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

petercat said:

This excellent YouTube video, posted in 2020, will answer a lot of questions, including a two-wrench trick for removing the cartridge.

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petercat said:

I added a comment to this video that describes the wax motor at the heart of the Kohler thermostatic valve. Here is an excerpt:

There is car thermostat shown at 7:00 in the video. The springs do not respond to temperature. Rather, the thermostat contains a "wax motor" (https://www.coolcatcorp.com/thermostats/Wax Thermostats.html). The wax is incompressible, but expands when it melts, pushing a pin.

I learned about wax motors when I spent a brief stint as an appliance repairman. A wax motor is used inside a dishwasher to operate a soap dish door when an internal heater is activated to melt the wax (

). A wax motor is low cost, generates in irresistable force, is very reliable, and should operate hundreds of thousands of cycles.

In the Kohler video, from 4:55 to 5:10, the wax motor in the thermostatic valve is shown. The wax expands when it melts, pushing the pin and compressing the spring.

Here is an excerpt from the description of a Crosswater thermostatic valve that looks to be identical to the Kohler (https://www.fruugo.us/thermostatic-...rosswater-gr-05t-sol-assy/p-10229921-21509092)

"A wax capsule can be found inside the Crosswater GP0012174 / RV1102RC. The capsule is responsible for water temperature regulation by counterbalancing the flow of hot and cold water to generate a preferable temperature."

Why does the Kohler cartridge fail? I'm not sure. Does the wax motor pin get stuck due to deposits or metal corrosion?

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