Ventana 1/2 Bath Sewer Smell

[powerwoofs]

Hey all, have a smelly situation... I will first say my theory is the seal between the toilet and floor is the issue (if one exists... don't know the anatomy of these RV toilets yet).

On our new to us 2017 VTDP, we took a trip to Florida and the coach has been sitting for a week or two with a little bit in the black tank. Soon as we hit the road, we got blasted with sewer stank in the whole coach, and was def coming from the 1/2 bath. Windows and vents were closed. We threw some treatments in which helped about 70-80%, but could still get wiffs of it every now and then. I spent some time in there while my wife was driving and it seemed to come from near the base of the toilet at the front. The black tank is directly below the 1/2 bath. The toilet is holding water in the bowl, and seems to function fine otherwise... Parked, if I knell down by there, it seems like I can smell it still with a freshly dumped tank.

Is there a standard wax ring under these? is that compromised possibly? Something else going on? If it was leaking underneath I'm sure I'd see evidence in the bays by now, but things seem dry.

I did read some threads about possibly anti-siphon valves, but those were for DSs or other coaches. Our Baystar never had any smell issues in it.

[Dutch Star Don]

You most likely have a bad air admittance valve which is releasing the odor. It's located under the half bath sink. It looks something like this.

[powerwoofs]

Originally Posted by Dutch Star Don

You most likely have a bad air admittance valve which is releasing the odor. It's located under the half bath sink. It looks something like this.

Attachment 349177

Ok... will take a look when I get back to the coach tonight. Would that cause the smell to come from the toilet though? I've got a pretty decent sniffer and checked all the cabinets, especially the one above the toilet with the vent pipe in it and didn't smell anything in there.

[Dutch Star Don]

Temporarily bag the valve with a sandwich bag and see if the smell goes away.

Another thought.....does your coach have a SaniCon sewer macerator. If so, the short length of sewer hose that came with older models was permeable and would smell up a wet bay, which could come up through the floor.

[powerwoofs]

Originally Posted by Dutch Star Don

Temporarily bag the valve with a sandwich bag and see if the smell goes away.

Another thought.....does your coach have a SaniCon sewer macerator. If so, the short length of sewer hose that came with older models was permeable and would smell up a wet bay, which could come up through the floor.

Guessing this is it? In the hardest to reach place under the sink.... We don't have a macerator.

[Vickie 4369]

Originally Posted by powerwoofs

Guessing this is it? In the hardest to reach place under the sink.... We don't have a macerator.

Yes the large diameter round one.

My 2019 was getting a sewer smell in the 1/2 bath, when ever I ran a roof vent with all the windows closed.

I replaced the Air admittance valve all fixed.

The sick part is my air admittance valve was missing the valve inside which means it was built that way from the factory as the housing is welded and not serviceable.

So right from the day it was made it was never working.

Ted.

[Steele]

Good news is it just unscrews. Buy a better one at HD or Lowe’s.

Best $10 I’ve spent on the coach according to the boss! [emoji3][emoji2][emoji1][emoji1][emoji16][emoji38]

[powerwoofs]

I'll see what I can find at Lowes or HD. I managed to get it off just barley without having to mess with the sink fixture.

It looks fine though? Flap look fine...

[scbwr]

When I replaced one on my rig, I couldn't see any problem, but a new one took care of the problem. So, just replace it and see if it solves the problem. If it doesn't, save one of them because you may eventually need it and they are so cheap to buy.

Is your toilet bowl holding water? If it doesn't, that could be another possible sewer gas leak. I had problems with our toilet which was solved by cleaning the flapper and coating the seals with plumber's grease.

[X-OEM]

One other thought - The P-Trap under the 1/2 bath sink might not have any water in it allowing a clear path the the gray tank. The gray tank can smell just as bad if not worse than the black tank. You mentioned the coach siting for a while, that MIGHT be the case.

I don't use the 1/2 bath sink very often and have to remember to run the tap once in a while to add a cup or two of water to make sure there is water in the trap.

[Daddobbs]

We had that smell issue and only in the ½ bath. We saw something on a NIRVC video that helped us. It was the p-trap on the washer that was going dry while driving. Probably from rough roads. We put some water into the washer and smell went away.

[CWSWine]

In our Ventana LE the half bath sink is plumbed into the black tank instead of the gray tank. I verified this by dumping the black tank and turn the water in the half bath sink and water ran out the dump. Traveling sometimes we can get the smell and adding water to the sink to fill the p-trap solved our problem. We did also replace the admittance valve and didn't help.

[BonS]

If you hardly use the 1/2 bath sink and suspect the P-trap then you can pour a small amount of vegetable oil down the drain. It won't evaporate like water so it's a long term seal.

[powerwoofs]

We use the 1/2 bath a lot, and were just in the rig a few weeks ago, so don't think any p-traps had time to dry out. The toilet itself is holding water too, so the seal at the bowl is good.

Finally got a replacement at Lowes. Fingers crossed this will be the fix. We'll be on the road Monday, which should give us a good test.