Replacing a RV Toilet Flange

[Carl n Susan]

In the process of installing a new Dometic 320 toilet, I discovered the toilet floor flange is toast. One "T "bolt hole is broken and the other is close to it. The flange appears to be a ceramic type material.

I did the usual Google searches and found that some RVs have a glued in flange and some have a screw in flange. I am wondering if anyone has changed one on a 2012 Montana (or in that era) and which type it might be.

I hope to get the flange out tomorrow. The black tank was replaced in the past so there is a No-Hub connector on the down pipe. I should be able to remove the No-Hub and then the flange and the short down pipe will come up and out (theoretically). This makes it easier to work on a glued connection. But, being naturally lazy, if it is a screwed on flange then I prefer to just unscrew it and install a new one.

Hopefully someone has been down this road (hole) before and knows the answer.

[Jay & Bobbie]

Have you considered a spanner flange repair part?

[Carl n Susan]

Originally Posted by Jay & Bobbie

Have you considered a spanner flange repair part?

Thanks! I didn't know what that is. But Google gave me an idea. I am concerned the gap between the broken portion of the flange (now on both sides) won't be sealed by the wimpy rubber gasket on a RV toilet. I can see how a wax ring (with maybe an extension to add material to the gap) would work.

Am I missing something?

[rohrmann]

Our plastic flange broke some years ago and I left it in place and added a stainless steel flange ring on top of it. Hasn’t leaked or come loose since. I used the largest flat head screws to attach it the the wood floor and the foam gasket seals through it to the remains of the plastic fitting. https://www.homedepot.com/p/Oatey-1-...7782/303864005

[Carl n Susan]

Thanks Bob! I saw those earlier and wondered if it would work. I will run over to HD in the morning and pick one up as they are cheap. How the "T" bolts will work given the existing flange and where the screw holes lineup will be interesting to see. But if it worked for you, it should work for me (after tree or four tries) as we have the same year Montana.

[dannyrver]

Thanks for the info. Had one of the T bolts crack the flange so I ran in a lag bolt and need to finally repair. Will try the Home Depot repair.

[Jay & Bobbie]

Carl, I would love to see pictures of the repair/replacement prior to setting the WC. I've never installed one in a rv, but have installed thousands in homes.
A new wc is on my long wish list.
I assume they are very similar.

[Carl n Susan]

Jay & Bobbie: Pictures are part of the plan. I am still figuring out how to attack this problem. The "quick and dirty" fix or a more complete repair. Both involve the Oatey Stanless ring mentioned above by rohrmann.

[Hblick48]

I had a broken flange and used the ring repair. I found unpleasant odors as a result. My original ABS flange had female threads and it screwed onto the pipe going into the tank. I thought that I was going to have to break it apart to get it off. To my surprise, after removing the screws from the flange, it screwed off easily. Got replacement flange from the RV section at Lowes. Used thread sealer to install.

[laverdur]

I replaced the toilet flange in my Monty. It was black ABS and was screwed down. Very easy job. As far as the down pipe goes, one of the glued joints in mine later developed a leak. Not wanting to replace the flange again, I cut the down pipe and removed the upper section which was screwed to the bottom of the flange. Then I pieced together a new upper section of the down pipe and cut it off just short of coming in contact with the down pipe that went to the black tank. I then used a 4" flexible coupling to connect the two pipes. Been working fine for several years.

[jeffba]

Am I the only here that is amazed that Carl found an issue he has not ran into already?

[Carl n Susan]

Actually jeffba, I really haven't actually has all that many issues. But after 19 years of reading the MOC, I have heard of a lot of them. The surprising thing to me was that I couldn't find any posts here about a RV toilet flange.

I am just about done with the repair (what can I say, I am slow) and will document what I did.

[Carl n Susan]

I have finally finished the repair of my toilet flange. I never learned if I have a glued on or screwed on floor flange. I was considering undoing the lag screws holding the flange into the sub-floor until I saw how rusted they were. I chickened out given we have house guests coming and the RV is their domicile. I didn't want to open another can of worms removing them and then the flange. So I took the easy way out suggested by Bob Rohrmann.

In case you missed it, Bob suggested using a stainless steel replacement flange that screws on over the existing one. Home Depot (and others) have this available. https://www.homedepot.com/p/Oatey-1-...7782/303864005

The first task was to take care of the existing, damaged, flange. As you can see in the picture below, the toilet bolts (which hold the toilet to the flange) has been over tightened and cracked/broke the flange.



I "sanded' the flange to remove the high spots and level out the flange surface in preparation for the replacement ring. I used silicone to close the gaps in the existing flange to prevent any possible leakage.




The installation of the replacement flange was pretty straight forward. I did rotate the flange a tad to avoid the new screw holes being directly over the existing floor lag screws. I drilled pilot holes using a 1/8" bit and mounted the flange using #12 1 1/4" stainless screws. Once everything was screwed down, I ran another bead of silicone along the bottom edge of the new flange to prevent any leakage (where the red arrow is in the below picture). Lastly, i applied valve lubricant (akin to Plumbers Grease but thicker and stickier) around the ring and in the holes for the toilet bolts. Those bolts want to fall over and move when installing the toilet making it a major PIA otherwise.



A RV toilet is similar but different than a household one. A RV one uses a foam rubber-like doughnut as the gasket rather than a wax ring. Here is a picture of the bottom on the RV toilet with the doughnut.



I took a picture of the replacement ring (before installation) and how it interfaces with the toilet once installed. I used some more valve lubricant on the gasket to help ensure a tight seal with the ring.




Member Hblick48 reports he used the ring and had odor issues afterward. I am hoping I sealed the fittings well enough to avoid this problem. If not, I have another project after Thanksgiving. Ugh!

[jeffba]

Originally Posted by Carl n Susan

Actually jeffba, I really haven't actually has all that many issues. But after 19 years of reading the MOC, I have heard of a lot of them. The surprising thing to me was that I couldn't find any posts here about a RV toilet flange.

I am just about done with the repair (what can I say, I am slow) and will document what I did.

I was joking. you always have a response for everyone. which is appreciated

[Jay & Bobbie]

Good looking work.
The Oatey ring was definitely the right choice after seeing the damage to the original flange.
Thanks for the thorough explanation and pictures.
BTW, plumbing skills like yours are a rare commodity around here, if you ever feel like moving to the east coast.

[Carl n Susan]

Originally Posted by jeffba

I was joking. you always have a response for everyone. which is appreciated

I know you were. No problem.
It does seem though that I have had many of the problems seen here with my Montanas (2 of mine plus 10-15 friends) over the last 19 years.