A toilet tank replacement is needed if there is a rough spot on the rim where the flapper sits. The toilet flapper seal is broken if so the toilet leaks inside the tank from this flapper leak, but no water is visible.
The mechanism in a toilet that holds and releases water in called the flush valve. Old timers called them a Douglas. It is important that there is a good seal between the stopper and the flush valve so water does not leak out of the tank.
The flush valve is one of the most dependable parts in a toilet, and many people replace everything in the toilet before they realize the problem is from the flush valve.
What will it take to replace the flush valve?
1. Large slotted screwdriver.
2. Adjustable wrench or set of open-end wrenches.
3. Large Channelocks.
5. Optional tool, a Dremel with a cutoff wheel.
The steps are as follows:
Shut off the water. Flush the toilet while holding the handle up to drain all the water out of the tank. Sponge all remaining water out of the tank.
Remove the water supply line from the toilet only, not the wall.
With the large screwdriver holding the screws in the tank, use the wrench to remove the nuts below the tank. Toilets may have two bolts, three, and even four holding the tank to the bowl.
Gently wiggle the tank and loosen the foam seal between the tank and the bowl. Take the tank off for the next step. Put a towel or rug on a workbench or kitchen table to prevent damaging the tank.
Underneath the tank to bowl washer is the flush valve nut. Remove it with Channelocks if possible. We find about half are frozen and we use the Dremel with the cutoff disk to cut through the large nut. Cut at a slight angle most of the way through the nut. Twisting in the cut with a screwdriver can split the nut. Once the nut is removed, clean the hole before installing the new flush valve. Do not be a sissy when tightening the nut on the new flush valve.
Install a new tank to bowl washer, they are spongy, and replace the washers on the tank to bowl bolts. Only use one rubber washer under the head of each bolt in the tank. Metal washers in the tank will cause a leak.
Reattach the water supply line and you should be done.