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Leaking toilet - Flush valve or flapper?

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  • Aug 26th, 2021 12:31 am
[OP]
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Nov 23, 2010
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Toronto

Leaking toilet - Flush valve or flapper?

So recently my toilet on the second floor started to do "ghost flushing".

I thought to myself - Ah must be the flapper, let me go get one and replace it. Easy peasy.

Last night, I installed the flapper and was washing up when the toilet did another ghost flush. I was like wtf!

I did the routine - Turn off water main to toilet, flush toilet to empty tank, reached in to remove/replace the flapper and did a quick wipe of the inside of the flapper seat (or flush valve) to make sure nothing icky is stuck on it.

I did all of the above prior to installing the new flapper, and did it all over again a second time with a bit more of a thorough wipe of the flapper seat and same thing happened with a ghost flush.

Ok, so trouble shooting time.

I took the lid off, flushed the toilet and let it fill up. Marked where it was, and walked off. Came back 30 minutes later and noticed the water dropped and the toilet just so happened to "ghost flush" when I walked in.

Frustrated, I flushed the toilet one last time - Let it fill up - Then turned off the water inlet. Marked the water line again, and left it over night. I figured it would probably "leak" to where ever the leak was and then stop leaking.

I was thinking - Alright, leave it overnight and I was expecting it to leak UP TO the flapper seat line. So this would confirm its something with the flapper (maybe I got a defective one?)

On the other hand, if the tank FULLY empties - Then it may be something else more serious.

For good measure, I also dropped in some color dye to help visually see where a leak may be. If the inside of the toilet bowl changes color, then its a leak at the bowl. If I see color dye on the floor then I know its the other parts.

I still came back once more before heading to bed and confirmed that the water inside the toilet bowl changed color and nothing on the outside of the bowl. So its definitely something with the flapper or the flush valve.

Good enough, I go to bed and woke up expecting to see either the water leaked and stopped at the edge of the flapper seat OR the tank would be empty.

Neither of these happened! The water actually stopped about half an inch ABOVE the flapper???

Image


So now I'm a bit stumped?

Should I leave it for another day to see if any more water leaks out?

Not sure if its possible to lose lots of water at first then maybe slow to a super slow leak?

Obviously if its just a flapper issue, it would be a bit easier to deal with (buy another one). I really rather not change the flush valve as I havent done this before (it seems easy enough) - But my wife is pregnant and she is due any day now.

We have other washrooms we can use for now if baby comes in the next few minutes after this forum post so we are ok Face With Stuck-out Tongue And Tightly-closed Eyes

But again, I really rather avoid having to re-do the flush valve if I dont need to.

Also the house was built in 2006, and I moved in 2012. I replaced the flappers roughly in 2013 - I honestly haven't heard of the flush valve failing before. The toilet is an American Standard, and the internal parts all appear to be Fluidmaster, minus the flapper which I replaced with Korky and am replacing again with Korky.

I was just hoping for some way I can confirm where the leak is, or if I may have missed anything?

Any insight much appreciated!
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15 replies
Sr. Member
Jun 23, 2019
537 posts
394 upvotes
I had this exact same issue, the water level dropped to a level above the flapper. It turns out the round plastic tube (flush valve) was cracked at the bottom, so I ended up having to change the flush valve. Overtime the plastic got brittle and just me lightly touching it caused it to crack and leak.
Deal Expert
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Oct 23, 2008
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GTA, ON
Is it a universal flapper? Try a different type/brand. I know I had to try 2 or 3 before I got the right one.
Tis banana is IRIE 😎

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Deal Expert
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Sep 1, 2005
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Markham
Did you turn off the water before doing your leave it alone and see how far the water drops?
We're all bozos on the bus until we find a way to express ourselves...

