Or it's called an air admittance valve and they should sell them at the hardware Home Depot or Lowe's you may be able to do with yourself if you're a little bit handy..... is there a bathroom above that you flush the toilet and then you hear gurgling in the downstairs toilet or sink... if that's the case yeah they didn't invent it correctly they can't tie the lower bathroom toilet directly on the line they have to go up to a side Vince and then over to this stack pipe.. if it's always done it since you moved in it's a vent problem if it's just something that's happened recently then it's a drain problem I've been doing Service Plumbing for 30 some years

Maybe try a natural drain cleaner conditioner that are based on enzymes and microbes. Chemical ones just like a hole in the gunk where the natural ones keep working to clear the whole pipe. Another plumbing trick is Dawn dish detergent and near boiling water, that can clear fats.
Terms to search w drain cleaner
natural
Hair or he is clog
Fat
Sewer main
Deep

I don't wish to post retail products I just randomly search. Also don't use enzymes with septic systems if you can help it they can clog your outer leach field.

But I know that at one point my now-ex-husband would get up on the roof and pour a bottle of the industrial strength drain cleaner down the pipe.

https://www.repipeyourhouse.com/how-to-unclog-a-vent-pipe/

I just posted this for the info about your issue, but I'm stunned by that company's prices. I paid $88 for a service call from my usual drain cleaner guy, but I pretty much decided that I'm not going to use him anymore. I had a huge issue at a rental and a company came and tried hydro jetting. They charged $250 an hour, but it blows out everything in the line. It didn't work in that case, because it turned out that the power company had put a new pole right on top of my sewer line, so they fixed it. But I think I'll try the hydro jetting whenever another issue comes up because I think it'll last a lot longer. A snake just cleans out a tiny tunnel, but that hydro jet cleans the line completely. Worth it, IMO.

A lot of times a jet something that they could snakes just so they can charge you more I know I've been doing this a long time

I have had to call the guy about once a year at my daughter's house, and I'm going to give hydro jetting a try and see if it lasts longer.

I agree that you might just be able to snake in a lot of cases, but I don't think you should have to call a drain cleaner company every year. Shortly after we bought the house I live in, our sewer line had a break. It took awhile, and a lot of work, but we replaced it ourselves and haven't had a single issue in close to 18 years. It makes sense to me that blowing out the line completely is the way to go.

Even if the line at my daughter's house can go an extra year between service calls, it's worth it to me, just for the sake of convenience.

I started out at Roto-Rooter in the late 80s and they used to have to guarantee their lines for a year so they taught the guys well on how to make drains and what blade to use nowadays they don't really teach because there's not as much money and sneaking the lines as there is no digging them up or jetting and camera them

I had him go snake the line, and he called and said he couldn't get through because there was a break in the line. He recommended another company to run their camera to see where the break was, so I called them. They marked on the ground where the line went, which they determined with their camera. Just a few feet beyond where the marking ended was the power pole. Any idiot could see that's what happened, and I can't believe they didn't put the pieces together and conclude that whoever put in the new pole put it on top of my line. They gave me estimates for replacing the line, and then were sort of rude when I let them know I was going to get some more estimates.

So I called another company for their estimate, which they gave me. I was pretty sick about how much I thought it was going to cost me.....anywhere from around $10,000 to over $25,000. While I was thinking about how I was going to proceed, the guy from that company called and told me about hydro jetting. I thought it was worth a gamble of $250 to possibly save tens of thousands of dollars.

One of my sons is an engineer for one of the top construction companies in North America, and is familiar with hydro jetting. He lives about two hours away and came down to observe and advise, and he's the one who figured out what happened with the power pole. Within a few hours a subcontractor for the power company had fixed the situation.

I never thought I had a reason to question the guy we had always hired to clean sewer lines, but based on the fact that he recommended a company that I believe didn't have a clue about what they were doing, I'm done hiring him. So I guess the moral of the story is to be very careful about making recommendations to customers about other companies. I'm pretty suspicious that they knew the power pole was on my line, because it was so obvious, but if I had hired them to put in a new line, they'd have still made their money before letting me know what the problem was.

Incidentally, the contractor who did put in the new line, courtesy of the power company, told me it happens more than people think that poles get put on top of sewer lines. It's sort of funny that the "Call Before You Dig" company would do that.

my electric leaf blower directly to the drain pipe about a year ago. Just wrapped a towel around the end as a gasket, it was a good fit. Helped a little.

A lot of times gurgling is a sign of backed up main drain line. The lower fixtures usually show signs first.

If it was a main vent problem you might notice it upstairs too. My buddy’s condo had a clogged roof vent and his downstairs neighbor flushing her toilet caused his shower trap to gurgle - even to the point it sucked his trap try.


Or it could be as you suspect. It could be a local obstruction in the vent that joins the main stack above and behind your sink. If one exists. But that seems less likely.


