Do It Yourself

Q: We sometimes get a strong sewer odor in our house, especially when we run the washing machine. Someone told us the traps to some of our drains might have dried out, letting sewer gas enter the house. What are your thoughts?

A: Sewer odor can indeed come from empty drain traps. Each of your drains has a trap that is designed to retain some water and prevent sewer odors from passing through to the living area. If the water drains out of a trap, the odor will come through. Water can leave traps for several reasons, such as leaks, evaporation and more complex plumbing problems. Vent pipes, which help expel sewer gas to the outside, can also cause an indoor odor problem if they become blocked or cracked. Vent pipes extend through the roof of the house and sometimes become blocked with debris like leaves or a bird's nest.

However, because your odor is associated with the washing machine, I suspect bacteria in the washer's drain system are the cause. Try replacing the hose that carries drain water from the washer after clothes are washed. If this helps but doesn't eliminate the problem, fill the washer with water, add about a quart of chlorine bleach, and flush out the washer's drain system. Run a couple of cycles with clear water afterward to rinse out the bleach.

As for traps, leaks are usually obvious and so is the solution: repair or replace the leaking trap. Evaporation of water from a trap is most likely if a fixture has not been used for an extended period during dry weather.

Check for drained traps by pouring a quart or so of water into each of your bathroom fixtures and see if the odor fades or disappears. If the odor leaves but returns, suspect a vent problem and call a plumber.

Q: How do I hide knots on painted woodwork without refinishing the entire piece?

A: I don't know of any practical way to hide the knots permanently without refinishing the piece, unless you are very good at touching up finishes. The knots likely were not sealed when the woodwork was originally painted, and they have "bled" through the paint. If you simply paint over them now, they will bleed through again.

The best treatment is to seal the knots with de-waxed shellac or, better, use a shellac-based, primer-sealer stain killer sold at many home centers and paint stores. Let the sealer dry thoroughly and either repaint or touch up the sealed areas.

Q: I need to install some new parts in a toilet with an inlet valve that is frozen open. I have thought of using a monkey wrench with a pipe extension on the handle to free the valve but am afraid of breaking it. Any ideas?

A: I certainly would not try using a pipe extension on the handle of a wrench to free the valve; that would be using far too much force.

Try squirting some penetrating oil on the stem of the valve so the oil seeps into the body of the valve. Penetrating oil is sold at most home centers and hardware stores. Apply the oil once or twice a day for several days.

Next, loosen the packing nut on the valve slightly. It might drip, so put a bowl underneath to catch the water.

Finally, try to close the valve by hand. If it is still stuck, use a pair of adjustable pliers to try to gently turn the handle, applying only moderate force. I have opened several frozen valves this way without damaging them.

If that doesn't work, call a plumber. Incidentally, I recommend closing and re-opening shutoff valves at least once a year to keep them in working condition. In an emergency, a frozen valve can cause a lot of damage.

Questions and comments should be sent to Gene Austin, 1730 Blue Bell Pike, Blue Bell, Pa. 19422. Send e-mail to doit861@aol.com. Questions cannot be answered personally.