On many Kohler toilets and some American Standard toilets, rather than a traditional flapper valve controlling the water flow from the tank down into the bowl, you will instead find a tower or canister-style flush valve—a large round cylinder—mounted over the flush valve opening. Tower-style flush valves have a round rubber gasket instead of a flapper to keep water in the tank, and during the flush, the entire tower/canister lifts upward to release water down through the tank opening. The flush valve seal at the bottom of the tower/canister can and will go bad eventually, just like any other toilet flapper, due to age, hard water, tank chemicals, being allowed to dry out (no water usage), or a combination of any of these. Other times, the seal may bend in at the bottom, preventing a good seal and resulting in a running toilet.
Another reason to change the seal is when it becomes hard to flush the toilet. An old, stiff flush valve seal can put extra stress on the handle or chain. If you notice that the toilet is getting harder to flush, it may help to change the flush valve seal before something breaks.
Fortunately, a tower flush valve seal is very easy to replace, though the process looks a bit different than replacing a standard flapper. But you can complete the repair in just a few minutes, and all you will need is a new seal to match your tower/canister flush valve.
How to Replace a Bad Seal on a Tower/Canister-Style Flush Valve
- Shut off the water to the toilet by closing the shut-off valve under the toilet. If your toilet doesn't have a fixture shut-off valve (rare, but sometimes the case), you will need to shut off the water at the main water supply shut-off valve to the home.
- Flush the toilet and check to make sure that the tank doesn't begin to refill with water. (If the fixture shut-off valve is old, it may fail to fully stop the flow of water.) Hold down the flush handle to empty as much water from the tank as possible.
- Remove the refill tube that leads into the top of the overflow pipe on the tower. Some tower flush valves do not have this but the Kohler models do. The refill tube needs to be removed before you can get the seal off of the tower. To do so, just pull the fill tube out of its housing or remove the clip (if it has one), then pull the tube out of its fitting.
- To remove the old flush valve seal, lift up the tower away from the flush valve opening, then grip the sides of the rubber seal and pull it out of the groove that it fits in. Work the valve seal up and out of the groove all the way around the tower. Keep the seal moving up the tower a little at a time until it is all the way off. Note: if you have trouble doing this while the tower is in the tank, it is an easy matter to disconnect the lift chain and lift the entire tower off the flush valve assembly in order to remove the seal more easily.
- Install the new flush valve seal by positioning it around the top of the tower and slowly slide it down toward the seal groove at the bottom. Pull one side of the seal into the groove and hold it in place with one hand while working the rest of the sides into place until it fits evenly on the tower all the way around. Check to make sure that the seal is completely in the groove.
- Reinstall the refill tube in the same manner as it was originally positioned. If you didn’t need to remove a clip to remove it, just push the tube back snugly into its hole. Otherwise, position the clip in its original position.
- Turn the water supply back on. Wait for the toilet tank to fill completely then check to make sure that the toilet flushes correctly. Make sure that the new flush valve seal sits snugly on the tank opening. You can often hear if the seal is leaking, which can occur if the flush valve seal is not positioned evenly in the groove all around the tower.
- Flush the toilet several times and watch for any problems before putting the tank lid back on.