How to install a new flush valve

If you have 2-part toilet, then tank is attached to bowl with 2 bolts.
Look inside tank and you can see bolts with rubber washers located on either side of flush valve.
The 2 bolts hold tank and bowl together and between tank and bowl is a washer called the spud washer.
So spud washer could be leaking ... or 2 bolts could be leaking.

1) If bolts are leaking, there is usually dripping all the time, and drips are visible on bottoms of bolts
If spud washer is leaking, then tank could leak only when tank is flushed.

2) First thing to try is tightening nuts on the 2 bolts. Nuts may be loose. Tighten nuts a few turns, and check if toilet still leaks.

3) To fix a spud washer, you usually need a new generic one from hardware store.
Newer tanks with 1.6 gallon flush have special sized spud washer.
Tank is upside down and spud washer is fit over flush valve

If you cannot find new spud washer, re-use old one and smear retorseal on it during re-assembly to make sure it seals. Rectoseal is good for many home plumbing repairs. More about that in a moment.


4) To take apart tank: Disconnect supply line to tank. Empty water out of tank. Remove nuts from bolts. Lift tank off. Wash out tank with hose. Make sure there is no sand or sediment left in bottom that might clog up flush holes located inside bowl after tank is re-assembled.

5) Remove old spud washer, and put new one on. Do a google-image search for 'spud washer' if you need more photos. New spud washer fits over flush valve. That's it. And then reassemble tank.
If you want to apply rectorseal to washer, put washer on as shown in photo above. Then smear-or-gawm rectorseal over area of washer that sits on bowl. Rectorseal will make sure there is no more leaking.

If you have a supply shut off to fixture shut it off and disconnect supply line from inlet to toilet . If your supply line to toilet is a flexible line then bend it so that you can direct water to small container. Slowly turn valve on to see what flow rate is at that point. If flow rate is not good then I would shut water off to house and replace valve. If flow rate to toliet is good I would reccomend you replace flush vallve. To do this shut off water supply to toilet. Disconnect supply nut to bottom of flush valve. There will be a retaining nut that holds flush valve in place in toilet tank. Remove flush valve after removing fill tube from flush valve to overflow tube. Replace with toto replacement valve or use Fluidmaster 400A. Instructions on box of 400A are easy to follow and if you have flex connector you won't need supply line washer. I would reccomend that before you install new valve that you put rubber gasket on shank of valve and slid it about halfway up the shaft. Make sure that inside of tank is dry and use a small bead of silicon caulking on top and bottom side of shaft gasket. slid gasket the rest of the way on valve shank,install in tank and put on retaing nut hand tight. Push down on top of valve and using channel lock pliers finish tightening nut securely.You may need to reach into tank and grasp valve body to stop it from turning. There are other things you can do if you have a working supply valve. Shut off valve and remove screws that hold top of valve in place and remove and clean surfaces. You can turn valve on slowly to help flush out any rust or mineral deposits. I hope this is of some help to you. Thanks

The rubber washer goes to the inside of the tank under the flush valve which gets screwed on with the large plastic nut on the bottom side of the tank. Then the foam gasket fits over the plastic nut which goes into the toilet bowl hole for the water to flow into the bowl. Tank needs to be removed from the toilet bowl.