when i flush toilet it continues to flow from the cistern while the cistern is filling up again. i have replaced old siphon with new one and still the same problem arises. to stop it i have to lift up ball c*ck until cistern is empty and then it is ok. What is wrong?.
Look closely at the flapper valve. Thats where the water exits to the bowl, it lifted by a chain from the flush lever.
It should fall back into place when the lever is released and water flow under the valve drops as the cistern empties.
The seat may be dirty, preventing a proper seal, or the chain may be twisted stopping it from closing properly.
Replacing it isnt a big job and they arent very expensive.
Another very obscure possibility is that the water is rushing in so fast it won't allow the flapper to drop. Try just barely opening the service valve and see if that makes a difference. If so, you're done.
I don't know what the innards of your wc are like, but a couple of years ago I replaced an old float ball/arm fill valve in one of our toilets with a "Fluidmaster" fill valve and had the same kind of problem.
The bowl refilling flow through that small tube stuck into the top of the overflow tube was so strong it splashed back up when it hit bottom it actually "blew" the flap valve open enough so it wouldn't seal.
I called fluidmaster about that and they said it was a well known problem and that they'd pop a "refill tube restrictor" in the mail to me, gratis.
I didn't want to wait, so I fixed the problem by sliding a couple of three inch long pieces of wire solder inside the refill tubing, which cut the flow down ebough to eliminate the problem. They're still in there and as far as I can tell there's more than enough refill water supplied to fill the bowl as high as it will go.
Maybe you've got a like situation?
Jeff
I always hang that refill tube on the outside of the stand pipe anyway. They usually don't need it for bowl refill.
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