How to replacing a tank ball?
The toilet comes on by itself, runs for a few seconds, and then shuts off. You may also signal a bad flush valve, but check the flapper/ball first. In any case, a small stream of water is leaking through the valve. As the tank level drops, the float activates the fill valve, which replenishes the lost water and then shuts off.
When a flapper or tank ball fails, it's usually because the rubber has broken down. In the worst cases, the flapper will literally fall apart in your hands. An early warning sign of deterioration is a stubborn black slime that covers the surface of the rubber.
Replacing the parts is cheap and easy to do. Flappers and tanks are universal, so just about any brand will work. Chlorine degrades rubber quickly, so if you use chlorine toilet-tank treatments, it's a good idea to install a flapper or tank ball made to resist chlorine.
To replace a tank ball, first shut off the water, and grip the top of the lift wire with pliers. With your remaining hand, thread the ball from the lift wire. If the ball crumbles, leaving only the brass insert attached to the wire, use a second pair of pliers to grip this fitting. Brass is soft, so you won't have any trouble blacking the ball fitting from the lift wire with a good grip. Again, dress the flush-valve seat with an abrasive and a paper towel; then insert the wire through its guide and into the new tank ball. Finally, make any needed adjustments in the lift-wire guide.
If the flapper seems to be in good shape and a good seal, the problem lies with the flush valve, and you'll have to replace it.
1. To replace the tank ball, first drain the water from the tank; then hold the ball with one hand and the lift wire with the order. Unthread the ball from the wire. If the two won't separate, hold each end with pliers and turn.
2. To install the new ball, slide it into place above the flush valve, and thread the lift wire down through the hole in the support arm and into the top of the ball. This ball has a weighted bottom to help it seat in the valve more easily.