaced that and still no help – the leak still exists.

Third, I decided to remove the tank and put it on a set of blocks and placed it on a table so I could see what was happening and maybe determine exactly where the leak was coming from. I checked the tank bolts again and they still seemed to be secure , but just to be safe I tightened them up a little. With the flapper closed I filled the tank about ¼ full and had no leakes. I then re-mounted the tank to the bowl such that the tank felt tight and was resting securely on the front and back ridges of the Bowl. I then re-filled the tank manually until the tank was about ¼ full. There were no leaks at this. I then connected the water source to the tank and filled it about ¾ full. I let it set for 10-15 minutes and when I checked it the water was leaking fairly heavily again from somewhere between the tank and the bowl. It seems as though the leak only happens when the bowl is full or nearly full of water.

I am at a loss as to what the problem is. Can someone help me with this issue ?

Hi Dhenry

Any chance there is a hairline crack in the tank near the bolts or the fill valve? To check this you would fill the tank about 1/4 of the way with water and then add a food coloring to the water until it is a dark color and then let that sit for awhile and then use a flashlight to inspect the tank for colored cracks, right?

If the tank isn't cracked then there is a good chance that the entire FLUSH VALVE ASSEMBLY may need to be replaced, but before we go there tell me just how much you are tightening the tank to bowl bolts... should be pretty snug in that the bowl should just wiggle a 1/4" back and forth and no more...

Also, you said you tightened the nut... was that the large nut associated with the flush valve? If so, was this nut loose... how loose?

Post back and let me know more...

Mark

Yes, it appears that there are some hairline cracks around the float valve and at least one of the tank bolts.I am not tightening the tank bolts all the way for fear of cracking tank. I did not tighten the large flush valve plastic nut.

In my opinion, you need to tighten the tank down in such a way that any large (or extra large) relative can pop over any time and use the toilet, right? If not, one day someone will show up and lean against that toilet tank and the toilet will probably start leaking... and probably during the super bowl or something like that, huh?

I'd tighten this all up well (leave 1/4" wiggle/play in tank). If the tank cracks at least it cracks now while you have time to replace it with a new one... ;)

If that fails to resolve the issue then you'll probably need to replace the entire flush valve assembly to put this to rest, OK?

Good luck!

Mark

As I mentioned in my 1st reply, I tightened the tank down to the bowl just about as fare as they would go. What about the hairline cracks? Should I replace the tank ?

Dhenry, as Mark suggested, you will need to replace the tank. Good luck