Kohler’s single handle Rite-Temp shower valve (K-304, K-8304, K-11748 bodies) has two serviceable parts: the mixer cap at the front, and the pressure balancing unit behind it. A drip from the showerhead or tub spout after shutoff means the seals in one or both are gone, and Kohler’s answer is to replace both together.
Before you start. Shut off the water at the house main (shower valves rarely have their own shutoff), then open the valve to confirm the water has stopped. You will need a screwdriver, an adjustable wrench or pliers, and for most handles a hex key (an Allen wrench, sold as an inexpensive set at any hardware store). If a shutoff valve will not turn or starts to drip, or anything is corroded and will not loosen with moderate force, stop and see when to call a plumber. New to this? Start here explains the parts and tools in plain language.
Not sure this is your faucet? See how to identify your Kohler cartridge without a model number, or how to find your brand and model.
| Part | What it is |
|---|---|
| GP77759 | Mixer cap assembly with collar, screws, O-rings, lubricant, and the temperature limit stop. Fits the K-304. |
| GP800820 | Current pressure balancing unit. Replaces the discontinued GP500520. |
| GP76851 | Kit with both the GP800820 unit and the GP77759 cap. The simplest buy. |
| 1307346 | Retro mixer cap kit for fitting newer trim to an older K-304. |
| K-8305 | Complete one-piece cartridge for K-8300 series bodies. Reversible for crossed supplies. |
GP77759 at Kohler.com. GP76851 at Kohler.com. GP77759 at Home Depot.
Symptoms Kohler ties to the Rite-Temp
- Drip from showerhead or spout after shutoff: cap and balancing unit seals. Replace both.
- Temperature swings while showering: hot and cold supply pressures differ by more than about 5 psi. The balancing unit cannot compensate beyond that; a pressure regulator on the supply is the fix.
- No water at all: the balancing unit needs at least 45 psi on both sides. Check both stops are fully open.
- Hot comes on first and cools as you turn: supplies are reversed. Rotate the mixer cap 180 degrees.
- Small springs or rubber boots fall out when you open it: pre-2005 cap. Replace the cap; the boots are not sold separately.
Steps
Kohler publishes this procedure as a video on its support site. The written steps below follow it.
- Shut off the water. Many Rite-Temp bodies have integral screwdriver stops; otherwise use the house main. Open the handle to relieve pressure.
- Remove the handle set screw and the handle, then the trim plate screws and plate.
- Remove the two Phillips screws on the face of the valve and pull the mixer cap assembly straight forward.
- Grip the balancing unit with pliers and pull it straight out.
- Clean the brass bore with vinegar and a cloth. Do not use anything abrasive.
- Grease the new unit’s O-rings with the silicone supplied. Align the tab on the unit with the notch in the body and press it in square.
- Fit the new cap. The metal collar goes in front of the mixer cap, not between the cap and the balancing unit; in the wrong place it will not seal.
- Refit the two face screws, then the trim.
Setting the maximum temperature
With the trim off, remove the black O-ring, the caution tag, and the red (on older valves, black) collar from the brass stem. Turn the stem clockwise to run water and check the temperature with a thermometer. When it reaches the hottest you want, refit the collar in that position. Kohler’s limit is 120 F. On the GP77759 cap the limit screw takes a 5/64 inch hex key.
Kohler pageIdentify your cartridgeStart hereWhen to call a plumber
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