Stinky Dometic 301 toilet - can I upgrade to 310?

[jgeurin]

I have recently upgraded to a 2018 AI GT - still have the old 2013 AI Lounge for now. Noticed a stinky smell in the wet bath that wouldn't go away no matter how clean I made it in there, or how well I flushed out the black tank, or what additives I might add to it. I found out on this forum as well as elsewhere on the internet that this is a known problem of the dometic 300 series. I took it apart, and I see the issue - I won't repeat it here, Interblog has an exhaustive treatise on the subject.

Apparently the Dometic 310 has a better design and is less prone to the problem. It requires a 10 inch rough in, as opposed to the 8.5 inches required by the 300 series. Has anyone tried putting one into a Grand Tour of the same vintage as my new rig? Will it fit? I measure right at 10 inches from the bolts to the back wall - looks like it might be a very tight fit.

[InterBlog]

Note to all - this is an Interstate-specific topic because of our wet bath configuration and clearance issues. It's not a general Airstream topic. Some of the toilet models that could potentially be used in trailers will not fit in Interstates, because of the rear clearance on the wet bath wall. I note this in the hopes that the thread will not be moved to another section of the forum.

Now, in response to the OP, you may know of this thread already (at end). The TL;DR is that many of us find the main offender to have been the Thetford, and that despite its many imperfections, the Dometic 300 series was actually a step up.



Anyway, it would be good to revisit the issue, because I don't know that anyone has done so within the past couple of years. Are there any new models on the market that do NOT tend to develop these same odor problems due to one cause or another? Are the members of the Dometic 300 series built the same as they were several years ago, or have there been design developments?

Thread:


Toilet repair or replacement in the Interstate

[jgeurin]

Well, if no one else has tried it, I may do so. I will report on this thread.

I think that there might be just barely enough room for the 310 (actually will use a 311, since this is the low-profile version of the 310 series). The "box" that the toilet sits on is several inches high already, and the 310 "standard-height" would be too tall for everyone in my family except my 6' 4" son, who is too tall to walk down the aisle of an Airstream Interstate without crouching down or hunching over. I would be surprised if such a tall person would purchase an AI. I'm only 5'9" and I still bump my head on things inside the van all the time

Will call around town today to see if anyone has one in stock. I would like to install it prior to the maiden voyage of this "new to us" rig this weekend.

[orlik]

Originally Posted by jgeurin

I have recently upgraded to a 2018 AI GT - still have the old 2013 AI Lounge for now. Noticed a stinky smell in the wet bath that wouldn't go away no matter how clean I made it in there, or how well I flushed out the black tank, or what additives I might add to it. I found out on this forum as well as elsewhere on the internet that this is a known problem of the dometic 300 series. I took it apart, and I see the issue - I won't repeat it here, Interblog has an exhaustive treatise on the subject.

Apparently the Dometic 310 has a better design and is less prone to the problem. It requires a 10 inch rough in, as opposed to the 8.5 inches required by the 300 series. Has anyone tried putting one into a Grand Tour of the same vintage as my new rig? Will it fit? I measure right at 10 inches from the bolts to the back wall - looks like it might be a very tight fit.

You may wish to review the below link to installing a Dometic 320 in a 2018 Tommy Bahama posted by Wachuko. It may help answer some install questions if you install the 310.

https://www.airforums.com/forums/f24...et-181058.html

[Janet H]

I put the 310 in an Argosy Minuet that had extremely limited space between the back of the toilet and the wall - it was the smallest configuration I could find and it fit - just. Also it's a good toilet and if needed (never have) parts are available.

If that doesn't work you might look at other marine toilets as an alternative.

