Repairing a Moen Pressure-Balanced Shower Valve

As with any faucet brand, a Moen shower valve contains working parts that can go bad over time. Moen pressure-balance shower valves are designed so they sense hot and cold water pressure and keep them in balance, preventing the shower from sudden surges of hot or cold water. When the shower valve begins leaking or fails to correctly balance the hot and cold water, fixing the problem is usually a simple matter of replacing the insert cartridge.

Tools and Materials You Will Need

• Rags
• Allen wrench
• Screwdrivers
• Needlenose pliers
• Flashlight
• Silicone grease
• New shower cartridge
• Moen cartridge puller (optional)

1. First, shut off the water to the shower faucet at the fixture shutoff valve. Drain any water remaining in the pipes by turning on the faucet. If the shower does not have a fixture shutoff valve, then shut off the water to the entire house at the main shutoff valve, and drain the pipes by opening the lowest faucet in the home. 
2. Block the shower drain with a stopper or rag to prevents screws and other parts from falling down the drain.
3. Use an Allen wrench to remove the set-screw at the bottom of the handle.
4. Pull the handle straight outward to remove it.
5. Set aside the handle and set-screw

After removing the handle, you can access the handle adapter and temperature control component on the valve:

1. Unscrew the black plastic handle adapter with a Philips screwdriver and pull it straight out.
2. Next, pull the two white plastic pieces that make up the temperature limit stop kit straight out.
3. Grip the chrome sleeve and pull it straight out. This will expose the retaining clip that holds the cartridge in place.
4. Set the handle adapter and chrome sleeve aside; they will be used again when the new cartridge is installed.

Before the cartridge can be removed, you'll need to remove the cartridge retaining clip. Note the location of the clip before removal, as it will need to be re-installed the same way after the new cartridge is inserted.

To remove the retaining clip, use a pair of needle-nose pliers or a flat screwdriver. Grip the top of the clip and pull it straight out.

Set the retaining clip aside; you will use it with the new cartridge.

With the clip removed you can now pull the cartridge out. A Moen cartridge puller (shown here) makes removing the cartridge a little easier, but it is not required.

If you don’t have a cartridge puller, use the plastic adapter that comes with the new cartridge to remove the old cartridge. Attach the plastic piece to the end of the cartridge, and turn it from side to side with pliers as you pull. When the cartridge is partially out, grasp the brass stem with pliers and pull the cartridge fully out.

Before installing the new cartridge, look inside the valve with a flashlight to make sure it's clean.

1. Remove any debris that may obstruct the installation of the new cartridge.
2. Lubricate the rubber parts of the new cartridge with silicone grease.
3. Push the cartridge in place, making sure the H/C marking on the face of the cartridge is on top, so the hot is on the left and cold is on the right.

With cartridge inserted, you'll now install the retaining clip and the chrome sleeve:

1. When the cartridge is in place, reinstall the cartridge retaining clip. If you have trouble getting the clip into position, try moving the cartridge just a bit by using the plastic cartridge puller or a Moen cartridge puller. Note: Do not try to force the clip into position; it should slide in easily.
2. With the retaining clip in place, slide the chrome sleeve back into position over the cartridge.

The set of two white plastic pieces called the temperature limit stop kit, provide a scald guard feature on some Moen shower valves. If you have very hot water and are concerned that children using the shower may be scalded, the scald guard is a great feature. It allows the valve to be set up so that no matter how far the handle is turned toward the hot side, it will not go past a certain point.

Setting up the scald guard is easy, but you may have to try it a few times before you get the temperature where you want it. The water supply can be on while you set up the scald guard, but the handle and handle adapter have to be off.

To turn the water temperature down, move the outermost white piece to the right to limit the hot. The number of splines you move will depend on how much restriction you want. Try turning the valve on with the handle adapter loosely in place until you find the temperature you want.

To turn the water temperature up, move the outermost plastic piece to the left a few splines.

Note: Be careful when testing. Turn the hot water on slowly so you can stop before it gets hot enough to scald you.

Reassemble the handle by reversing the order used to disassemble it: 

1. First, install the black handle adapter and tighten it with a screwdriver. Make sure the black handle adapter is screwed on tightly before proceeding.
2. Put the handle on the cartridge stem, insert the set-screw, and tighten it with an Allen wrench.
3. Turn the water on and test it to make sure the valve gets cold first, then warmer as you rotate the handle.