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Thread: Toilet leaks from bottom after installing new tank kit.

  1. #1
    DIY Junior Member midlodj's Avatar
    Join Date
    Sep 2013

    Default Toilet leaks from bottom after installing new tank kit.

    I've just installed a Korky Quietfill Complete Kit (4010) in a Kohler K-4620-DA 2-piece toilet. There is now leakage from under the toilet. when I flush. I thought I'd traced the leakage back to the tank bolts, but have them as tight as I dare. I'm left wondering (as I'm certainly no professional) if water is getting past the seal between tank and bowl. The original Kohler kit had a much more substantial seal....a one-piece rubber gasket that served to seal all three tank bolts and the tank/bowl. Wondering if I need to buy all Kohler replacement parts, or ditch the toilet. Reason for replacing was hearing water "running" all the time from that bathroom/toilet. After initial install of Korky kit...no more running water sound, but definately the leak problem. I'm also wondering if I've incorrectly installed either the refill valve assembly, or the flush valve assembly, or both.

  2. #2
    Retired Defense Industry Engineer jadnashua's Avatar
    Join Date
    Sep 2004
    New England


    The bolts that hold the tank on must only have a rubber washer IN the tank. The metal washer must go outside the tank. If you have a metal washer in the tank, that may be causing the leak. Also, it is best if you actually use four nuts and metal washers. The first one directly on the bottom of the tank to seal it up well, then, the second one to attach it to the bowl. Most toilets have enough room for that second nut and washer, but knowing Kohler, maybe not!

    Generally, you can tighten the tank bolts up until the tank is sitting on it's spacing legs (but, your Kohler may not have any!) IF you tighten them slowly, and a little bit, alternating side to side.

    Your toilet may have been specifically designed for that big gasket, and may not work well with a generic rebuild kit. Can't say without seeing it - Kohler has a tendency to do things their own way, and generic is distasteful to them.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  3. #3
    DIY Senior Member wjcandee's Avatar
    Join Date
    Apr 2012
    New York, NY


    I have installed this kit on a number of toilets. It should work fine on your Kohler.

    The gasket under the toilet tank that has the three holes is there to in part support the tank. It's not so much about sealing as supporting. If you haven't tossed it, you might think about integrating it into your setup if you can to make the tank more stable, if you can't get it there yourself.

    And preventing leaks with this kit isn't so much about tightening the tank to the bowl as it is other things.

    First, make sure as Jim said that the hardware in the tank has a bolt head over the rubber washer, and that the metal washer is outside the tank. On this kit, they just give you one washer and one rubber washer, so you put the metal washer and the nut under the hole in the base. If you can actually see water dripping out of the bolt holes, then you may wish to replace the Korky hardware with something like this, that has two of everything per bolt: http://www.amazon.com/Lasco-04-3673-...ilet+tank+bolt

    What you do is put the rubber washer under the bolt head inside the tank, and make a solid seal by putting the metal washer and nut on the other side of the tank. That way, whatever tension is applied to the assembly from whatever direction when you mount the thing to the base, there is already a solid seal inside the tank. Then you use the second rubber washer, second metal washer, and second nut to secure the tank to the base. This is how pros do it and some manufacturers set it up.

    You might also sand a little with very fine paper (before you insert the washer and bolts) around the bolt holes in case there is a little rough area that is interfering with the seal.

    If you're not sure that that's where the leak is, check the way you have installed the Korky flush valve. The gasket on the outside (the big rubber thing) does NOT seal the flush valve to the tank. That is the function of the red rubber thing on the bottom of the flush valve on the INSIDE of the tank. There's a chipboard washer that goes between the tank and the big plastic nut on the outside of the tank to make it easier to turn. You should hand-tighten that big plastic nut and then apply about a half-turn with channel locks. If you do that, you won't have a leak at that point (again think about sanding any rough edges around the hole in the tank). The big doughnut washer there just compresses to provide stability and prevent leaks from water splashing back up and out of the hole in the base into which the fill valve empties. It doesn't require much compression to make a seal against that, but if you have a leak between the flush valve and the inside of the tank, it can come out over the top of that doughnut.

    If you have installed the Korky kit properly, the tank should be very stable. You can tighten as long as no porcelain is contacting porcelain. You can check this by sliding a piece of paper around under the tank and by examining the tank and base to see where the points of contact are.

    The original Kohler parts are not necessary and shouldn't add anything.

    You can also call Korky for help at 1-800-LAVELLE. They are nice folks in Wisconsin and happy to help you.

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