The sink may not be vented at all - just relying on the diameter of the pipe to allow free flow. If the pipe is partially obstructed this could cause a gurgle.

You could try an under sink air admittance valve vent that come attached to the trap. About $20-30 bucks on Amazon. Though they don’t meet code in many jurisdictions, they can be a solution for unvented fixtures (in islands or basements etc.).

My bet is main line obstruction. Are you on a basement or a slab?

😁

It is a basement. There is a square end plug in the plastic pipe, so I guess that's useful.

Because of the install, as I understand it and from the little they told me on install, there is no main stack above and behind the sink. The main stack I think is the toilet drain pipe, which is where they tapped off to make the roof vent. I think the upstairs tub drains into that drain pipe as well, because I can hear the water draining through the toilet drain pipe in the closet wall.

But now that you mention it .... the flushing. They flush fine, but it's not the robust drop there was decades ago, and both were subject to an occasional light clog, the upper for who knows why, the lower because the pipe made two twists below.

So the two symptoms, one sink gurgle and not too robust flushing, do seem to add up.

How about the flange I think they call it - at the septic tank? The inflow hits a vertical wall to force solids to sink. There is a cleanout above. That hasn't been opened in wow ... 25-30 years. And it's a direct straight line backwards up the drain pipe. I wonder if there are tree roots involved. Guess I'd better remove the cleanout plug and see if anything's going on.

Thanks HBS

up the horizontal pipe. There were no obstructions, but water flowed a little better afterwards. The main line is only about 17-18', so I got pretty far up there. And - and - on the other end of this horizontal almost straight pipe which accepts all the drainage pipe in the house, is the plastic cleanout valve! So if I have to open that up it's easy.

However the bath sink still gurgles slightly, but one set of burps, not two. So I will treat this with a little washing soda last thing each night and see where it gets to. Washing soda cleared the kitched trap in one overnight application. If washing soda doesn't work, there is still opening the cleanout, as well as snake the drain pipe again.

Thanks to all for the ideas. Hope the progress so far isn't temporary.

You don’t want any surprises if it’s full. Lol.

They sell attachments for pressure washers that spin and self feed. Kind of a poor man’s water jet blasting.

You could rent a drain cleaning machine from Home Depot but that’s a two person job. Easier if you go at it from outside so you don’t have to move the heavy machine downstairs - plus no mess inside. Better to get the auto feeding machine.

The upstairs and lower bath sinks are directly above one another. They are furthest removed from the toilet drain line. The tub drains are separate. So the only air these 2 sinks pull is from their own drains. The upstairs doesn't gurgle. The downstairs has the noise after draining out. Part is from the full trap, and it sounds like part is in the wall, higher than the sink. They wouldn't put a trap in the wall, there's already a p-trap at the upstairs sink. So I'm still suspecting a partial clog in the lowest part of the lower sink drain. Have to snake again.

Or maybe it's just the sinks are unvented. I saw a This Old House video, mentions a "cyclone" when the sink is full. Yeah, that's what I get in the downstairs sink. But the cyclone action seems to open up the drain some. It drains better after a cyclone, and even better if the water is just about boiling. Then in a few days it's back to the same old noises.

Thanks!

As you correctly noted, the plumbing vent pipe should be venting the drain line upward through the roof. There are several common reasons for the gurgling noise you are experiencing. First, the vent pipe may be too short, or it may have been installed at an angle which is causing the pipe to fill up with water. Next, if the vent line is too low inside the pipe and water flows down the pipe, it can cause an overflow at the sink as it tries to pull the air out of the system. Finally, if you have a vent stack that is too small in diameter, it will cause the vibration you are hearing.

To my memory, it didn't work this way when new. It acts like it's not getting enough air. Yet the condition will improve slightly after mass flushing of hot water. As noted, the roof vent is only from the top of the system, there is no roof to basement dedicated vent.

I'm going with a minor clog in the drain pipe, the roof vent pipe, or one of these air-bleed valves in the wall malfunctioning (but it was built in the mid-70s, did they have air-bleed valves back then?

It does have a full S trap on this sink. I'm thinking first step is a P trap replacement.

The drop in the toilets is nothing to write home about either.

Nothing came up with the snake, it was clean as could be. The water flows slightly better, but still a few quick gurgles and then a slight pause and a gulp. It is silent if the volume of water is below about 12 ounces, and if the sink is full it gives massive gurgles and a gulp at the end.

I also cleaned the tub drain. 40 years of clog. Took the whole stopper assembly out. There was a massive hair ball that had become sediient at the bottom, so it had poor flow. Now flow is easily twice what it was.

https://www.homedepot.com/p/Oatey-Sure-Vent-1-1-2-in-PVC-Air-Admittance-Valve-with-20-DFU-Branch-and-8-DFU-Stack-39230/205395535