Failure is always an option...just not the preferred one!
Sr. Member
May 6, 2010
930 posts
324 upvotes
Richmond Hill
Flapper.
try Korky flapper.
Deal Expert
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Jun 12, 2007
18590 posts
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London
Flip up the flapper.
Use your finger tips to feel around the the hard plastic edge of the tank drain that flapper seals against.
Check that the plastic edge is smooth and without any bumps or nicks
Deal Addict
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Dec 6, 2017
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Manitoba
Sounds like a flapper issue. I had an issue with the flush valve recently and the symptom would be water would keep flowing into the tank (and into the tank drain) continuously.
Deal Fanatic
Jan 21, 2018
7513 posts
8080 upvotes
Vancouver
Water gets from the tank to the bowl one of two ways: through the flapper at the bottom, or through the overflow tube at the top. The fill valve sends some of the incoming fill stream through a line into the top of the overflow tube - that's the part that fills the bowl while the rest is filling the tank - but that part won't pick up any dye from the tank.

So this is really simple. If the water level in the tank is not rising to the top of the overflow tube when it does these "ghost" fills, the water has to be going somewhere, and that somewhere can only be through the flapper into the bowl, which you have already confirmed with dye. If you want to be sure, shut off the water at the incoming water line valve with the tanks full, and watch to see if the level in the tank drops, which it must if the flapper is leaking.

So having confirmed that, you know that either your new flapper is not seating properly, or you have some much less likely problem like a damaged flapper seat, or a cracked overflow tube.
Jr. Member
Oct 22, 2020
110 posts
91 upvotes
Another failure point is the flush valve seat. That is sealed with a gasket against the tank ceramic surface. On my tank style, it is tightened by tightening a large plastic nut underneath the tank while it is separated from the bowl. Keeping everything centered as you tighten the nut is a challenge. I suspect when bolting the tank to the bowl, this also relieves some of the compression applied by the nut. I can't believe people haven't invented a better system (for example access that nut from the inside of the tank rather than outside). The parts are cheap, but it is a huge pain to take everything apart.
Deal Fanatic
Jan 21, 2018
7513 posts
8080 upvotes
Vancouver
kelaaa wrote: Another failure point is the flush valve seat. That is sealed with a gasket against the tank ceramic surface. On my tank style, it is tightened by tightening a large plastic nut underneath the tank while it is separated from the bowl. Keeping everything centered as you tighten the nut is a challenge. I suspect when bolting the tank to the bowl, this also relieves some of the compression applied by the nut. I can't believe people haven't invented a better system (for example access that nut from the inside of the tank rather than outside). The parts are cheap, but it is a huge pain to take everything apart.
But he says he doesn't see any water leaking and dripping on the outside, and he does see dye from the tank leaking into the bowl. That rules out leaking flush valve gasket in this case, and points the finger at a leak from the tank to the bowl.
Jr. Member
Oct 22, 2020
110 posts
91 upvotes
Scote64 wrote: But he says he doesn't see any water leaking and dripping on the outside, and he does see dye from the tank leaking into the bowl. That rules out leaking flush valve gasket in this case, and points the finger at a leak from the tank to the bowl.
Yes, the immediate path is from the tank down into the bowl. I'm not talking about the ring seal between the tank and the bowl. I'm talking about what is sealing that whole flapper plastic tree mechanism to the toilet tank.
Deal Expert
Jan 27, 2006
20511 posts
13894 upvotes
Vancouver, BC
vrscdx wrote: I had this exact same issue, the water level dropped to a level above the flapper. It turns out the round plastic tube (flush valve) was cracked at the bottom, so I ended up having to change the flush valve. Overtime the plastic got brittle and just me lightly touching it caused it to crack and leak.
Had that happen at my brother's house in a relatively new toilet. He likes using those store-bought cleaners that sit in the tank and 'cleans' the toilet with every flush. Unfortunately, that stuff also seems to weaken the plastic and deform the rubber parts as well.
[OP]
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Nov 23, 2010
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chimaican wrote: Is it a universal flapper? Try a different type/brand. I know I had to try 2 or 3 before I got the right one.
Yup its a universal "Korky" flapper, picked it up at Home Depot :)

