I have a toilet that would not stop running. I replaced the flush valve with no luck. Then, I replaced the remaining parts with like parts via a “toilet repair kit” by PerformMAX (#402CARHR). I have a shaft with what they call a float cup (vs. float arm) that moves vertically along the shaft until the float rises high enough to shut the water off. Unfortunately, the new part seems defective. The float does not fully shut off the water. There is an adjustment screw, but that does not seem to make a difference. It seems it cannot be screwed down anymore. (Screw up lets in more water into the tank.)
Two questions:
a) it says the top of the fill valve cap should be about 3" above the top of the overflow pipe. How critical is this? If the cap were too low, I imagine the water level in the tank would not come up as high as maybe it should. I don’t think this is my problem.
b) Could I have a defective fill valve? When I pull up on the lever (attached to the float), the toilet is still slightly running.
Lift up the float (with your hand). If you lift it up all the way, does the water shut off? It sounds like from your description that the water doesn’t shut off when you do this. If so, then yes, the valve is defective.
If you have it adjusted wrong, if the water starts going into the overflow pipe before the float shuts it off, the toilet will run forever, since the overflow will prevent the water level from ever rising to the point where the float can shut it off. You need to adjust it so that the float turns off the water before it reaches the level of the overflow.
Just wanted to come back and say it was a faulty flush valve after all. It was annoying having to buy another and re-install hoping the problem won’t repeat. Thanks again for your thoughts.
If your new toilet guts include instructions to snap off the valve’s cap and let water geyser up for a few seconds, follow them! This flushes any little bits of junk out of the mechanism. (And yes, the PerforMAX has such instructions.) It’s entirely possible the OP’s new valve was fine, except for a stray trimmed-off plastic chip from the manufacturing process.