Stem Faucet Clinic
Basic steps for faucets & valves
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:
- 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
- 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).
- 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 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.