The flush valve on a toilet is the mechanism that fits over the siphon hole in the tank and prevents water from draining out until you activate it by pushing the flush handle. In most toilets, the working part of the valve is a rubber flapper, but don't be surprised if you open your toilet tank and find a sealed canister instead -- that's the type your toilet has if you have a dual-flush control, and they are becoming common on single-flush toilets, too.
Don't be dismayed if you find one, since they are just as easy to repair as flapper valves.
Troubleshooting a Flush Valve
The principle of operation of a flush valve is uncomplicated, and diagnosing problems is usually straightforward.
* **Running Toilet:** The most common symptom of a flush valve malfunction is a running toilet -- one that fills continuously or cycles on and off when you aren't using it. This is caused by a poor seal, which may be the fault of a worn flapper or canister gasket or that of mineral deposits collecting on the valve outlet
* **Flush Lever Doesn't Work:** If you push the flush lever or button and nothing happens, the problem is usually related to the chain or -- on some canister valves -- the rod that connects the valve to the flush button.
More often than not, the chain has become disconnected and needs to be reattached
* **Toilet Won't Stop Flushing:** If your toilet has a flapper, this is another chain-related problem; the chain is too short. If your toilet has a canister, the valve inside the canister is sticking in the open position
* **Incomplete Toilet Flush:** As far as flapper valves are concerned, incomplete flushes are also usually related to the chain; in this case, the chain is too long, and the flapper isn't lifting high enough for water pressure to keep it up.
This isn't a common problem with canister valves
Repairing a Flapper Valve
- Turn off the water supply valve and flush the toilet to drain the tank.
- Disconnect the chain from the flush handle by lifting the hook. Remove the flapper either by pulling the ears off the posts on the overflow tube or lifting it up and off the tube.
- Scrape or sand off any mineral deposits you see on the valve opening that could be preventing the flapper from seating properly
- Take the flapper to the hardware store to find a suitable replacement. Many toilets accept a universal flapper, but some require a specific type.
- Replace the flapper by reversing the procedure for removing it. Reconnect the chain to the flush handle, making it long enough to lift the flapper between 45 and 60 degrees when you push the handle. Tun on the water and do a test flush, then adjust the chain length, if necessary.
Replacing the Gasket on a Canister
Replacing the Flush Valve
Replace the bolts holding the tank to the bowl as well as the sponge gasket on which the tank rests when you replace the flush valve.