If I flush the American Standard Champion 4 toilet and wait for it to fill & water to stop running, then it flushes fine. After it fills, the level in the bowl always starts to fall. It never gurgles. After a few minutes, it has maybe 1/2 or 2/3 the water left in the bowl. No water visible on the floor and the tank level doesn’t change. Then it won’t flush well. The water level in the tank doesn’t change. I used a plunger, toilet snake, used a 25 ft snake on the shower and sink in the bathroom. This did help sink to drain better, didn’t help toilet. I snaked the vent from the roof, re-seated the toilet with a new wax ring. Replaced the toilet valve, flapper, etc. Still the same. I might call plumber, or maybe just replace the toilet.
We have reviewed your request and we understand what you are describing and it seems to lead us to two possibilities:
- Either you have a possible bad casting in the water closet bowl which is allowing the water to leak out through cracks in the porcelain on the interior.
- A rag or something that wicks water could be caught in the trap way of the bowl that you can not see but it basically transfers water out of the bowl and down the drain.
These are possibilities based on the description of the issue and would be easier to diagnose with an experienced plumber looking at the toilet.