My new toilet is sometimes running but removing the lid solves it

Question

This is crazy but I reproduced it multiple times: from time to time the toilet won't stop running , I think a non-complete flush will trigger it. If I just remove the lid and flush again then it'll stop and work without a hitch for weeks. What gives?

Answer 1

This actually isn't too uncommon. Like dandavis said, it's likely the "fill is proud of the tank rim" — or, to translate: The shutoff lever attached to the ballast was installed too tall. Here's a picture to illustrate:

Long story short, the ballast floats up as your tank fills with water. At the top of the ballast is a stick that attaches to a lever controlling the water release; called, conveniently enough, a float valve. Unfortunately, if the stick is too high then the lid prevents it from activating the lever and disabling the water.

Taking the lid off "fixes it" because it's not really broken, these things are just cheap and imprecisely manufactured. So you reset the height of the ballast by taking off the lid, and allow the valve to final fully shut. But over time, things wiggle apart again. The valve loosens, the stick misaligns, and the ballast sinks.

Easy fix though… The ballast is held in place by either a pin or small screw. Simply turn off the water, then flush the toilet to drain the tank. Remove the connector and lower the ballast by ¼-⅛ inch, and reattach it. Problem solved!

Alternately, you can raise the lid by the same height, but I dislike how wobbly that makes it feel. Plus, if the lid falls off and breaks, you're out a lot more money than the time it would've taken to fix the ballast height.

Here's some additional resources on this. diy.stackexchange

home-repair-central (image credit belongs with this website, since I couldn't upload my own)