Thoughts on Toilets

[jackhanow]

I have an old one in my mc5. I'm not sure what model anymore and can't go look. Was leaking and not working so I started looking at new ones. Didn't like what I saw and bought a repair kit for $200.00 instead and glad I did. I think I'm gonna put that one in this bus when I get back to it.

[Iceni John]

John, you could replace the bolts with stainless ones and caulk around the foam seal, but honestly it's just a bad design. You can read about it on google.


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So, today I took my basically-unused Dometic 310 loo apart to see what all the fuss is about.   (Am I the only one who takes apart almost brand-new things even before they've been used, especially if the instructions state that it is not "user-serviceable"?!)   When I undid each of the four bolts that hold the two halves together I heard something fall off inside  -  not good.   The base easily separated from the bowl, revealing the round foam gasket under the flushing seal  that apparently is the reason for these loos leaking after some use.   What got me thinking was how to reassemble it again, because the four white plastic wedges that hold the bowl onto the base are intended to be used only once  -  the conical nuts that expand the wedges tight against the bowl's holes break off the ends of the wedges when they're assembled in the factory.   I bought four stainless 8-32 pan-head 3" bolts (the original non-stainless bolts are about 2-1/2" long with a hex/slotted washer head):  their extra length makes it possible to reuse the wedges.   I wanted to change out the steel nuts in each conical nut assembly, but the stainless 8-32 nuts I bought were too large to fit inside the plastic cones so I had to keep the original rustable Z-P nuts there.   Much vigorous shaking and swearing resulted in the four conical nuts falling back out of the bowl's four holes  -  without retrieving all four of them this project would have been dead in the water.

I ran a small bead of exterior-grade silicone caulk on the top and bottom faces of the main round gasket (the one that eventually leaks) and the thinner rectangular gasket between the plastic base and the nylon seal plate, ran the conical nuts onto the new bolts so they were flush to the end of the tapered ends of the wedges, squeezed the wedges together with needle-nose pliers so they would go inside the bowl's holes, put the loo upside down on the ground and sat on the plastic base to make sure it seated all the way against the bowl.   While sitting on it I tightened the four bolts until they were snug but not tight  - if you over-tighten them they will crack the china bowl.

I hope this will prevent the dreaded leaks/smells/puddles of pee that these loos are notorious for.   I think they're generally a flimsy design, and the seal is obviously not up to the job after it's been compressed and loses its elasticity.   Hopefully this fix will work  -  if not, at least I now know what's inside there, and it wasn't expensive in the first place if I have to replace it altogether.

Isn't life fun when you have a bus?
John

[Scott & Heather]

John, you understand now exactly what the issue is with those toilets. I could never describe it to anyone properly and even dometic acted clueless. Anyway, hope your fix works. Even exterior caulk exposed to constant urine is probably going to fail. Yuck.


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[Tikvah]

Is it safe to assume that the Dometic 320 does not have the problems that the 310 has???

[CrabbyMilton]

"Thoughts on Toilets"
I do some of my best thinking when on it.

[Iceni John]

Is it safe to assume that the Dometic 320 does not have the problems that the 310 has???

The 310 and 320 are essentially the same.   The difference is the seat  -  the 310's is plastic, the 320's is wood.   Both toilets share the same manual, and both look identical, so it's prudent to assume the 320 may have the same problems as the 310.   For peace of mind it may be worth caulking the seal now before it's used  -  my project wasn't too bad to do once I had figured out the wedges and conical nuts that hold the two halves together.

John