This one has me scratching my head. The toilet started “running” after flushing and filling. This is not a problem with the flapper, but rather with the float/refill mechanism. Basically, the arm attached to the float is sticking, which allows water to continue to run into the overflow.
So I ordered a new assembly, and in the meantime left the porcelain lid off the toilet tank so we could manually lift the arm fully up. Well, it quit having problems after a day or so, so I put the new assembly aside to see what was going to happen. It kept flushing normally, every single time. Okay, so it’s a temporary glitch. I put the lid back on the tank and things go along just fine.
Then it starts acting up again. So I remove the lid and figure I’ll do the job the next day. But the problem stops immediately. Put the lid back on, the problem starts up again after a short while. Take it off, problem stops. WTF? My spouse says “maybe it’s moisture causing the problem”. It’s a fookin’ toilet says I: it’s supposed to be wet.
My first guess is that the lid is preventing the float from going up as high as it needs to. It might be that the fill valve is worn and requires the float arm to go higher than it used to in order to shut off. This may only apply to this type of float and arm, where the float can definitely hit the lid. If that’s what you have, judicious bending of the float arm may solve the problem for a while, but probably a new fill valve will be needed eventually.
The seal for the float valve may be iffy and giving it a nudge allows it seal for a while. Bending the arm to put a little more closing force on the valve may do the job.
Maybe it’s scared of the dark. I suggest you put a light inside the tank…
Other then that, I’m thinking it’s just on the verge of completely failing or something inside the valve is just barely at the point of not working. The fact that it seems to work with the lid off is probably a coincidence.
There’s probably a mineral buildup at the on/off valve inside the unit. If you read the instructions on the replacement unit, you may find it suggests cleaning the unit periodically along with instructions to accomplish this.
I would not hesitate to install the new unit because the old one could seriously malfunction at any time.
As for an explanation, it still might be that the vertical rod that connects the float to the fill valve is hitting the lid, and that it needs to go higher than it used to due to wear in the fill valve. As for fixing it, with that design there’s really nothing to do other than replace the fill valve.
Actually, with most of that type valve, you can adjust the height by screwing the entire upper assembly up or down. If that is the case, try giving it one complete turn to lower the valve head, and see if that helps. You will have to re-adjust the fill level afterward.
The only problem I’ve had with those is that little clip rusting off. Then one day I’ll hear an odd noise, open the lid and get sprayed with water by the rubber hose which is now not attached to anything.
