Trickle of water from tank into bowl

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Flyover

Trying not to screw things up worse
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The toilet in my kids' bathroom had this constant trickle of water flowing into the bowl, even after I'd taken the flapper off and cleaned it. Then the fill valve started hissing, and taking the cap off revealed there was water spraying out of some internal part that had broken.

That was as far as I cared to investigate; I decided it was time to replace all the toilet's guts.

So today as I was standing in the plumbing aisle at the hardware store, I had fond memories of the dual-flush ecotoilet in our previous house. With that on my mind, I decided to spend the extra $15 for a similar setup that could be retrofitted to the toilet presently in question. Surely this will pay for itself over the long term!

After two hours, a bit of cursing, a slightly sore back, and another trip to the hardware store to get a more modern flexible supply line -- but with high spirits because I actually enjoy home plumbing projects like this -- the Danco Next dual flush total repair kit (this exact model) was installed.

...but the trickle remained. As directed on the troubleshooting page in manual, I removed the top portion of the flush valve and made sure the bottom portion, with its dome-shaped gasket, was properly seated in the fitting in the bottom of the tank. I also ran a finger carefully around that fitting to make sure there was no slime or grit or other obstructions. I checked everything a lot more thoroughly this time and even filled the tank with about an inch of water, enough to look down the middle of the gasket and watch whether any was dripping through. I also checked in the bowl. Nothing. So I tightened everything down, reinstalled the upper portion, and refilled the tank.

Now it's trickling again, and I'm ready to punch someone. So instead I turn to You, O Forum. Help me!
 
I might be on the wrong track here but is it possible the fill valve needs to be set to a lower height in the tank? I’m basing this on the possibility that it’s not the flapper that’s leaking but the fill valve not able to rise to a height high enough to turn off.

Also, what is the water pressure in your house?
 
I set the fill valve level with the top of the tank as directed, and this also allowed the fill line to come up to about 1/2" below the overflow pipe, also as directed. If I set it any lower then there isn't enough water for the blue float in the flush tower to float at 1/2" below the full water line as directed, and I just barely get it there if I set it all the way down on its calibration strip. Makes makes me wonder if I have a smaller-than-standard tank. But it doesn't seem like it since A) it's the same size as most every other toilet tank I remember having and B) the kit installed in it just fine. Maybe I have a shorter-than-standard overflow pipe??

Anyway, the valve definitely rises high enough to turn the water off. I can tell there's no more water coming into the tank once it's full. The problem is the water leaking out of the tank!

I'm not sure what the water pressure in my house is. I don't know if this is relevant, but I've got the supply line to the toilet choked down to where it's only maybe a half-turn or three-quarter-turns on, because if I open it any more then it starts dripping. The valve there looks pretty old; it's covered in oxidation.
 
Did you already change the flapper, or did you just clean it?

Replace the flapper, they can look fine and still not seal well onto the flush valve.

Or, buy a new Fluidmaster or Korky flush valve.
Which will also have a new flapper on it.

There is possibly a small crack somewhere in the plastic of the old flush valve.

Or the face of the valve has burrs or pits.

Or the gasket is deformed.
Chlorine can damage the old gasket or old flapper.

You can also add teflon pipe dope all over the gasket of the old or new flush valve, and on the threads going into the gasket.
 
@Jeff Handy the new dual flush system doesn't have a flapper. Check out the link in the original post. It's a system that uses a gasket. And no, the gasket isn't deformed, it's seated exactly to spec.

But yeah, someone else (outside this forum) also suggested I get a new flapper and test it with that to see if it's the seat that's the problem. Or that it might be a crack in the overflow pipe.

Now, adding teflon pipe dope...that sounds like it might be helpful. Tell me more about that!
 
I always add teflon pipe dope to the threads of any penetration like that.

So if water from the tank sneaks past the gasket seal, it still has a chance of being stopped from going through the threads.

I also add pipe dope when I am bolting the tank to the bowl, and a thin layer under the washers.

That is a very similar situation to installing a drain in a bathroom sink.

Meanwhile, since the flush valve is all new, maybe the trickle is just from the fill valve, from the bowl refill hose.
Which means the fill valve is not shutting off 100 percent.
 
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I just checked out that Danco system.

How does the flush valve attach without removing the bowl, does it just jam into the base of the old flush valve?
 
I had the same problem. For peace of mind, I installed a new fill valve as the float on the old one was sticking. When I flushed, the float valve did not drop for about 5 seconds. The flush valve, cannister style with a Kohler toilet, had a bad seal I later found out. I could hear water trickling and then at some point, as the float valve slowly dropped, the fill valve would turn on to replenish the lost water. The seal looked good on the flush valve but after replacing it, the leaking of water from the tank stopped. Kohler or someone had come out with a better quality seal. I don't know the specifics but it is supposed to hold up better against age. I know you don't have the cannister style flush valve but as Jeff mentions, it either has to be the seal of your flush valve not seating properly because either that style flush valve isn't appropriate for your tank doubtful) or the tank hole area has pitted or eroded over time and not flush valve will seat properly. Using pipe dope would be a good option. If that fails, it might be time to replace the toilet. That Danco system looks interesting but in my opinion a bit over kill especially for a kids bathroom. I hope you get it working. Oh, here is something I didn't know about until I accidentally came across it. For my toilet, I have a 3" diamater flush valve. I almost bought a 2" diamater not really knowing what I was looking at. Make sure that the size you installed is actually the size you needed.
 
It's a long shot, but has happened to me in the past... Installed a new ballcock and pushed the fill hose into the fitting on top of the overflow tube. The tip of the fill hose was just slightly below the water level in the tank. Because it was lower it allowed water to siphon back down the overflow causing a very slow dripping into the bowl. Just something to think about. Now I always use the plastic piece that comes with the new ballcock.
 
Johnboy is right, I have encountered that siphoning from the bowl refill hose also.

The clip stops that, and also prevents the occasional leak/flood if the refill hose pops loose from the overflow tube, and starts spraying outside by getting water past the tank lid.
 
Fixed it. It was the gasket on the tank side of the flush valve.
 
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