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Old 04-19-2021, 04:36 PM   #1
Cindy and Ray's Grand Tour
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Location: Converse
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M.O.C. #21053
Dometic toilet won't stop drizzling or hold water in bowl

Hi all, Just got my Monty out of 6 months of storage and getting it ready for our summer long tour. Everything seems great except my Dometic toilet (210 I think) has a very slow leak into the bowl while at the same time my bowl gasket won't hold water. It probably got too dried out. I will try some cooking oil on it tomorrow as others have suggested. However, once it holds water, the bowl will flood over from the fill leak. How easy does the flush lever come apart and are there new washers that can be put in? Has anyone tried any other easier tricks.

I just had the new Dometic installed to avoid issues like this. I only used it for two months since installation. I am a terrible handyman so this rather frustrates me.
Ray, Cindy, Goldie the Lab & Nikita the cat
2018 Montana 3791RD
2017 RAM HD3500, DRW, Cummins Diesel
Converse, TX
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Old 04-19-2021, 05:07 PM   #2
Carl n Susan
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M.O.C. #4831
The seal is easy to remove. With the water off, open the flush valve, grab the seal and pull it upwards. You likely will find dried "stuff" on it that allows the water to leak. Clean it up and re-install. Leave the flush valve closed and position the seal back ensuring the ring engages the groove. That should cure the bowl mnot holding water problem.

As for the fill leak, I am stumped. That is a well known Thetford problem. I haven't heard of the problem on a Dometic 310/320. Not that it hasn't happened.
Carl (n Susan)
There is more to life than fuel mileage.
2012 Montana 3700RL Big Sky Package towed by a 2015 Ford F350 6.7L PSD 4WD CC LWB

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Old 04-19-2021, 07:42 PM   #3
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M.O.C. #12947
Was this trailer winterized? If not and if there was water in the flush valve of the toilet, it is likely it froze and the valve will need to be replaced. A new valve is not hard to replace.
Bob & Becky
2012 3402RL
2012 Chevy 2500HD D/A CC 4WD
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Old 04-20-2021, 04:12 AM   #4
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M.O.C. #25165
I had a similar problem with our original Thetford toilet. I cleaned the seal as Carl suggested and put in some Thetford Seal Conditioner and let it sit while the rig was in storage for a couple weeks. No problems since. I got the seal conditioner on Amazon.
Robert & Diana McNeal
2019 Montana Legacy 3791RD 20th Anniversary Edition
2014 F350 4x4 6.7L SRW
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Old 04-29-2021, 04:37 PM   #5
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This post was timely for me. We are currently in Texarkana after leaving San Antonio two days ago on our way to northern Wisconsin. We had the Dometic 320 installed in the summer of 2018 and only used the rig once after that in October of 2019. We store it under cover but we are in South Texas. After setting up in Texarkana we noticed the toilet was not holding water. Removed the gasket, cleaned everything well, replaced it and still not holding water. Was able to find a replacement gasket locally. I'm not that handy but with DW help I was able to install the new one. Tip: when you replace the gasket put your (gloved) hand in and pull up on the gasket to seat it. I tried to "push" the gasket into the groove with no results before I tried to "push up" on the gasket with DW holding the pedal down with her foot and it worked!
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Old 04-29-2021, 04:52 PM   #6
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Maybe you two could do a YouTube video of that procedure 😂
Bob & Becky
2012 3402RL
2012 Chevy 2500HD D/A CC 4WD
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Old 04-29-2021, 09:28 PM   #7
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here it is, does not look to bad

al meyer 3931fb
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Old 04-30-2021, 11:13 AM   #8
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M.O.C. #21903
I have a Dometic 310. When I put it into storage, I always add extra water to the bowl. Then I pour a little holding tank valve lubricant into the bowl. It sinks to the bottom and keeps the seal moist and lubricated.
'05 F250 6.0 Bullet Proofed
'02 Montana 3280RL Upgraded a bunch.
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Old 04-30-2021, 07:58 PM   #9
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I also have a Dometic. I take plumbers grease and coat the seal when I store it for 9 months.

Tom and Gail
2013 Mountaineer 362
2012 Silverado 2500
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Old Yesterday, 06:35 PM   #10
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M.O.C. #19032
In ND winters are long and my rig is stored for 7 months. Even though I blow out the system to start with I still pump about 2 gallons of RV anti freeze through the system to fill all the valves, traps, and I leave an inch in the bottom of the 320 toilet. I have never had issues coming out of storage. I think it helps to keep things “wet”.
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