Toto toilet tank leak

Discussion in 'Toilet Forum discussions' started by wolcott, Mar 23, 2006.

  1. wolcott

    wolcott New Member

    Mar 23, 2006
    I recently installed at Toto Drake Toilet, model CST744SL. The toilet flushes beautifully, but there is a chronic leak on the floor that comes from either the back of the toilet, where the tank joins the toilet, or from the tank mounting bolts. This leak occurs without the toilet being flushed, so it was obviously not a leaking wax ring or leak around the bowl to tank gasket. I tried working with the tank mounting bolts, this did not correct it. So, I removed the tank from the bowl, used the tank mounting bolts to plug the tank mounting holes, propped up the tank, and poured in a gallon of water to trace the leak. I noticed the fill valve did not leak, and the tank mounting bolts were leak free, but there were two leaks in the flapper valve area. One was a drip coming past the flapper valve, but I wasn’t concerned about this at the time; it might waste a little water, but would not end up on the floor. The other leak, which worried me more, was a slight leak between the nut that attaches the flapper valve body to the tank and the threads protruding under the tank from the flapper valve body. While it looks like this leak would drain past the tank to bowl gasket into the toilet bowl, I could see where once the tank was tightened down well, it could seal the bowl to tank well enough so the leak could leak out from the top of the tank to bowl gasket to the top of the bowl, and from there to the floor. Now, my questions are:

    1. Does it look like this flapper valve nut leak could be the cause of the water on the floor, or could it be something else?

    2. If the cause of the leak appears to be the leak past flapper valve body , what is the best way to seal this? Just take it apart and apply RTV or some other sealant, or is there a better way?
  2. Terry

    Terry Administrator Staff Member

    Aug 17, 2004
    Bothell, Washington
    Sanding where the tank bolts go through.

    If it's leaking past the flush valve, remove it and sand the inside of the tank.

    Then reasemble the parts.
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  4. wolcott

    wolcott New Member

    Mar 23, 2006
    Many Thanks. I tried sanding the flapper valve gasket contact area in the bottom of the tank well, and then blocked up the tank, plugged the mounting holes, and filled it with water to test it. It looks like this cured the problem of the leak around the flapper valve body, so I reinstalled the tank. In a day or so I'll know for sure if I fixed the problem.
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