1. Toilet fill valves wear out eventually. They can be repaired, but it’s easier and a better fix to just replace them. Before removing the old fill valve, shut off the water supply at the fixture stop valve located on the tube that supplies water to the tank. Flush the toilet and sponge out the remaining water. Loosen the nut and disconnect the supply tube, then loosen and remove the mounting nut.
2. If the fill valve spins while you turn the mounting nut, you may need to hold it still with locking pliers. Lift out the fill valve. In the case of an old ballcock valve, the float ball will likely come out as well. When replacing an old valve like this, you will likely also need to replace the flush valve.
3. The new fill valve must be installed so the critical level (“CL”) mark is at least 1″ above the overflow pipe (see inset). Slip the shank washer on the threaded shank of the new fill valve and place the valve in the hole so the washer is flat on the tank bottom. Compare the locations of the “CL” mark and the overflow pipe.
4. Adjust the height of the fill valve shank so the “CL” line and overflow pipe will be correctly related. Different products are adjusted in different ways – the fill valve shown here telescopes when it’s twisted.
5. Slip the valve’s threaded end down through the tank. Push down on its shank (not the top) while tightening the locknut (inset). Hand tighten, then use a wrench to make an extra 1/4 turn. Hook up the water supply tube, and tighten in the same way.
6. If the overflow pipe has a cap, remove it. Attach one end of the refill tube from the new valve to the plastic angle adapter and the other end to the refill nipple near the top of the valve. Attach the angle adapter to the overflow pipe. Cut off excess tubing with scissors to prevent kinking.
Warning: Don’t insert the refill tube into the overflow pipe. The outlet of the refill tube needs to be above the top of the pipe for it to work properly.
7. Turn the water on fully. Slightly tighten any fitting that drips water. Adjust the water level in the tank by squeezing the spring clip on the float cup with needlenose pliers and moving the cup up or down on the link bar. Test the flush.