Replaced Seal in Thetford Toilet

Metalman · 02-24-2019, 11:35 PM

I just replaced the seal in the Thetford toilet in our 2015 Windsport 27K. At first I was able to get it to seal by messaging the seal after applying silicon spray. That lasted for less than a year.

The old seal doesn't look as if it has worn, it looks as if it has been deformed, no doubt due to the constant pressure of the waste valve when closed. The color has worn off the sealing surface, but there is no ridge or evidence that anything other than the color has been affected over use.

I wonder if anyone has come up with a way to keep the seal from deforming over time? I don't believe the problem in my situation was due to over use, since we haven't spent more than fifty nights in the RV since we bought it in 2015.

Old Seal

New Seal

Lt Keefer · 02-24-2019, 11:50 PM

Toilet seals never seem to last in my coach. They always fail.

mcr1010 · 02-25-2019, 12:22 AM

When storing my RV for awhile, I drain the water from my toilet pour in a little cooking oil, usually canola, on top of the valve gate, work it a few times then put some water back in it. Has worked for quite few years on various campers.

I have had to change a toilet out once, but that was due to a mech. breakage, Knocking on wooden head, never had a seal problem so far.

Miramar Owner · 02-25-2019, 04:07 AM

I lubricate the seal with plumbers gease often... Like weekly when in use and always before storage. I've never had a problem.

saddlesore · 02-25-2019, 07:43 AM

Quote:

Originally Posted by miramar owner

i lubricate the seal with plumbers gease often... Like weekly when in use and always before storage. I've never had a problem.

times 2 !!!

Metalman · 02-25-2019, 12:14 PM

Is dielectric grease (silicone grease) the same as plumber's grease?

Miramar Owner · 02-25-2019, 01:00 PM

I don't know the answer to that but I bet "google" does. The one I use is simply called plumbers grease.

Metalman · 02-25-2019, 01:11 PM

When I Googled plumber's grease, some of the references said silicone grease, but I am not sure if they are identical.

Miramar Owner · 02-25-2019, 01:22 PM

From my understanding, plumbers grease is designed for non-potable water areas, such as toilets. Silcione grease will work just fine...it's primary use is for potable water areas such as faucets.

axis earl · 02-25-2019, 01:38 PM

Yes, silicone grease. I use a tube made by Aladdin as I recall that is primarily made for pool equipment seals.

Metalman · 02-25-2019, 02:48 PM

I have been using silicone past (dielectric grease) for other applications and will use it on the RV toilet seal. Thanks for the responses.

mcr1010 · 02-25-2019, 03:37 PM

Good idea with the silicone grease. I'll put the glove on and give it a try next time.

blw2 · 02-25-2019, 03:53 PM

mine started leaking a few years back after a prolonged sit in storage. The water in the bowl had dried. I tried almost everything I read in forums or could think of. tried throwing money at thetford buying their seal lube products, etc... all no luck
finally ordered a new seal...but before I did the job, I tried soaking it for a few days with clr...poured some in the bowl, let it soak a while....overnight...worked the valve open and closed, let it snap shut a few times, etc.... repeat. After a few days of this it seemed to be sealing again.

As I mentioned, it was a few years ago and it's still working.

Now I'm careful to keep an eye on that bowl and keep it flooded. When putting into storage I pour a small bit of the blue tank treatment stuff right into the bowel along with some water. Seems like it helps slow the evaporation maybe... Oil I'm sure would work but I don't love the idea of oil residue in the bowl..going rancid..etc...
but now that I'm thinking about it writing this maybe some clear mineral oil would slow the evaporation and also lubricate the bowl and tank regularly without going rancid and without attracting bugs and such like some organics such as vegetable oil might... and the regular bit of oil in the tank might help minimize stuff getting stuck in there on the probes and such....

Metalman · 02-25-2019, 05:33 PM

Why did you use CLR? Isn't it for a calcium build up? Do you think the chemical softened the seal?

blw2 · 02-26-2019, 09:43 PM

Quote:

Originally Posted by Metalman

Why did you use CLR? Isn't it for a calcium build up? Do you think the chemical softened the seal?

It may very well have softened...or even swelled the seal a bit.... but I doubt it. No reason to, just gut feel.

The reason I used it was that I had read lots of folks describing the cause of their leaking bowls to be mineral build up...and their solution...CLR. I can't lay claim to the idea...

Anyway, when I thought about it...my problem started at the same time that I allowed the bowl to dry out in the heat of the summer....and it's plausible that at this time minerals would deposit

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