Installing and Repairing a Fill Valve

Insert the new float-cup assembly through the hole in the tank. Hold it in place and tighten the mounting nut under the tank, following the instructions with the assembly. Make sure the cup is clear of obstructions.

Remove the flapper or stopper. Slide the new flapper down the overflow tube and adjust it so it sets down onto the center of the flush-valve seat. Attach the chain to it with about 1/2 inch of slack.

Clip the refill tube to the overflow pipe. Reattach the supply tube and turn the stop valve back on. Let the tank fill and then check for leaks.

Replace the rubber parts of a ballcock valve if they are damaged. Remove the float-rod linkage, which is attached with two screws. Pull out the plunger with pliers.

Clean away sediment in the valve, using a toothbrush or a soft wire brush. If the O-rings and the seat washer are worn, you may find it difficult to find replacements. Buy a new float-cup assembly if necessary and replace the entire assembly.