Problem with toilet (vent problem?)
 

Since we moved into our house 8 years ago, we have had problems with a downstairs toilet. The toilet ran slow, and would occasionally clog. I thought it was a toilet problem, so I replaced it a couple of years ago. The new toilet never seems to empty fully -- the last bit of liquid "chugs" out of the toilet.

About every 7th flush or so, the flush gets super sluggish, and I also hear gurgling in the tub. That's usually a sign that the next flush will completely back up. Then, when I plunge the toilet to remove the backup, I hear gurgling in the tub AND the sink. If I don't plunge it, and leave it for a few days without activity, it works okay again.

I've had most of the waste line replaced, but that didn't help the problem.

So -- do I have some sort of venting problem? The other downstairs toilet and the upstairs toilets work fine.

Thanks in advance for any help you can offer.

some codes say you do not even have to vent a toilet.but at the same time if none of the fixtures are vented or clogged that could create the gurgling sound and issue. depending on how fixtures were plumb you can try this to confirm it is a vent issue remove trap from sink then proceed with the flush ritual that creates problem if that fixes it you know it is not venting. i would then say it is a vent issue and then add an aav "air admittance valve aka cheater vent" under sink or try to see if it has a vent and where it is clogged at

I removed the trap from the sink. The toilet is still backing up -- no difference. So, you're saying I do have a vent problem, or I don't?

less likely after issue starts does the sink and tub drain slow if turned on

No, they both drain fine.

can you take a picture of pipes in basement maybe or bathroom to see lay out of fixtures. i still am leaning towards a blockage then a vent issue but some one else may have other suggestion

Have you ever had the drain snaked?

Yes, a couple of times. It made no difference.

what kind of snake used i small one or large on where toilet has to be removed

Large -- the toilet was removed. The plumber who did it said he didn't encounter any blockage.

Have you ever had a camera run down the line?

Never had that done.

So, it seems that neither you nor Jay believe this is a vent problem -- correct?

so what did he suggest

It's not that I don't believe it's a vent problem it's just I have seen more with restrictions in the line than I have seen with venting with toilets.

What brand toilet paper do you use?

Angel Soft.

So, what would explain the very predictable behavior of the flushes (7 or so flushes that don't seem to clear very well, followed by gurgling in the tub, then I plunge it, hearing gurgling in the tub and sink, then the line clears for the next 7 flushes)? I guess you're saying there's something in the line that keeps blocking the flow?