Just about every household has had a clogged toilet and most reach for the plunger and that’s the end of it. But other toilet troubles can occur that require a bit more investigation, and sometimes replacement parts are necessary.
When a toilet runs continuously, the tank ball is not sealed against the valve at the bottom of the tank and this is what allows the tank water to flow into the bowl, keeping the float from rising high enough to close the incoming water supply valve.
To begin, flush the toilet while looking into the tank, observing the various linkage arms and guide wire for freedom of motion. If the tank ball does not drop down freely or if it drops but does not appear to be settling itself properly into the valve seat, the trouble is likely to be the guide arm, lift wires, or the ball.
Adjust the guide arm so that it is directly centered over the valve seat. This arm is held fast to the standpipe and can be loosened enough to adjust with a screwdriver.
If the lift wires are bent, they should be replaced. Replace the ball valve also if it shows signs of wear. Turn off the water supply to the toilet and unscrew the ball from the lift wire. If the valve seat shows signs of mineral deposit build-up, sand the perimeter of the valve seat with #500 emery paper. Ball valves, lift wires and other toilet parts are available at the local hardware store or home center. Take the old parts to the store for accurate size comparison.
Next, check the level of the water in relation to the height of the standpipe. The water level should be between 1″-2″ inches below the top of the standpipe. If the water runs over the top of the standpipe, it will flow directly into the toilet. The float rod can be adjusted by bending it a small amount. This method works well with ball-cock valves made of cast, but not with those made of plastic. Plastic ball-cock valve floats can be adjusted by turning the Phillips head adjustment screw located on the top of the valve assembly. Clockwise turns will raise the float and counter clockwise turns will lower it.
The entire ball-cock assembly can be replaced by turning off the water supply, flushing the toilet, and soaking up the remaining tank water with a sponge. Remove the water supply line from the toilet tank with an adjustable wrench, followed by the removal of the valve retaining nut. Lift the old valve out and install the new valve along with its seal. Attach retaining nut and the water supply line and restore the water supply to the tank.
Remember, always work safely.