I have run into a real head scratcher. I live in a 1 bath rambler, built in mid 50s, with well and septic. Was downstairs y-day and saw drip from underside of toilet, so decided to pop it off and replace the wax seal. Note no problems with the system have been experienced–I pump my tank once a year, and everything was working fine.
Replaced the seal, and I had it all back together. Went to hit the lever and tank drained into bowl fine, but bowl wouldn’t syphon,it just filled high, like plugged, then slowly drained back.
Long story short, I have had it off and on 4 times, completely flushed everything, etc. Every so often it would flush as it is supposed to, but more often than not it wouldnt.
Started to suspect a possible vent issue when I saw toilet bubble when tub and sink in bath ran at same time. The tub drains downstream of the toilet, and first has to come up into what appears to be an iron cup with a lid. From there it drains into main pipe. I removed lid from this cup, toilet flushes fine, lid back on, it flushes slow. Lid has to be on or else the toilet or tub flow comes up in the cup, and will o-flow it.
Any ideas why this has occurred, and possible solution? Thanks.