Another toilet running

[caro]

My vintage American Standard circa 1940s one piece toilet keeps running intermittently. I've changed the flush valve kits twice, trying different model numbers. Latest replacement was yesterday, installing a 47086-0700, which, according to American Standard, is the correct flush valve for this toilet. There can be longer periods of no running, then periods of running every 10 or 15 minutes. I usually turn off the shutoff valve to keep it from running. When water is off, I sometimes hear a click, indicating a trigger to run water. I don't know enough about plumbing to know what to try next. Someone suggested there could be a hairline crack?
This running problem began a few months after replacing the original flush valve. It has been running for a year. Any help would be appreciated!

 

[Reach4]

Float valve? Open the tank. See if the stopper is hung up. Gently wiggle. See what the minimum action that you can take is to get the water stopped from going down into the bowl. That can maybe give a clue as to what might cure this.

A photo of the inside of the tank could give good info.

 

[Sponsor]

 

[caro]

Can you take a picture of the inside of the tank for us?

 

[caro]

brand new brass flapper seat. It is smooth with no pits.

 

[Reach4]

I was expecting to see an old-time stopper.

It is hard to tell from that angle, but if your chain is tight, maybe loosening it by a few beads.

Fluidmaster Leak Sentry https://www.fluidmaster.com/products/toilet/fill-valves/400lsr-universal-fill-valve-leak-sentry/ or Korky Waterwise https://www.korky.com/products/fill-valve-replacements/waterwise-fill-valve could save water when the occasional hang-up occurs.

 

[Terry]

The fill tube from the fill valve may be too far down the overflow. That can siphon the tank and cause it to constantly refill. I would rig something that daylighted the end of the black tubing so that there was an air gap between the end of the hose and the top of the overflow.

 

[WJcandee]

Siphoning from a refill hose stuck too far down is no joke. I would try rectifying that before anything else. If you're not handy enough to rig something yourself, you can google "Model 599 Fill Tube and Clamp" and find places that sell it. That's the item shown in the furthest-right drawing in Terry's post above, and is pretty-nifty for that kind of installation. Then you make sure that there is space between the hose and the overflow, and no siphon will be possible.

 

[caro]

Thanks, everyone! I'm sending them thread to my handyman extraordinaire.

 

[caro]

The fill tube from the fill valve may be too far down the overflow. That can siphon the tank and cause it to constantly refill. I would rig something that daylighted the end of the black tubing so that there was an air gap between the end of the hose and the top of the overflow.

This fixed the problem! The fill tube was too far down. I ordered a fluidmaster refill tube and clamp and no more running toilet.
Thank you so much. What a great experience to put out a question that I've been struggling with and get it answered!!!