Toilet internal leak: is flapper the only possible culprit?

Toilet in a tenant's apartment. This is the type of internal leak that causes the float to drop which makes the tank refill periodically.

I know that a defective flapper is the most likely candidate, and I will be looking into this tomorrow. Will check the flapper itself, as well as the part it seals to, for damage, mineral deposits, etc.

But this flapper is relatively new, it was installed only about a year ago. So I am wondering if any of the other parts inside the tank could possibly be causing this leak?
 
I had a toilet running a couple weeks ago and when I took the lid off, water was overflowing into the overflow tube which goes into the bowl of course. Why? The place where the float rod attaches to the valve had busted - plastic was still hanging on but was acting like a hinge, so the float just went higher rather than shutting off the fill valve. You'd know right away because water overflows into the drain tube and it should shut off before it gets that high.

I had some old Mansfields that had a rubber gasket for the flapper to seal against, and we'd have to replace them periodically. Cost about a buck. Depends on how yours is designed.
 
No water on the floor. I haven't kept any records, but this particular toilet seems to always be needing new parts. I know that it has had new flappers 3 or 4 times, and IIRC the fill valve was recently replaced. Flappers are not expensive, but this is starting to feel like a recurring problem.

I will take a good look around inside it tomorrow, in particular the flapper seal area.

Thanks everyone...
 
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There's also a seal between the tank and the bowl (below the flapper). If this is leaking water goes to the bowl, not the floor. But they usually don't go, usually when they are replaced they will leak if the fill tube isn't tightened enough.
 
No water on the floor. I haven't kept any records, but this particular toilet seems to always be needing new parts. I know that it has had new flappers 3 or 4 times, and IIRC the valve was recently replaced. Flappers are not expensive, but this is starting to feel like a recurring problem.

I will take a good look around inside it tomorrow, in particular the flapper seal area.

Thanks everyone...

One more thing - I bought a couple of the more expensive toilet kits and both of them had failures within a year. I bought the cheap stuff, threw out all the fancy, adjustable stuff and the cheap-o flapper/arm have been running flawlessly for a few years. FYI.
 
There's also a seal between the tank and the bowl (below the flapper). If this is leaking water goes to the bowl, not the floor. But they usually don't go, usually when they are replaced they will leak if the fill tube isn't tightened enough.

I have replaced that gasket in three toilets in my Mom's house which was built in 1970. Those three didn't leak, but they were disintegrating and turning water in the bowls black. I will keep that seal in mind when investigating this current issue.
 
Sometimes the plastic/nylon seat that the flapper seals against gets a rough spot or mineral deposit on it that prevents the flapper from making a tight seal.
Usually you can lightly sand it or rub it with a Brillo pad to make it seal again.
The really old ones were brass but that’s 40+ years ago.
The rubber tank to bowl donut will leak on the floor if loose as will the tank to bowl hold down screws/bolts’s rubber washers so it can’t be those.


Bob
 
Sometimes the nylon seat that the flapper seals to, will build mineral barnacles and allow a very small trickle to escape the tank.if you're replacing the flapper valve annually, replace that whole overflow/flapper valve and the tank to bowl bolt/rubber washers. It's a little more labor and more in parts, but you won't be running back every year or less to replace the flapper.
 
I had the same problem 2 weeks ago. It had a small leak that you could barely hear but it would make the tank refill about every 2 hours or so. Turned out to be the refill valve so I replaced the whole unit. It took care of the problem and took me about 20 minutes. Got a new one at Lowes for about 16 bucks.
 
I had one where the chain would sort of twist up and make it too short for the flap to go back down. Just carefully rearranged the length and everything went back to working just fine.
 
I helped my landlord rehab both our bathrooms a few years back, I used the tablets in the tank in my bathroom, he did not in his. My flapper failed within a few years. It was an "aqua source" toilet from Lowe's and I replaced the whole mess with Fluidmastr stuff and it's been fine since. I stopped using the tablets after that experience, better to just use a toilet brush.
 
ive had a few leak in buildings from the water level being set to low or jars inside to save water, usually on the 3 gallon or 5 gallon flush toilets, not enough water weight to push them down tight. also have had the nut on on the bottom of the tank the holds the flush valve in loosen or the gasket under the seat wear out , thats right under the seat that the flapper is sitting on not the gasket between the tank and bowl, and water will leak under that and go into the bowl. assuming your flush valve is plastic but the older ones made of brass the overflow tube itself can leak where it screws in or they can even crack. the main cause is a dirty seat though so make sure you use a scour pad to clean the seat before you put the new flapper on. when your done put some food coloring in the tank dont flush and check the bowl after maybe 20 min if the bowl water has turned the color of the food coloring you still have a leak
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flush valve
 
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I had one where the chain would sort of twist up and make it too short for the flap to go back down. Just carefully rearranged the length and everything went back to working just fine.

Nothing worse than a twisty! The guys will know what I'm talking about. :smoke:
 
thanks for all the informative and helpful responses...


So today I shut of the supply and emptied the tank. The old flapper had significant mineral deposits, which would make me think that the leak was through that seal. But the mating surface, the hard plastic rim that the flapper rests on, looked clean. Even though it appeared clean, I kept that mating area wet with CLR for about 4 hours then wiped it down thoroughly with a Scott-Brite pad, after which I could neither see nor feel anything on it. But with a new flapper there was still a slight dribble into the bowl, even 30-60 minutes after a flush.

So, not really sure exactly where it is leaking, but is clear that the entire flush valve (as pictured in @Chrisxo55441 's post) will need to be replaced, and that means that the tank will have to be taken off. Did not have time to do that today, and probably will not do it for a couple weeks as other projects are more pressing currently.

Another question for you plumbing experts: will it be difficult to find the gasket (rubber ring) that mates tank-to-bowl for this old toilet?


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