I was debating whether to go to Lowes and pick up another flapper to give it another shot - Maybe I have a defective one some how?
gr8dlr wrote: Did you turn off the water before doing your leave it alone and see how far the water drops?
Yup! I turned off the water inlet and left the toilet overnight to see where the water level would drop to. It ended up stopping at maybe half an inch ABOVE the flapper. I thought it would either

1) Drop just below the flapper (implying its a flapper issue)
or
2) Tank would empty out, or at least be below the flapper line enough so I can see if its maybe the flush valve.

Again the odd thing was that the water seemed to stop JUST above the flapper - Not sure if I left it for longer would it just continue to do a slow leak? I fiddled with it some more today, but am leaving it again overnight and wont touch it until tomorrow night to see how far it goes.
Possum77 wrote: Flapper.
try Korky flapper.
Yup - It used to be a Korky flapper, and was replacing it again with another Korky flapper - Good to know its a recommended brand :)
kelaaa wrote: Another failure point is the flush valve seat. That is sealed with a gasket against the tank ceramic surface. On my tank style, it is tightened by tightening a large plastic nut underneath the tank while it is separated from the bowl. Keeping everything centered as you tighten the nut is a challenge. I suspect when bolting the tank to the bowl, this also relieves some of the compression applied by the nut. I can't believe people haven't invented a better system (for example access that nut from the inside of the tank rather than outside). The parts are cheap, but it is a huge pain to take everything apart.
I have a bad feeling it is the flush valve seat, which I was hoping for some way to confirm. Water is leaking INTO the bowl, so I know its either the flapper or the flush valve seat. I just got confused as after turning off the water inlet, leaving it overnight - The water leaked to just a bit above the flapper.

But yes I totally agree its a pain in the ass to have to take it all apart.

So bit of an update - I did one last test to see if it was the flapper or not.

-I cleaned the flush valve once more, ran my finger all around the rim to confirm it was nice and smooth to the touch and there was nothing slimy

-Turned off the water inlet

-Re-installed the "new Korky flapper"

-Grabbed a bucket of water and filled the water tank to where it usually fills to (I marked this before)

Using a wood paint stir stick (length of a ruler) that I had lying around I gently "pressed" down on the new flapper - I figured this would pretty much "guarantee" that the flapper is fully sealing if I was physically pushing on it (gently).

Stood there for about 5 minutes and watched the water drop fast initially then start to slow down.

So at this point I'm pretttttyyyyy sure its not the flapper. Maybe the flapper is leaking AND the flush valve at the same time? But if I am pressing down on the flapper and its STILL leaking into the toilet at a good pace - I'm pretty sure its the flush valve at this point.

I'm guessing once the water tank is full of water - Where ever its leaking probably has a lot of pressure on it and leaks fast - Then likely slows down as there is less water pushing down.

Anyways I digress, if the flush valve does some how have microscopic chips on the rim, or if the flush valve base is some how cracked or whatever - I dont think its going to matter how many flappers I try

So I will bite the bullet and try to change out the flush valve and the flapper all new at once - Right after I install a baby seat, put together the crib and dresser Face With Tears Of JoyFace With Tears Of JoyFace With Tears Of JoyFace With Tears Of JoyFace With Tears Of Joy
Deal Expert
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Sep 1, 2005
17944 posts
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Markham
chillychin wrote: Yup its a universal "Korky" flapper, picked it up at Home Depot :)

I was debating whether to go to Lowes and pick up another flapper to give it another shot - Maybe I have a defective one some how?



Yup! I turned off the water inlet and left the toilet overnight to see where the water level would drop to. It ended up stopping at maybe half an inch ABOVE the flapper. I thought it would either

1) Drop just below the flapper (implying its a flapper issue)
or
2) Tank would empty out, or at least be below the flapper line enough so I can see if its maybe the flush valve.

