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.
Equipment / Tools
- Allen wrench
- Phillips screwdriver
- Moen cartridge puller (optional)
- Needle-nose pliers
- New shower cartridge
- Silicone grease
Shut Off the Water
First, shut off the water to the shower faucet at the fixture shutoff valve. If there are no fixture shutoff valves, you will need to turn off the water supply to the house at the main shutoff valve. Drain any water remaining in the pipes by turning on the faucet. If you had to turn off the water at the main house shutoff, then open the lowest faucet in the home to drain the pipes.
Remove the Faucet Handle
Block the shower drain with a stopper or rag to prevent screws and other parts from falling down the drain. Use an Allen wrench to remove the setscrew at the bottom of the handle. Pull the handle straight outward to remove it. Set aside the handle and setscrew.
Remove the Handle Assembly and Sleeve
Unscrew the black plastic handle adapter with a Phillips screwdriver and pull it straight out. Pull the two white plastic pieces (the temperature-limit stop kit; not all Moen faucets have these) straight out, keeping the two pieces together so you don't loose the temperature setting. Grip the chrome sleeve and pull it straight out. This will expose the retaining clip that holds the cartridge in place.
Remove the Cartridge Retaining Clip
Note the location of the cartridge retaining clip; you much reinstall it the same way after the new cartridge is in place. Use needle-nose pliers to grip the top of the clip and pull it straight up to remove it. Set the retaining clip aside; you will use it with the new cartridge
Remove the Cartridge
A Moen cartridge puller (shown here) makes removing the cartridge a little easier, but it is not required. To use the tool, fit it onto the end of the cartridge and thread the puller screw into the end of the valve stem (the same part that accepts the valve handle). Make sure that it goes in straight and is not cross-threaded. Pull the tool while rotating back and forth (clockwise and counterclockwise) to extract the cartridge. Loosen the puller screw to remove the tool from the cartridge.
If you don’t have a cartridge puller, use the plastic adapter that comes with the new cartridge to remove the old cartridge. Fit the plastic piece onto the cartridge stem. Grip the adapter with pliers and rotate it back and forth as you pull out the cartridge. When the cartridge comes out partway, grip the cartridge stem with pliers and pull the cartridge fully out.
Moen cartridge pullers come in different sizes for different cartridge models. Some cartridges require the use of the nut on the tool, while others do not.
Install the New Cartridge
Look inside the valve body with a flashlight to make sure it's clean. Remove any debris that may obstruct the installation of the new cartridge. Lubricate the rubber parts of the new cartridge with silicone grease. Insert the cartridge into the valve body so that the "H C" marking on the face of the cartridge is on top (hot is on the left and cold is on the right). Push in the cartridge as far as it will go.
Use the plastic adapter that comes with the new cartridge to help position the cartridge and push it into the valve body. Fit the adapter onto the cartridge and grip the adapter nut with pliers to rotate the cartridge as you push it in.
Install the Retaining Clip
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 adapter or a Moen cartridge puller. Note: Do not try to force the clip into position; it should slide in easily.
Make sure the retaining clip is fully seated, then slide the chrome sleeve back into position over the cartridge
Reassemble the Handle
Fit the two pieces of the temperature limit stop kit back into place, keeping the pieces in the same orientation as before. If necessary, you can change the temperature setting now or after the water is back on (see below). Fit the black handle adapter onto the cartridge, using the original orientation, and secure it with its screw. Fit the handle onto the cartridge stem, and secure it with its setscrew.
Turn the water on and test the faucet to make sure the valve gets cold first, then warmer as you rotate the handle.
Adjusting a Moen Scald Guard
The temperature limit stop kit is the device behind the scald guard feature on some Moen shower valves. It limits how far the handle can turn in the hot direction to prevent accidental scalding. You can adjust the setting of the limit to fine-tune the temperature for your house.
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 outer white piece to the right to limit the hot water. 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 outer 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.