toilet running - newish flapper!

About 2 years ago exactly I replaced the flush valve with a kit that included a new flapper, which I did put in at that time. About 3 months ago the toilet started running periodically to fill the tank. All signs pointed to a bad flapper (die test showed a leaky flapper). The company (Fluidmaster) mailed me a new replacement flapper under their warranty program, so I replaced it again then. Now every now and then I hear the toilet tank filling again, not as often as before, but still my impression is that it should never need to do this unless there has been a flush.

It's only been 3 months on the new flapper, so I'm not inclined to think that is the problem. But could it be anything else? Thanks for any ideas you might have.

 

Could be seal between tank and bowl leaking. Will do same as leaking flapper.

 

Check the fill tube that goes from the fluid master to the overflow tube. It should be on a bracket that stilts the fill tube above the overflow. If you just sent the fill tube down the overflow without the clip, it can siphon water out of the tank and cause phantom flushing. Also, make sure the chain going to your flapper does not have too much slack in it as that can create a situation where the chain gets sucked into the flush hole and prevents a good seal.

 

When I replace a flapper, I run my finger around the mating surface on the flush valve to check for imperfections, then I check it with dye. Sometimes I have to try 2 or 3 before I get a good seal.

A flapper from the toilet manufacturer usually has a slightly better chance of success than generic flappers.

 

Thank you, everyone! I will check all of these things. steve_gro, when you say imperfections, do you mean just dirt or the sort of thing that can be wiped away? If you mean some other kind of more permanent imperfection, how do you get a good seal? pugsl, the seal between the tank and bowl can be tightened further, right? I think I remember there was a big nut holding it on.

 

And make sure the tank level isn't set so high that it's overflowing, dribbling down the pipe slowly... making it run to refill.

 

Imperfections could be dirt of debris that can be wiped away or small divots that you might be able to sand. Anything that prevents a good seal. If there are imperfections that can't be fixed, you replace the flush valve.

 

Yes tightening the nut might help but if you are that far I would just replace it. No sense doing twice.