Toto CST744S with a leaky valve - help!

Discussion in 'Toilet Forum discussions' started by Ramesh Moorthy, Jun 14, 2014.

  1. Ramesh Moorthy

    Ramesh Moorthy New Member

    Messages:
    3
    Location:
    Maryland
    Hi - tried searching for the problem that we are having, and want to make sure I replace the valve/system only if I need to.

    it appears to have a G Max valve (picture below)

    toto toilet valve.jpg

    The water keeps filling, and overflows the white tube.

    If I lower the level of the water with the screw, it works the first fill, and then overflows the tube (and keeps running) the 2nd fill.

    Am I doing something wrong in adjusting the height or is there another adjustment or repair that would work?

    Thanks so much.
    Last edited: Jun 14, 2014
  2. Terry

    Terry Administrator Staff Member

    Messages:
    14,798
    Location:
    Bothell, Washington
    Last edited: Jun 14, 2014
  3. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,820
    Location:
    New England
    The version of the fill valve you have should not need to be adjusted up/down once initially installed. There's only one serviceable part...an inlet filter. You could try cleaning that, but you'll probably be better off with the Korky valve. Those have an easily replaceable seal that costs in the order of $3 and takes maybe a minute to replace without tools, should it ever fail to fully stop the water from flowing.
  4. wjcandee

    wjcandee Wise One

    Messages:
    1,771
    Location:
    New York, NY
    Yes you need to change the valve. Use this one, the one Terry recommends above, the one with the silver cap: http://www.lowes.com/pd_336988-868-528MPK_0__?Ntt=528mpk&UserSearch=528mpk&productId=3284948&rpp=32

    It's an easy diy job and there are korky videos on the Internet to help. 15 mins max to swap it. www.korky.com



    I replaced the fill valves on all the toilets in our house with the Korky 528, including on a CST744S; it's easy and I haven't had to touch them since.

    Let us know how it goes and if you need any more help.

    BTW, the Korky video's announcer ("Jules") is correct about how to adjust the refill, but the graphics are backwards. If the water ends up higher than the mark (too high), turn the knob counterclockwise slightly. If it is lower than the mark (too low), turn it clockwise. What she says is right, what the graphics say is backwards. I emailed Korky about this and they say they are going to fix it.
    Last edited by a moderator: Jul 19, 2014
  5. Ramesh Moorthy

    Ramesh Moorthy New Member

    Messages:
    3
    Location:
    Maryland
    Thanks!

    Thanks so much Terry, jadnashua, and wjcandee! Very much appreciate the advice.

    Two more questions -

    1. Several other threads recommend the 528T for the Totos vs. the 528MPK... I was in Lowe's and didn't buy it (I hadn't seen your posts yet, which is a bummer :<), but could go back and buy it tomorrow. In the meanwhile I ordered the 528T online :< (which I can still cancel, I think). Is there any reason, now that I have the 528T on order, to go ahead and use it, or is the MPK just as good?

    2. The Fill Valve in question is only a few years old - shoudl they fail that fast, and if not, does that possibly mean I have some kind of water issue causing it? We do not use any chemicals in the tank, but it is pretty dirty in there.

    Appreciate the advice on these last two questions...

    Thanks so much!!!!
  6. Terry

    Terry Administrator Staff Member

    Messages:
    14,798
    Location:
    Bothell, Washington
    The 528T works great for those. We've installed plenty of those too. It's a branded model, and the MP isn't. Both work.
  7. wjcandee

    wjcandee Wise One

    Messages:
    1,771
    Location:
    New York, NY
    The 528Tgives you the right refill percentage for gmax, which you have. It's fixed in place whereas the mp is variable, and cheaper.
  8. Ramesh Moorthy

    Ramesh Moorthy New Member

    Messages:
    3
    Location:
    Maryland
    Thanks so much everyone! Replaced the fill valve with a 528T in a matter of 10 minutes and it has worked perfectly since. Really appreciate the help!
  9. wjcandee

    wjcandee Wise One

    Messages:
    1,771
    Location:
    New York, NY
    Thanks for reporting back! I was wondering how you made out! Congratulations on a job well done.
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