In another post I complained about the stink and smell that would never go away no matter what I tried.
Tank additives, replacing toilet floor seal, checking vent pipe, etc. Nothing seemed to work. Then I stumbled across a forum describing the toilet bowl having two separate halves that were connected with a less than ideal seal. I pulled the toilet and took it all apart. It was very apparent where the smell was; the giant POOL OF URINE AND FECAL MATTER!!! What the heck Dometic!!?? I still haven’t figured out how or when it happens, but it gets trapped inside the two halves and just sits and smells.
The fix! Take apart the toilet via 4 long screws on the under side. Then 5 small screws and tabs around the bowl to separate the halves. Clean and dry. Then apply liberal amounts of silicone wherever the seals are. Be careful with applying silicone on the oval shaped gasket style seal. The internal flushing mechanism moves close to that area and you don’t want to impede that in any way.
TLDR: The Dometic 300 can hold liquid waste inside the toilet where you can’t clean or wash without taking it apart. Caused by poor seals from the factory.
This is actually well documented as an issue with the 300. If you call them and complain, they will send you a new one. You did the fix that most people suggest. I upgraded to a 310 because of this.
You have done the community a service by posting this.
This happened to my 300 that came in my 2018 camper.
Dometic insisted they updated the design but would not send me a free replacement as I was not the original owner so I bought one on Amazon.
2nd one lasted 2 season or there about and same issue.
Dometic approved a goodwill replacement, I asked about upgrading to the 310, they approved.
310 installed and no issues yet (half a season). I have 1/8 gap between toilet and wall now as I was a solid inch plus under their rough opening requirement. It was a calculated risk and it paid off for me.
So, if sticking with dometic, upgrade to the 310 or pivot to another brand entirely.
I didn’t know this was a known issue; but I posted that this is what we found in my camper on your other post.
Crazy to hear it’s kind of a known thing with this crappy crapper.
Yeah, it’s strange, but they’re all hollow plastic, to save weight. I have a Thetford which I had to replace the flush valve, and the inside of that thing wasn’t very nice smelling, either
While shopping for a toilet 6 months ago, I found the Dometic 300 at about half price on Amazon…Thought I’d save myself a few bucks and get it…Terrible decision. The Dometic 300 is cheap, doesn’t hold water very well, and is not good holding back tank odor. I’m half hoping it breaks soon so I can justify buying a new one.
I’d just buy a new toilet that wasn’t there model. Now I need to see what toilet i have tbh. If it’s this one I’m ripping it out. Thanks for the update that’s gross as hell
Source: Solved! Dometic 300 Stink
