Try some dye to diagnose a sneaky toilet leak

Q: We have a sneaky 37-year-old toilet.

At night, I've noticed that there is a very faint sound of running water coming from the water tank even though it was not running when I went to bed.

I've spent a lot of time trying to adjust the float and have replaced the innards (except the float) three times. Should I give up and just buy a new fixture?

If I buy a new toilet, can I get the kind that has a two-button flush (and saves water) without having the plumbing under the floor replaced?

A: If you have adjusted the float correctly, look to the flapper valve as the culprit. These routinely leak even when newly replaced.

A bit of food dye in the tank will reveal in a few minutes if water is leaking into the bowl. (You'll see water running into the bowl if the float or the valve is bad.)

If you need a new valve, try to take the old one to the hardware or home-improvement center so you can find the correct replacement.

Installing a dual-flush toilet sounds like a great idea. Replacing an old toilet with a dual flush is no different from any other toilet replacement — simply bolt the new rig into the existing plumbing.

Check with the manufacturer's literature to be sure that everything matches up correctly before making a purchase.

Q: I have recently installed French doors in an extremely rainy, windy location on the north side of a home. I would like to paint the fiberglass on the outside of the doors to match the rest of the home. Paint dealers have told us we can do this by using an acrylic primer followed by the paint of our choice. The concern is that this finish would show brush marks and chip off easily. Will we be happy if we paint the doors?

A: First, consult the manufacturer and/or the finishing instructions that came with the door for any specific dos and don'ts as far as primer and paint types. Then get your hands on the highest-quality paint you can find, and do not skip any priming or preparation steps.

Brush marks are less likely with oil-based paint, a good brush and an even hand.

You also can avoid brush marks by using a mini-roller or sprayer.

For best results, take the doors off the hinges and paint the jamb and doors separately. Do several light coats to avoid runs. Enjoy your new doors.

Darrell Hay is a local home inspector and manages several rental properties. Send home maintenance questions to dhay@seattletimes.com. Sorry, no personal replies. More columns at www.seattletimes.com/columnists.