commode occasionally runs already replaced flapper still doing it

You mean you have to shut off whole house water supply? Don't have a water c*ck right under the tank just to shut off water going to tank?what kinda plumbing is that?

Just use your dye to keep it simple. But if it's the valve you should see the water rise to the overflow tube. The overflow tube shouldn't submerge. There's also a possibility your overflow tube seal is leaking through or the tube itself has a crack that allows water to leak down.

Ameeen

I have a toilet that runs like that (small tank-to-bowl leak). I've tried that, after replacing the fill valve, flapper, and flapper seat more than once. No effect on the leak & running (except when I made it worse for awhile, flapper chain a little too short). The food coloring test doesn't help (it shows in the bowl, but I already know it leaks). It diffuses too thoroughly to show the location of the leak.

????

A valve that hasn't been turned in years is likely to get stuck and be no better than no valve at all. It could be worse. It could leak on the floor.

With mine, I think the only thing left it can be is the flush valve. I replaced it once already about 5 years ago. There was originally a brass one in place and it was a bear to remove as the brass nut almost seemed like it fused to the tank, but I managed to free the assembly. Replacement was with Fluidmaster plastic. Now in my head I'm trying to decide if I want to again go with Fluidmaster or opt for the brass as I see brass is still available. The brass that had originally been in there must have lasted 25 years.

Peeeeaceeee beeee unto you.

I'll admit, I fail to exercise my various shut off valves around the home. Likely to be a problem when they are needed.

Rading your "no better than no valve at all" reminds me of the old limerick about differnt sizes. How about a rewite?

There was an old man from alt home repair Whose valve was not turned, I declare One was rotted and small T'was no valve at all The other won several prizes.

Does the tank have over flow tube? Is the water level below the top of the tube?

I'd choose brass over other metal, even if it costs a bit more. The savings is over time, and having a dependable toilet.

Yes and yes.

I just ordered the brass flush valve with ball and rods. Hopefully take care of this leak.

The only question remaining is that I'm wondering if I can coat the brass parts with something to keep them from seizing up either against the valve itself or against the porcelain commode. When I had to remove the prior brass parts, I actually had to dremel them away to get them freed from the commode. Just trying to avoid that next time.