Richard Ledford
New Member
I have a Niza PRO toilet using a Fluidmaster Model 640 hard plastic flapper. The unit had gradually begun cycling continuously where it would fill and stop, but then a certain amount of time later a brief refilling cycle would initiate, indicating a slow leak. As this issue worsened, I began to hear a slight gurgling after tank stopped filling and the resume filling was coming a lot faster.
Inspecting the flapper seat and seal, I felt a large bump on the bottom side face of the silicone seal. Removing it, I saw there were other other bumps of a medium and small size, and they all looked like blisters, but which I assumed were fabrication defects, but if that were true, how could the flapper have worked fine for a couple years?
This got me curious whether other people were having a similar problem. Obviously, I could replace the silicone seal to fix the flapper leaking problem, but I wanted to know more as to what caused this. With some Google searching, I learned that indeed it was water that was penetrating into the thickness of the silicone layer of the seal to a sufficient level that the silicone would gradually bulge out to form a water blister.
Logically, it seemed to me that the downward water pressure on the flapper pinching against the silicone seal's ring of contact with the seat should have enough force to squeeze the water back out via the same path of whatever way it arrived at the blister zone, but that was obviously not the case. So instead of dropping $4-6 on a new silicone seal, I decided to try the Googled suggestions of just popping the blisters.
My initial thought was that poking a hole would release the water, but then leave a silicone surface imperfection that might allow a new path for leaking to occur. I decided to use a 6" cast iron C-clamp to see if I could just squeeze the seal tightly enough to force the water back out along the same path from which it had arrived. When I did this, I observed that instead of the water exiting from the seal, it just shifted away from the clamp squeeze zone and formed a new blister protruding at the edge of the seal, now visible in the gap between the clamp jaw and the screw tip.
I decided to poke this relocated edge blister to drain the water at a spot where it would not mar the sealing face of the silicone, and this did leave a nice smooth & flat surface where the prior blister bump had been. I proceeded to do this for the five remaining blisters only to discover that some of them were interconnected, causing water to travel between them as I C-clamped against the seal faces. This prevented movement of the blister out to the edge of seal, since water just moved to the adjacent blisters that weren't being squeezed.
By placing the square shank of a 5/8" chisel (side of knife would work too) against the C-clamp's screw tip, to give a larger contact area with the seal face, I was able to squeeze down on all three of the interconnected blisters simultaneously, and this pushed the water out to the edge where it could be poked and drained. After popping all of the blisters was completed, the the seal face looked very flat and smooth, with no poke holes present to possibly give any new leak paths.
I am still not clear what drives the water into the seal to form the blisters in the first place, and by what path does it arrive there. It may turn out that the holes I poked into the outer edge of the seal will now provide an even more accelerated way for water to flow back into the silicone and refill the blisters to trigger resumed flapper leaking. I will follow up on the long term result of this attempted fix.
Clearly this a manufacturer responsible flapper quality control issue, resulting from a silicone seal material fabrication defect. A 100% dense silicone material should not allow any water to penetrate into it at the very low pressures that a toilet tanks height of water in the full tank can produce (less than 1 lb.)
-RRLedford
Inspecting the flapper seat and seal, I felt a large bump on the bottom side face of the silicone seal. Removing it, I saw there were other other bumps of a medium and small size, and they all looked like blisters, but which I assumed were fabrication defects, but if that were true, how could the flapper have worked fine for a couple years?
This got me curious whether other people were having a similar problem. Obviously, I could replace the silicone seal to fix the flapper leaking problem, but I wanted to know more as to what caused this. With some Google searching, I learned that indeed it was water that was penetrating into the thickness of the silicone layer of the seal to a sufficient level that the silicone would gradually bulge out to form a water blister.
Logically, it seemed to me that the downward water pressure on the flapper pinching against the silicone seal's ring of contact with the seat should have enough force to squeeze the water back out via the same path of whatever way it arrived at the blister zone, but that was obviously not the case. So instead of dropping $4-6 on a new silicone seal, I decided to try the Googled suggestions of just popping the blisters.
My initial thought was that poking a hole would release the water, but then leave a silicone surface imperfection that might allow a new path for leaking to occur. I decided to use a 6" cast iron C-clamp to see if I could just squeeze the seal tightly enough to force the water back out along the same path from which it had arrived. When I did this, I observed that instead of the water exiting from the seal, it just shifted away from the clamp squeeze zone and formed a new blister protruding at the edge of the seal, now visible in the gap between the clamp jaw and the screw tip.
I decided to poke this relocated edge blister to drain the water at a spot where it would not mar the sealing face of the silicone, and this did leave a nice smooth & flat surface where the prior blister bump had been. I proceeded to do this for the five remaining blisters only to discover that some of them were interconnected, causing water to travel between them as I C-clamped against the seal faces. This prevented movement of the blister out to the edge of seal, since water just moved to the adjacent blisters that weren't being squeezed.
By placing the square shank of a 5/8" chisel (side of knife would work too) against the C-clamp's screw tip, to give a larger contact area with the seal face, I was able to squeeze down on all three of the interconnected blisters simultaneously, and this pushed the water out to the edge where it could be poked and drained. After popping all of the blisters was completed, the the seal face looked very flat and smooth, with no poke holes present to possibly give any new leak paths.
I am still not clear what drives the water into the seal to form the blisters in the first place, and by what path does it arrive there. It may turn out that the holes I poked into the outer edge of the seal will now provide an even more accelerated way for water to flow back into the silicone and refill the blisters to trigger resumed flapper leaking. I will follow up on the long term result of this attempted fix.
Clearly this a manufacturer responsible flapper quality control issue, resulting from a silicone seal material fabrication defect. A 100% dense silicone material should not allow any water to penetrate into it at the very low pressures that a toilet tanks height of water in the full tank can produce (less than 1 lb.)
-RRLedford
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