We've had a problem with sewer gases coming from the shower drain, and the toilet was installed incorrectly by the remodeling contractors. I re-installed the toilet correctly, and made a good seal to the flange now.

Now the toilet won't flush correctly, with the water just swirling down instead of a good flush. And when I was working on it, after running water in the shower to ensure the trap was full, someone upstairs flushed the toilet, and I heard the water drain out of the shower trap with a nice loud gurgle!

Months before the remodel, we had a backup in the drain between the shower and the main line. Apparently, the drain from upstairs goes past the shower on its way to the main drain. A large backup ensued through the shower stall drain.

Is the vent clogged?

Thanks!

Gil H.