Again the odd thing was that the water seemed to stop JUST above the flapper - Not sure if I left it for longer would it just continue to do a slow leak? I fiddled with it some more today, but am leaving it again overnight and wont touch it until tomorrow night to see how far it goes.



Yup - It used to be a Korky flapper, and was replacing it again with another Korky flapper - Good to know its a recommended brand :)



I have a bad feeling it is the flush valve seat, which I was hoping for some way to confirm. Water is leaking INTO the bowl, so I know its either the flapper or the flush valve seat. I just got confused as after turning off the water inlet, leaving it overnight - The water leaked to just a bit above the flapper.

But yes I totally agree its a pain in the ass to have to take it all apart.

So bit of an update - I did one last test to see if it was the flapper or not.

-I cleaned the flush valve once more, ran my finger all around the rim to confirm it was nice and smooth to the touch and there was nothing slimy

-Turned off the water inlet

-Re-installed the "new Korky flapper"

-Grabbed a bucket of water and filled the water tank to where it usually fills to (I marked this before)

Using a wood paint stir stick (length of a ruler) that I had lying around I gently "pressed" down on the new flapper - I figured this would pretty much "guarantee" that the flapper is fully sealing if I was physically pushing on it (gently).

Stood there for about 5 minutes and watched the water drop fast initially then start to slow down.

So at this point I'm pretttttyyyyy sure its not the flapper. Maybe the flapper is leaking AND the flush valve at the same time? But if I am pressing down on the flapper and its STILL leaking into the toilet at a good pace - I'm pretty sure its the flush valve at this point.

I'm guessing once the water tank is full of water - Where ever its leaking probably has a lot of pressure on it and leaks fast - Then likely slows down as there is less water pushing down.

Anyways I digress, if the flush valve does some how have microscopic chips on the rim, or if the flush valve base is some how cracked or whatever - I dont think its going to matter how many flappers I try

So I will bite the bullet and try to change out the flush valve and the flapper all new at once - Right after I install a baby seat, put together the crib and dresser Face With Tears Of JoyFace With Tears Of JoyFace With Tears Of JoyFace With Tears Of JoyFace With Tears Of Joy
This is very frustrating...i know because i went thru it. I have two slightly used likely still good 3" flappers (i have a Toto toilet) and one be Toto flapper sitting in a box from my experience. I ended up replacing the entire flush towers and that fixed the problems.
Last edited by gr8dlr on Aug 26th, 2021 12:29 am, edited 1 time in total.
We're all bozos on the bus until we find a way to express ourselves...

Failure is always an option...just not the preferred one!
[OP]
Deal Addict
User avatar
Nov 23, 2010
1323 posts
577 upvotes
Toronto
kelaaa wrote: Another failure point is the flush valve seat. That is sealed with a gasket against the tank ceramic surface. On my tank style, it is tightened by tightening a large plastic nut underneath the tank while it is separated from the bowl. Keeping everything centered as you tighten the nut is a challenge. I suspect when bolting the tank to the bowl, this also relieves some of the compression applied by the nut. I can't believe people haven't invented a better system (for example access that nut from the inside of the tank rather than outside). The parts are cheap, but it is a huge pain to take everything apart.
Thats a good point - Any tips on how to keep it centered while screwing it on? Or any other tips?

Would it help if I had a second person just sorta hold it in place while I screw it on?
[OP]
Deal Addict
User avatar
Nov 23, 2010
1323 posts
577 upvotes
Toronto
gr8dlr wrote: This is very frustrating...i know because i went thru it. I have two slightly used likely still good 3" flappers (i have a Toto toilet) and one be Toto flapper sitting in a box from my experience. I ended up replacing the entire flush towers and that fixed the problems.
Yup! I am going to bite the bullet and just replace the whole damn thing

I havent done this before so just a tiny bit worried about doing it right without any leaks the first time around :)

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