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Stem Faucet Clinic

Basic steps for faucets & valves

by Gordon Bock & Jeff Wilkinson

Scores of different faucet designs have found their way into houses since the time indoor plumbing was first .introduced. Early, simple types, such as the ground key and Fuller ball, are now largely obsolete and exist only in very old systems or out-of-the-way locations. The faucet types currently in production, chief among them the disc, ball, and cartridge, are modern, sophisticated devices developed over the last 50 years and not original equipment in most old houses. The long-standing workhorse of the plumbing industry is the stem faucet (also known as the compression faucet), which was common by the turn of the century and is still in wide use today.

Stem faucets are straightforward mechanisms that employ a threaded stem to bring a washer in contact with a seat, thereby restricting or interrupting the flow of water. This arrangement is also widely used in globe-type valves located in-line throughout a plumbing system, and is therefore almost always the most well represented shutoff in any house. Stem faucets can wear and start to leak, as will any working housepart that receives hard service. Every faucet is a little different, but fortunately, their simple construction and time-tested design make problems simple to diagnose and cure. The next time a stem faucet needs a checkup -- or major surgery -- here's how to operate:

Washers

  • Washer replacement is a routine maintenance procedure. Replace washers that are split, eaten away, or no longer pliable. Continued use of leaky washers wastes water and erodes channels in the faucet seat. Keep assorted washer sizes on hand for on-the-spot repairs.
  • Replacement washers should always be the correct size and shape for the faucet. Flat washers are designed for seats with crowns or ridges, tapered or rounded washers are for tapered seats. Washers that "almost fit" seldom work for long, and some faucet problems stem from just using the wrong washer. Choice of washer composition is a matter of preference. Flat, neoprene rubber washers make up the majority sold today, but Teflon and synthetic fiber washers are also available.
  • To disassemble the faucet and gain access to the washer:

1. Shut off the water supply to the faucet.

2. Remove the faucet handle, normally secured to the stem with a screw hidden under a decorative cap. Difficult han-dles may require a faucet-handle puller (similar to a min-iature gear puller). Faucets with long stems may not need their handles removed at all ff there is room to swing a wrench on the cap nut.

3. Back off the cap nut with a parallel-jawed wrench, such as a monkey wrench or adjustable (Crescent) wrench. To avoid marring the finish, first wrap the nut in electrical tape or cushion it with a rag; never use toothed-jaw tools such as waterpump pliers.

4. Replace the faucet handle temporarily and open the faucet to back the stem out of the faucet body.

  • Use care when removing brass washer retaining screws; old screws may be brittle or have worn heads. A drop of kerosene or penetrating oil may help loosen difficult screws. Also remove any mineral deposits from the stem base or screw area before installing washer and new screw. For long-term service, change screw as well as washer.
  • When investigating leaks in mixing faucets, which in-corporate both hot- and cold-water inlets (such as on bath-tubs), start by checking hot-water washers. These invariably fail first due to the temperature and slightly caustic effect of heated water.
  • Faucet leaks may not be the fault of washers alone. If washer replacement stops a leak only for a short while (or not at all), suspect a nicked or worn seat (see below).

Seats

  • Inspect seats visually by looking inside the faucet body with a flashlight. Healthy seats look smooth; those with defects show cracks, fissures, or pits. Damaged seats can be replaced (if removable) or dressed (if part of the faucet body).
  • Removable seats are unthreaded and reinstalled with a valve seat wrench, a straight or L-shaped bar ground at the ends to fit into either a square or hex-agonal hole in the seat center. If not badly worn, removable seats can be restored by carefully dressing the face flat again with a fine file or wet-or-dry sandpaper.
  • Non-removable seats may be dressed with a seat-dress-ing tool that acts as a rotary file. Individual tools vary in design and operation, but all fit into the faucet body, re-placing the stem so that the cutter can be rotated on the seat with a wheel handle (much like a faucet handle) until the seat face is smooth. Use the proper-size cutter for the seat, work with moderate pressure (seats are brass and soft), and flush all cuttings from the body before reassem-bling the faucet. Seat dressers are not always successful, but they're worth the investment (under $15) if they save the cost of buying a new faucet.

Stems

  • Stems last a long time under normal wear conditions, but if they are allowed to close re-peatedly on severely deteriorated seats or wash-ers, they too may become damaged and require replacement. Worn or bent stems also may cause damage so that the faucet must be replaced.
  • The dimensions of faucet and valve stems are critical and the variety of replacements is bewil-dering. Always take the damaged stem along when securing replacements, and compare every aspect to make sure the fit is correct. Good hard-ware stores and plumbing-supply houses carry common stem varieties; specialty plumbing sup-pliers or salvage yards may have old or odd-sized stems.
  • When installing a replacement stem, replace the seat as well (if possible) to avoid premature wear. Coat the thread lightly with petro-leum jelly for smooth action.
  • Leaks where the stem passes through the cap nut Can be caused by either a loose cap nut or com-pressed or worn out packing. Loose caps can be tightened just enough to stop the leak. (Overtightening will cause excessive wear in the packing.) Compressed packing can be improved by wrapping a turn or two of braid packing (sold at most hard-ware stores) around stem in the direction in which stem moves when faucet closes. If leak persists, replace packing.
   



 
 

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