Kohler k-401 Mixing valve, Cartridge Repair or Replace?

Discussion in 'Shower & bathtub Forum & Blog' started by mrspaceman, Oct 3, 2010.

  1. mrspaceman

    mrspaceman New Member

    Messages:
    11
    Location:
    New York
    I have a shower with a K-401 Mixing valve. Shower used to be hot enough, but now it runs luke warm though the temperature control is max'd out (i have the mixing valve turned all the way hot without the limit stop installed). Hot inlet water temperature is about 130.

    It doesn't look like there is any way to adjust the mixing ratio.

    Any suggestions?

    Thanks!

    http://www.designtool.kohler.com/us/detail.jsp?item=274302

    Attached Files:

    Last edited by a moderator: Nov 18, 2012
  2. Redwood

    Redwood Master Plumber

    Messages:
    7,452
    Location:
    Connecticut
    Is this hot water inlet temp 130 when the shower is flowing? Or does it drop off...

    If it is then you are probably looking at a #78913 thermostatic cartridge...
    I hope you are the original owner and have a warranty... Otherwise you are looking at $234.90...
    Call 1-800-4KOHLER for parts...

    Attached Files:

    Last edited by a moderator: Nov 18, 2012
  3. mrspaceman

    mrspaceman New Member

    Messages:
    11
    Location:
    New York
    Hard to tell. I measured the inlet temp by turning on the hot water at the bathroom sink. It reads 130 steady.
  4. mrspaceman

    mrspaceman New Member

    Messages:
    11
    Location:
    New York
    PS - I am the original owner - - whew. Kohler has been great responding to warranty issues. Of course, the fact that this is the second Kohler item (other was a kitchen faucet) that failed is not a good thing. Items were both 7 years old.
  5. Redwood

    Redwood Master Plumber

    Messages:
    7,452
    Location:
    Connecticut
    I would say crank up the shower to where it is malfunctioning then while it is flowing check the temperature at the lav faucet.
    Just to make sure it isn't a water heating problem.

    Getting free parts is a good thing!
  6. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,508
    Location:
    Cave Creek, Arizona
    A sticking balancing spool could also limit the amount of hot water flowing from the faucet.
  7. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    hj....you're slipping! It is a thermostatic model,,,no balance spool.
  8. jsmabrey

    jsmabrey New Member

    Messages:
    3
    Location:
    Taos, NM - US
    Kohler 401 Mixing Valve Cartridge Repair or Replace?

    Can the Kohler Cartridge #78913 be repaired by a DIYer? The valve stem has only 1/4 rotation with the limit stop removed. Therefore the shower produces only hot and hotter flow. The supply of both hot and cold is within specs. The inlet check/stop valves are open.

    A new cartridge is about $200 which I would like to avoid with a in-house repair. Any advise?
  9. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,508
    Location:
    Cave Creek, Arizona
    Cartridges can seldom be "repaired". The normal operation is for the valve to START with cold water and then go to warm and finally hot. IF yours does NOT do that, then something is "stuck" preventing the flow of cold water.
  10. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
  11. jsmabrey

    jsmabrey New Member

    Messages:
    3
    Location:
    Taos, NM - US
    Can you address the 1/4 rotation? Does the limited rotation confirm that the cartridge is probably defective? What inside the cartridge could go bad or be obstructed that could not be cleaned? Could I get it back together?
  12. jsmabrey

    jsmabrey New Member

    Messages:
    3
    Location:
    Taos, NM - US
  13. marcusk

    marcusk New Member

    Messages:
    1
    Location:
    San Jose, CA
    Hi jsmabrey,

    I'm having the same problem with my k-401 well the opposite.. I have cold and slightly warm.

    How did you get the cartridge out? Did you use an 11/16 wrench on the stem? Or do you have some kind of larger 1in diameter tool to remove it by the notches on that wider part? Also is it standard thread or reverse?

    The reason I ask is I have cranked on the 11/16 stem quite hard and I can't get it to budge, I don't want to break anything.
    Last edited: Nov 25, 2011
  14. mrspaceman

    mrspaceman New Member

    Messages:
    11
    Location:
    New York
    Kohler K-401 Mixing Valve

    So here I am exactly two years later with the same problem. I have a Kohler K-401 mixing valve in my shower. Two years ago, the water started running cool to warm, even though the valve was turned to as hot a temperature as possible. I ended up replacing the Kohler Cartridge #78913.

    Two years later, I am having the same problem. I pulled the cartridge, inspected it. It looked like one of the screens moved over the bottom o-ring. I moved the screen back. Replaced the cartridge and now the water is cooler.

    Seems odd to have the same problem again. As Kohler has a life-time warranty, I can replace the cartridge, but maybe there is something else causing the problem? Other than the cartridge there isn't much else in the system. Thoughts?

    Also the cartridge has a very large diameter with a very fine thread. I live in fear of cross threading. If there are tips (other than patience) I'd appreciate it.
  15. tbr220

    tbr220 New Member

    Messages:
    2
    Location:
    St Augustine, FL
    I have two of the same mixers, both failed to adjust from full hot. Rather than pay for two new valves I have taken each one out and soaked them in CLR for an hour, rinsed and re installed, both work fine. I have had to do this twice a year for the four years I have lived here to clean out the calcium buildup even though I have a water softener. I remove the screens and o rings first then soak the metal parts in a glass mug then rinse and lube the o rings with silicone grease, re adjust the temp limits and we are back to happy until they get stuck again. Hope this helps.
  16. tbr220

    tbr220 New Member

    Messages:
    2
    Location:
    St Augustine, FL
    I have two of the same mixers, both failed to adjust from full hot. Rather than pay for two new valves I have taken each one out and soaked them in CLR for an hour, rinsed and re installed, both work fine. I have had to do this twice a year for the four years I have lived here to clean out the calcium buildup even though I have a water softener. I remove the screens and o rings first then soak the metal parts in a glass mug then rinse and lube the o rings with silicone grease, re adjust the temp limits and we are back to happy until they get stuck again. Hope this helps.
  17. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,917
    Location:
    New England
    Sounds like a crappy design - you should get much longer than 6-months satisfactory use out of it between your maintenance, regardless of your water quality unless it is full of hard debris (sand, dirt, etc.).
  18. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,508
    Location:
    Cave Creek, Arizona
    quote; It is a thermostatic model,,,no balance spool.

    The specifications say it has "antiscald protection" and "crossover protection" so there is something inside it besides the cartridge. But clogged screens might affect the flow to the point that the thermostat would not work properly, but more than likely it is just worn out.
  19. dbjacobson

    dbjacobson New Member

    Messages:
    1
    Location:
    FLORIDA
    so basically, to remove the cartridge I use a wrench of sorts to remove the cartridge from the photo in Post #1. Could anyone give me any hints on what size/kind of wrench to use?
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