Good luck

[ITSNO60]

I have the Aqua Magic V, it is 1.5 years old and no issues so far. I replaced the original which was 9 years old but we never used it so I can't say if it was having odor or leaking issues, I just replaced it because it was dirty, there was brown stuff coming out of the seam that we couldn't figure out, now I know why. I really wanted a different toilet but like IB, I did the research and there was no alternative. I can't even use the Dometic 300 as my rough in to the bolts is barely the 7-5/8" that the Aqua Magic requires and the Dometic 300 needs 8.5". Ours dumps straight into the black tank however the pipe that the flange is glued to extends down into the tank to a point below the top of the tank which may help to reduce splash.
Sounds like we will just have to replace the Aqua Magic if we start having issues, has anyone thought about filling the void with expanding foam and shaping it, then painting it with elastomeric paint to make it smooth?
Also I wonder if the short version is less likely to have backsplash as the dump hole is near the bottom of the hollow void, in Roadtrekker's pics it looks like he had the tall version and the dump hole looks to be up in there a ways with nothing to help guide the "contents" into the floor drain.
I wish I still had the old one to study but it was gross and went in the trash right away.
@jgeurin it sound like you have the short version, any chance of a picture from the bottom looking in?

[jgeurin]

Originally Posted by orlik

You may wish to review the below link to installing a Dometic 320 in a 2018 Tommy Bahama posted by Wachuko. It may help answer some install questions if you install the 310.

https://www.airforums.com/forums/f24...et-181058.html

Thanks for this link. It looks like others have had success in the 2018 AI Lounge using the Dometic 311. I have ordered one (there were none in stock locally) so I will be checking the fit next week.

[jgeurin]

Brian,

I did completely disassemble the 301, and found that liquid was somehow regurgitating into the hollow space inside the toilet. There was a yellow/brown discoloration about an inch deep in the lowest part of this cavity. The noxious odor was still clinging to this area, even though the liquid was completely evaporated. There is a gasket that may have been improperly placed, or that failed somehow. There are a several youtube videos showing application of silicone sealant to prevent this from happening. I think this one gets right to the meat of the problem and shows a hack to fix it:

https://www.youtube.com/watch?v=r5wEBuVsKIA

When I re-installed the old toilet I found, after tearing into everything and then reassembling it, that there was a new leak whereby the water trickled out of the bowl past the flush ball seal that mates with the ball-shaped valve at the bottom of the bowl. It wasn't broken 'till I "fixed" it . I made the mistake of removing that seal, even though it wasn't the culprit, once again proving the dictum "If it's not broke - don't fix it!" When I was cleaning the toilet out, I kept thinking "Why didn't I just buy a new one?" They are on sale at camping world for about $160 until May 30th.

If you go to about the 7 minute mark in the linked video, you will see the gasket that either fails, or that is improperly seated, and which, IMHO, is the weak link in the design. (There was a gasket and an O-ring on his toilet, but mine only had the gasket.) He turns the bottom section of the bowl over right around the 6:57 mark, and you can see the area where black tank liquid pools. The flat cross-hatched area at the bottom of that section of the bowl was where I saw the foul-smelling staining which to me proved that black tank splash-back had been accumulating there. Sorry I didn't snap a pic.

He goes on later in the video (at about 9 minutes) to add sealant to another gasket, but I don't think that particular gasket is responsible for the failure.

If the 311 doesn't fit in my rig, I plan to perform this maneuver on a 301 prior to installing it.

[jgeurin]

Originally Posted by ITSNO60

I have the Aqua Magic V, it is 1.5 years old and no issues so far. I replaced the original which was 9 years old but we never used it so I can't say if it was having odor or leaking issues, I just replaced it because it was dirty, there was brown stuff coming out of the seam that we couldn't figure out, now I know why. I really wanted a different toilet but like IB, I did the research and there was no alternative. I can't even use the Dometic 300 as my rough in to the bolts is barely the 7-5/8" that the Aqua Magic requires and the Dometic 300 needs 8.5". Ours dumps straight into the black tank however the pipe that the flange is glued to extends down into the tank to a point below the top of the tank which may help to reduce splash.
Sounds like we will just have to replace the Aqua Magic if we start having issues, has anyone thought about filling the void with expanding foam and shaping it, then painting it with elastomeric paint to make it smooth?
Also I wonder if the short version is less likely to have backsplash as the dump hole is near the bottom of the hollow void, in Roadtrekker's pics it looks like he had the tall version and the dump hole looks to be up in there a ways with nothing to help guide the "contents" into the floor drain.
I wish I still had the old one to study but it was gross and went in the trash right away.
@jgeurin it sound like you have the short version, any chance of a picture from the bottom looking in?

