Help!!!! Really bad sewer smell coming from toilet

Bobby-D · 06-20-2023, 04:21 PM

Hello!
We own a 2022 Micro Minnie FLX.
We are having issues with our toilet/black tank.
Basically, there is sewer smell that fills the trailer as it sits over night/through the day. It smells like it's coming from the base of the toilet. We always make sure there is water in the toilet to make sure the seal inside the toilet bowl is covered. We also make sure we run water in the bathroom sink to fill the p-trap and to close the drain plug in the sink (I have read some Winnebago bathroom sinks run into the black tank). The smell doesn't seem to be coming from the bowl, but rather from the base of the toilet. We've taken back to the dealer 3 times; they've done a smoke test and filled the black tank until the water was into the toilet bowl and haven't been able to find any leaks. However, the last time we took it in, they had to fill and drain the black tank 6-8 times to get the smell to leave the trailer. We have tried using Happy Campers black tank treatment, the orange blank tank treatment made by Campco, and the blue stuff they sell at the dealer. Any suggestions are appreciated, I feel like I'm losing my mind!

TravatoJohn · 06-20-2023, 04:41 PM

You should start using Pine Sol every time you dump. Put 5 gals of water in and add one cup of Pine Sol. See if that helps. It’s a degreaser.
Travato John

Bones2003 · 06-20-2023, 04:42 PM

Have they checked to see if the vent on the roof is clear and connected to the black tank? If it was plugged, I don't think the black tank would drain very well but that would depend on how the whole plumbing system is laid out. If it wasn't connected, I think you would probably see some type of leakage unless maybe the pipe is damaged part way up.

Morich · 06-20-2023, 05:20 PM

We get little to no info on trailers, so we are limited in what we can research but there is a possible cause which we CAN see on drawings for many motorized.
Possibly you can spot a potential cause by looking?

Are you familitar with "air admitance valves"?
What can hapen is that the air in a grey tank and a black tank can smell very much the same, so we can be mislead by our noses! OR if you are dealing with a vanity which drains to black, you may be correct and smelling black!!

If you look underneath the vanity, you will likely see the drain going down to a trap of some sort before going to a wall and heading down. Somewhere along close to the wall, there may be a pipe going up for just a short distance. Foot of less? And at the top there may be a valve which is something like we might call a check valve or one way valve.
The idea is that as we drain the vanity, water should be left in the trap as a way to seal odor from coming up, through an empty trap and into the room.
The problem the air valve is meant to prevent is when water fills the pipe going down, it can create a vacuum behind it and pull the water from the trap along with the rest!
So they add a flap gizmo in the air admitance valve so that the vacuum is relieved as air enters at the valve!

Info from RV drawings but certainly not meant to show what you actually have???

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They often just screw onto the pipe and are easy enough to change but you may find you have one under one or more of your vanity or sink bowls. One may be stuck open to let the odors come straight into the RV!

Sometimes a wild shot at changing a cheap item is better than fighting the system to get them to fix the simple stuff? Newer/different RV may have different items in this place, making my name for them "old style" but they do the same and fail the same way!

Best of luck on the chase.

Fred 2106DS · 06-20-2023, 07:34 PM

A couple years ago we started having a sewer smell in our Micro Minnie after it would set for a few days when not being used. I replaced both OEM vent caps with Lippert 360 Siphon Vent Caps and the smell went away and hasn't returned. Apparently at least one of the OEM vent caps wasn't creating enough vacuum to draw the smells from the waste tanks when our Micro Minnie was setting and not being used.

Bobby-D · 06-23-2023, 04:12 PM

Thanks to everyone that replied!
I think we figured it out.
My wife did a deep dive on the Internet and found out that the Dometic 300 series toilet is notorious for leaking on the inside of the toilet and producing a terrible sewer smell in the cabin. We went inside and looked, and wouldn't you know it, we have a Dometic 300 series toilet in our unit. I took a picture of the inside of the toilet with my phone and saw urine and feces water that is building up in the toilet. Winnebago towables has not been much help, and my dealer told me today it would take another 1 to 2 weeks to get a new replacement toilet (even though the trailer has spent 5 weeks at the dealer with this problem already and they couldn't figure it out). I called Dometic and they are shipping me a new 310 series toilet on Monday (get here by next Thursday; a week from now). I looked on Amazon and realized I could order a new 310 series and have it delivered tomorrow, so I'm doing that as well. I'll let you all know if this is the actual fix. Thanks again!

