If you're involved with a Moen kitchen faucet repair, and the faucet has only one handle, the job will entail taking the faucet apart. That might sound drastic, but it's actually pretty simple — which is also is true, by the way, for a Moen single handle bathroom faucet repair. If there is any complication, it will probably be caused by scale build-up.
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If you take apart a faucet from another manufacturer, such as Delta, you're as likely to find a ball valve as you are to find a cartridge valve, but that's not true if the faucet is a Moen. All Moen faucets, even the two-handled models, have cartridge valves. If the faucet is leaking, you might have to replace the cartridge. But it's also possible that replacing O-rings will stop the leak.
Faucet Is Leaking from the Spout
Some Moen cartridges, such as the ones in Positemp shower valves, can be large and complicated. But the ones in kitchen faucets are smaller and simpler, and they are usually made of plastic. When the spout leaks, water may be slipping past the O-rings around the cartridge or through the cartridge itself, and when the latter malfunction occurs, it's often because mineral deposits are preventing the cartridge from sealing.
You may need to replace the cartridge, but you can often fix the problem by soaking it overnight in vinegar to dissolve the minerals. If you need to replace the cartridge or the O-rings, you'll need the name of the faucet model so you can order the proper parts from Moen. If you don't know the model, you can look it up on Moen's site, which also provides information on exchanging the O-rings.
You'll need a flat-head screwdriver, hex wrench and pair of locking pliers to remove the valves so you can determine what needs to be done. Turn off the shut-off valves under the sink, pop off the cap from the handle with the screwdriver, unscrew the set screw with the hex wrench and pull off the cap to expose the valve retaining nut. Loosen and remove this with the pliers and pull out the valve.
Moen Kitchen Faucet Leaking from Base of Spout
If you have a faucet that swivels, and it leaks from the base of the spout, the problem may also be worn O-rings, according to Moen's troubleshooting page.
To access the O-rings, you need to remove the spout. You can do this without removing the valve, although you do have to remove the handle. Once the handle is off, grasp the spout and lift it right off the faucet base, tapping with a mallet if necessary to loosen it.
You'll see the O-rings fitted around the faucet base, and you can usually pry them off with your fingers, using a screwdriver if necessary. Before you get to this point, you should have your replacement O-rings in hand. Moen recommends lubricating them with silicone-based grease — not ordinary plumber's grease — to make them watertight and easier to install.
Faucet Is Leaking Under the Sink
When a swivel faucet is leaking from the base, some of the water may drip underneath the sink. You fix this by replacing the O-rings.
If you have a Moen pull out kitchen faucet leaking from the base, however, the problem could be that the quick connector between the spout hose and the faucet base is leaking. That isn't supposed to happen, and when it does, it's usually because the connecter wasn't put together properly.
Moen's instructions for fixing this problem begin with finding the tabs or button on the connector and squeezing while you push the hoses together. This releases the connector, allowing you to pull the hoses apart so you can start over. To reconnect the hoses, squeeze the tabs again, push the male end into the female end until the connector clicks and the tabs come out all the way. If the connector has a push button, there's no need to press it. Just listen for the click.
Chris Deziel is a contractor, builder and general fix-it pro who has been active in the construction trades for 40 years. He has degrees in science and humanities and years of teaching experience. An avid craftsman and musician, Deziel began writing on home improvement topics in 2010. He worked as an expert consultant with eHow Now and Pro Referral -- a Home Depot site. A DIYer by nature, Deziel regularly shares tips and tricks for a better home and garden at Hunker and Family Handyman.