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

[tbr220]

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?

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.

[jadnashua]

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.).

[hj]

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.