KT in AZ · 06-25-2023, 04:21 PM

We had the same problem a few years ago with a Dometic 300 smelling like a sewer. The only way to ensure a fix was to upgrade to a 310. I am surprised Winnebago is still putting 300’s in their new towables because this was a widespread and well-known problem years ago. If Dometic offers a 310 in replacement, you should take it. They only offered to send another 300 as a replacement when we had our problem and it was well-documented that the problem was likely to reoccur unless you got rid of the 300 and upgraded at your own expense. The whole experience left me with a sour taste (and bad smell) about Dometic to this day.

raj · 06-25-2023, 09:33 PM

Yep, the Dometic model 300 is apparently pretty well known for smelling like a sewer. I changed our unit to a model 310 and haven't had any problems since. I have to also say that the porcelain toilet bowl feels a lot more secure as well! No more creaking plastic, says the wife!

dnrainey · 06-27-2023, 06:46 AM

Glad you solved your problem, but I would also recommend installing either the vent previously mentioned or this one, the Cyclone Sewer Vent. I have used these for several years and never have any smells in the coach. https://www.campingworld.com/cyclone...ent-31992.html

raj · 06-27-2023, 03:36 PM

I bought one of those "Cyclone vent" covers and then found that my roof ladder is so close to the top of the vent that I couldn't use it, so I gave it to a friend. For now, the smell seems to be solved by the replacement of the toilet with a model 310.

tinglett · 10-10-2023, 06:54 AM

Add me to the list of those who had to replace the cheap Dometic 300 with a nice 310. Our bathroom started smelling more and more like urine and I was thinking the vent may have been blocked as discussed earlier in this thread. Nope. My wife made the observation that it smells more like pee than sewer in general.

I replaced with a 310 and now that problem appears to be gone. We'll see over the next weeks, but I think that was it. The 310 is so much nicer anyway. None of that embarrassing creaking

.

Also, this had to be the easiest repair I've ever done. Remove water hose fitting, loosen two bolts, remove toilet, finish install in reverse. I'm not sure it even took 15 minutes.

Laurachrissy · 11-01-2023, 05:15 AM

Quote:

Originally Posted by Bobby-D

Thanks to everyone that replied!
I think we figured it out.
My wife did a deep dive on the Internet and found out that the Dometic 300 series toilet is notorious for leaking on the inside of the toilet and producing a terrible sewer smell in the cabin. We went inside and looked, and wouldn't you know it, we have a Dometic 300 series toilet in our unit. I took a picture of the inside of the toilet with my phone and saw urine and feces water that is building up in the toilet. Winnebago towables has not been much help, and my dealer told me today it would take another 1 to 2 weeks to get a new replacement toilet (even though the trailer has spent 5 weeks at the dealer with this problem already and they couldn't figure it out). I called Dometic and they are shipping me a new 310 series toilet on Monday (get here by next Thursday; a week from now). I looked on Amazon and realized I could order a new 310 series and have it delivered tomorrow, so I'm doing that as well. I'll let you all know if this is the actual fix. Thanks again!

Was the toilet the source of the smell and did the new toilet solve the issue?

Ray,IN · 11-01-2023, 05:37 PM

Quote:

Originally Posted by Bobby-D

Thanks to everyone that replied!
I think we figured it out.
My wife did a deep dive on the Internet and found out that the Dometic 300 series toilet is notorious for leaking on the inside of the toilet and producing a terrible sewer smell in the cabin. We went inside and looked, and wouldn't you know it, we have a Dometic 300 series toilet in our unit. I took a picture of the inside of the toilet with my phone and saw urine and feces water that is building up in the toilet. Winnebago towables has not been much help, and my dealer told me today it would take another 1 to 2 weeks to get a new replacement toilet (even though the trailer has spent 5 weeks at the dealer with this problem already and they couldn't figure it out). I called Dometic and they are shipping me a new 310 series toilet on Monday (get here by next Thursday; a week from now). I looked on Amazon and realized I could order a new 310 series and have it delivered tomorrow, so I'm doing that as well. I'll let you all know if this is the actual fix. Thanks again!

Use a new gasket under the toilet, Once the old ones have a set in them it can be hard to get them to seal properly..