Plumbing in the Home/Leaking Gasket
Our American Standard toilet has been running, so I took off the tank lid and it looks like a gasket inside is disintegrating. I took a picture of it, and I was wondering if you could tell me if it is called a flush valve seal, or something else. It is the black seal under the red flapper: http://i.imgur.com/GTi2HRN.jpg
You are correct. It is a flush valve seal. It is actually a double seal the larger ,spongier one seals the tank to the bowl on the outside and the flat or slightly beveled shaped one seals the flush valve to the tank on the inside. Old timers call them spud gaskets as well. (The spud gasket is actually the outside tank to bowl gasket only but commonly referred to as the spud.) You can get a replacement at most plumbing supply houses or online at American Standard.