Remove the Right Kohler Assembly Without Damaging the Valve

For a confirmed Kohler K-304 valve, cartridge removal means shutting off the water, relieving pressure, removing two retaining screws and the collar if present, lifting off the mixer cap, then pulling out the separate pressure-balancing unit (PBU). The K-8304 uses a one-piece cartridge, so this sequence does not apply to it. Kohler documents the K-304 sequence in its service instructions.

Select your confirmed valve and water-shutoff status to see whether these removal steps apply.

Confirm the Valve Behind the Trim

Match the exposed valve—not just the Kohler logo or handle style. Before loosening anything that retains water pressure, photograph the valve face and record any model or part markings. Compare the screw layout, stem shape and assembly with the manufacturer’s diagram.

Valve or Assembly	Identification and Parts Distinction
K-304 with separate mixer cap and PBU	The front cap and rear PBU are separate components. Kohler’s 2018 brochure lists GP876851 as a combined kit containing GP77759 and GP800820.
K-8304 Rite-Temp	Uses a one-piece pressure-balancing cartridge. The same brochure lists GP800881 for this valve.
Early pressure-balancing valve with brass cap and three-ribbed stem	Kohler says a new PBU requires the GP876851 mixer-and-PBU combination. Do not assume a PBU-only replacement will work.

These distinctions come from Kohler’s 2018 service-parts brochure, showering section and PBU installation guidance. They are identification leads, not a substitute for checking your exact valve’s parts diagram before ordering.

Stop if the assembly does not match. A thermostatic control, transfer valve or multi-handle shower needs its own service instructions. If you are unsure which control you are working on, first distinguish the transfer valve from the mixing valve.

Remove the K-304 Mixer Cap and PBU

Have a correctly fitting screwdriver, the tools specified for your trim, pliers, towels and a small parts tray ready. Cover the drain so the retaining screws cannot disappear.

1. Shut Off Both Supplies and Relieve Pressure

Isolate both hot and cold supplies using verified shutoffs, or shut off the main supply. Turn the shower handle to ON to relieve pressure. Confirm that sustained flow stops before proceeding; the shower handle alone is not a supply shutoff.

Kohler specifies water shutoff and pressure relief in its K-304 cleaning procedure. If water keeps flowing, stop and resolve the shutoff problem before removing the retaining screws.

2. Remove the Handle and Trim

Follow the instructions for your particular trim model. Kohler handles do not all use the same hidden screw or threaded attachment. Lay out adapters, sleeves and screws in removal order, and photograph the exposed cap before disturbing it.

If the handle will not release after its documented fastener is loosened, stop rather than forcing the stem.

3. Remove the Two Retaining Screws and Collar

On the confirmed K-304 assembly, remove the two screws securing the cap. Remove the collar if present—Kohler notes that some assemblies do not have one. Keep it separate from the decorative trim hardware so its position is clear during reassembly.

4. Lift Off the Mixer Cap, Then Withdraw the PBU

Remove the mixer-cap assembly. The PBU remains behind it in the brass valve body. Kohler’s service instructions specify using pliers to remove the PBU. Pull it outward without levering a tool against the brass sealing surfaces.

Stop if a screw strips, plastic breaks, or the valve body moves with your pulling force. Do not escalate to drilling, heat or prying against the valve body. Leave the supply isolated and arrange professional removal rather than risk damaging the in-wall plumbing.

Match the Removed Parts Before Ordering

Photograph the cap and PBU from the front, side and back. Record markings, overall dimensions, stem profile, mounting-hole layout, locating notch and seal positions. Keep the old parts until the replacement is installed and tested.

For a K-8304, use that valve’s service diagram rather than searching for a separate K-304 PBU. Its one-piece cartridge requires a different procedure; neither the removal steps above nor the reassembly steps below apply to it.

Seat the K-304 Seals and Collar Correctly

Inspect the brass body for debris and protect its sealing surfaces. Check that the small O-rings on the back of the PBU and the cap’s seals are present and correctly seated.

Follow the replacement kit’s seal and lubricant instructions. Kohler’s K-304 procedure calls for silicone lubricant on the small PBU O-rings to hold them in place and on the large O-ring around the cap.

Align the body’s locating tab with the PBU notch, then seat the PBU straight. Do not insert it at an angle and rotate it into place: Kohler warns that this can displace the small O-rings and cause leakage.

Press the mixer cap into place with its black top at the 12 o’clock position. Fit the retaining collar over the cap—not between the cap and PBU—and secure the two screws. Collar designs vary; use the illustrations and collar-selection guidance in the K-304 service-kit instructions.

Check for Leaks and Reset the Temperature Limit

Once the assembly is fully seated and secured, restore water and check operation and leaks before covering it with trim. If water will not shut off, isolate the supply again before checking the seals and collar placement.

Kohler identifies displaced O-rings and a collar incorrectly placed between the cap and PBU as causes of continuous flow after repair.

Finally, reset the temperature limit using the procedure for your valve and measure the outlet temperature with a thermometer. Kohler’s K-304 adjustment guidance says not to set it above 120°F. Do not assume the old limit setting remains correct after replacing the cap.