If you follow the link that Orlik gave above and go to post #47 by Alex_AVI, he has posted 3 excellent photos of the bottom of the dometic 301 (the short version of the 300 series). I think that this is what you asked to see.

[jgeurin]

After Interblog's drawing of the Thetford problem, here is a conceptual drawing that shows what I think is going on inside the 301. I have made all the gaskets/seals orange for clarity. I am not 100% sure of the mechanism of stink water getting into the hollow bowl space, but I am pretty sure that the gasket between the inner and outer bowl sections is what fails. Hopefully the solid ceramic bowl of the 311 won't even have this hollow space for waste water to collect into.

[Lotus54]

I installed one in my 2006 AI.
It was pretty easy, I also got the hand sprayer, which really makes cleanup easier.

https://www.campingworld.com/dometic...et-107006.html

[Luckysnuck]

Dometic 320 series Low Profile RV Toilet, White (Amazon link below)

Jgeurin,

This is the one you want...a no doubter. I have the same 2018 AIGT model as you and in June 2021 after almost 3 years of ownership I felt it was a time for an upgrade to the real (ceramic bowl) deal.

Removal of the old and and installation of the new was simple and the fit was perfect; zero modifications of any type required...very solid. My only pre-install concern was that this toilet's elongated bowl would make standing/showering in the wet-bath problematic, but this has proven not to be the case at all. Maneuvering my 6' 220ish lb. frame in the wet-bath for any bathroom duty seems no different versus when the smaller (slightly shorter front to back) OEM plastic round bowl was in place. After approximately 1 year of usage my only regret is that I did not swap out the OEM plastic model for this ceramic one the moment I purchased my rig new in the fall of 2018.

The approximate net weight gain with this ceramic bowl vs. the OEM plastic bowl is about 33~34 lbs., but for that home away from home bathroom experience..."go" ceramic

Good Luck!


https://www.amazon.com/gp/product/B0...e?ie=UTF8&th=1

[ITSNO60]

Although I read jgeurin's original post that he had a Dometic 300 series by the time I got through the thread and all the links I had forgotten that fact. I thought he had the Thetford Aqua Magic V which is what I (and others) am stuck with and as far as I know there isn't another toilet that will fit my 7-5/8" rough in, so I can't even "upgrade" to the Dometic 300 series as some have done. Now that I think about it we did have one issue where we had a strong odor when driving on the highway after using the black tank for several days. This was when the Thetford was less than a year old. I ended up replacing the roof vents with the siphon type, and emptying the black tank more frequently. I now suspect the Thetford leaks air even when new. My only solution is to try and seal it or go to a totally different system, meanwhile emptying and flushing frequently along with the siphon type roof vent seems to be holding the problem at bay.

I wonder if there is a marine unit that could be adapted.

[StogieMan]

We replaced ours this past February with the Domestic 311 and should have done this when we got our Interstate initially. A world of difference and feels like a toilet at home. Very easy installation and drop in as for as bolts and fit go. I had to re-plumb some of the PVC pipes and fittings though. Not hard if you have some of the PEX materials, tools and fittings.

This is the one that we got:

https://www.etrailer.com/RV_Toilets/...c/DOM67FR.html

[StogieMan]

Not the best looking plumbing job but hey I'm not a full time plumber - just a part-time Rv'er

The original toilet was plumbed right into the middle of the old toilet and this one was off set to the right if you're looking at the toilet.

Like I said pretty easy install and I added a metal shut off valve instead of the plastic one that was there. The bolts fit right in place with the old ones and the back had enough clearance.

[jgeurin]

Well, it is in now, and it fit with something like 1/4 to 1/2 inch of clearance. I went with the 311 (the low profile version of the 310). I am very happy with it. The bad smell is gone. I camped one weekend with the old stinky 301, and this weekend with the 311 and there is a world of difference!

[jgeurin]

Oh, and unlike StogieMan I needed no re-plumbing of supply pipes. Just dropped in the new unit. Perfect fit!