Toto Drake leaking into bowl

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mike7

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I have a 2-year old Toto Drake (C744S) that's had a persistent problem with leaking into the bowl. I've noticed there are several threads here on similar problems, but after reading all of them I'm still at a loss on how to fix it.

The problem is a very slow leak, I *think* through the flapper. It's intermittent. My guess is that the flapper makes an incomplete seal after some flushes and seals properly after others, because the leaking happens maybe 1 flush out of 4. That is, if I flush and come back to the toilet, say, 20 minutes later, 3 times out of 4 the water level will be exactly at the fill line. The other 1/4 of the time it'll have leaked down about 1" below the fill line over 20-30 minutes. It's such a slow leak that it never even quite trips the fill valve; it'll just sit there at the 1"-down level with the fill valve open just enough to keep the water level constant at that point.

I thought I had this problem fixed about a year ago. After the plumber who installed it gave up on fixing it, I read everything I could find on it and tried a bunch of solutions. I replaced the flapper with a new one, sanded the nylon ring that the flapper falls onto to form its seal because there was a little roughness, cleaned everything thoroughly... nothing helped. What finally seemed to fix it was adjusting the chain length between the flapper and trip lever. The plumber had installed it really tight, with a bunch of slack links hanging over. I loosened it up by a couple of links and removed the extra links. That seemed to improve matters, and with a little experimentation I found a length that seemed to make it work reliably.

It had been working fine for a year, but over the past couple of months it's back to its old tricks. 1/4 flushes it'll leak slowly. I've gone back and cleaned everything and checked the chain length, but I can't seem to get it working again.

Any ideas? I've seen "silicone spray" mentioned here several times for this kind of problem, to spray on the flapper, but I don't know quite what that's referring to - is that just WD40, or something else?

Also, is there anything other than the flapper that could be leaking? It seems pretty clear that it is the flapper because of the way it leaks after some flushes but not others (the obvious thing that changes between flushes is the way the flapper is seated), but is there something else I'm missing that I should be checking?
 

Jadnashua

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Is the overflow hose attached with the provided clip, or stuck down the overflow tube? If it is stuck down the tube, attach it to the clip! or fabricate something to position it above the overflow and see if that makes any difference.
 

mike7

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Yes, the hose is properly clipped to the tube.

I'm pretty sure it's not a siphoning issue, if that's what you're getting at. The toilet fills after each flush exactly to the fill line marked on the overflow tube (about half an inch below the top of the tube) - there's no water running over the top of the tube or anything like that, and I don't see any water coming out of the hose after the tank has refilled after a flush. The level of water in the tank just s-l-o-w-l-y drops over time.
 

Krow

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Don't waste your time with sprays and greases .99% of the time, the symptoms that you are describing is your flapper. Replace your flapper and it should be as good as new
 

mike7

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Replacing the flapper was my first thought, too, and I've tried that - more than once.

Here's the bizarre thing: I actually have 3 other of basically the same Toto toilet that all work fine. I've swapped flappers between them, and the others keep working and this one keeps leaking.

So I'm pretty convinced it's not the flapper itself.
 
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Have you tried calling Toto? I would ask for a new flush valve.

Have you ever pulled the tank, checked the flush valve nut to make sure it is tight and even, that it doesn't have a damaged gasket, and that there are no surface irregulaties on the tank interfering with its tank to valve seal?

You've already been able to rule out the flapper, the fill tube, and the chain. That leaves only the flush valve itself. Someone once mentioned an alignment issue with the overflow tube that was causing trouble.
 
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mike7

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Thanks for the ideas. The flush valve sounds like the best bet for the next thing to try changing. Given that the problem is intermittent, it seems like it's got to be something that's perturbed on each flush, and the flush valve seems like the most likely thing after the flapper that fits that description.
 

caco3

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Commenting more than a decade later (2021-03-29) because (1) contemporary searches bring this one up as very relevant, and (2) I have a Toto Drake doing the same thing. I installed it in my house 10 years ago and it has worked well till now.

In my case I'm pretty sure it's not the flush valve* because when I shut off the water at the valve at the toilet inlet, the water level in the tank decreases gradually (roughly a gallon per hour), Also there is no water leakage evident outside the toilet at all.

I have replaced the flapper valve and also carefully checked the end surface of the 3 inch pipe end against which it mates. I'm pretty sure these are smooth, clean and sound. The toilet behaves the same with both flapper valves (the existing one, and a brand new replacement).

If the water isn't going past the flapper valve, and not leaking outside the toilet onto the floor (again, we're talking several liters per hour, so this would be very evident) I cannot help but suspect the seal between tank and bowl. I do remember about 20 years ago (in a previous house) hiring someone to install a 1.6 gallon per flush Drake and it did leak externally at the tank/bowl seal until I replaced it myself. So it's clear that seal can leak given imperfect installation.

I'm wondering if it can leak "internally" too. I know it seems odd for it to appear 10 years after installation, but I cannot think of any other explanation for the symptoms here. Does anyone have any experience about this?


* Edit: in hindsight it was the flush valve--as in Reach4's post below. I update this in subsequent posts here.
 
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Reach4

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In my case I'm pretty sure it's not the flush valve because when I shut off the water at the valve at the toilet inlet, the water level in the tank decreases gradually (roughly a gallon per hour),
You may mean it's not the fill valve.

The flush valve is that part which seals against the bottom of the tank, and has the flapper seat.

Leave that stop valve turned off at the wall off. See how far the water drops. Does it stop at the level of the flapper seat, or does it continue down to the bottom of the tank?
 

Sarg

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Just to mention a couple possibilities others have experienced.
The overflow tube on the flush valve may have a crack .............. and if it is the telescoping type they have an internal o-ring that may leak.
 

caco3

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Some progress: First I found the stop valve doesn't quite shut all the way off, so I had to replace that.

Now, with a reliable stop valve in, I see the level in the tank drops to a couple millimeters below where the flapper contacts the flush valve. So it seems the flush valve is indicated. Will source and replace. Thanks again all!
 

caco3

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Following up now. It was indeed the flush valve. The molded plastic body had a pinhole-like deteriorated spot about an inch up from the bottom of the overflow tube. This matched the level the water would leak down to and then stop. It was in a spot that was hard to see. I MIGHT have been able to see it with a mirror and good light source, but I was simply not thinking along those lines. My troubleshooting process had been focused on the seals and joints. Hopefully this will be useful for others like me.

Thanks again for the suggestions!


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