Thetford Aqua-Magic V Pedal Sticks - water won't shut off

[Spongelander]

Sorry for the cross-posting on the Casita forum, and for not posting this in the Plumbing forum at first! (didn't realize we had a dedicated one) - this is quite a frustrating problem I spent a lot of time on!

If I push down firmly on the pedal, then release it, the pedal sticks on - the blade valve stays open, and water continuously flows. Sometimes it will shut off by itself, mostly not. If I reach behind the toilet and snap the mechanism the pedal operates, the valve will shut, and turn the water off. Fortunately, we have the shutoff valve to turn the water off. My research at first let me to the water valve, which I replaced; this did not seem to do the trick (and I did not have a water leak or running toilet to begin with). I tried lubricating every mechanism that moved when I depressed the pedal. This seemed to work for a while, but no longer works.
The pedal return spring appears fine, and I have cleaned the blade seal and the groove it sits in.
I went to the RV show here in Portland today, and operated every Aqua-Magic V I found installed (almost all in lower-end stick-and-tin units). In every case, I pushed the pedal down and the blade valve opened; I took my foot off the pedal, and the blade valve closed. Something's definitely sticking on ours. I searched for "Aqua Magic V sticking pedal" on the internet, and found nothing.

Am I missing something? Is it time for a new toilet?
BTW, in the inexpensive stick - and - tin trailers I visited, I found two toilets loose - one of which I could raise 1/4". Hope they catch that in the PDI...
Thank you,
Mac

[Bob & Jackie C]

Hi,
We have a 2012 Casita Spirit Deluxe we bought used two years ago that had the same problem. We replaced the toilet with a new Aqua -magic V which solved the problem. They are not expensive and easy to replace. Life is too short to spend a lot of time tinkering with some things to get them to work.
Best of luck,
Bob

[Spongelander]

Thanks - I'm a bit of a tinkerer. I pulled the toilet (quite easy) and found that the blade seal had a crust on it, which was catching the blade and not allowing it to close. I ordered a $9 seal and will re-install the toilet. What I learned is that I haven't been cleaning the seal properly - I thought the blade closed between two pieces of sealing rubber, rather than simply sliding across the bottom. So in future, if it sticks, I'll clean the BOTTOM of the seal. Also, it appears the sticking blade can be released by pushing down on it gently with any object.
If this fix doesn't take, I'll throw a new Aqua-Magic V at it...
Thanks!
Mac

[Bob & Jackie C]

Mac,
Be sure to lubricate the seal so that it will work smoothly and hold water. Be sure to keep a bit of water in the bowl. You may already know these things, but I just thought I'd mention them anyway.
Best of luck,
Bob

[Spongelander]

Thanks! The trick I learned from this was to lubricate the BOTTOM of the seal, not the SIDE, as I had been doing
I also learned that there is no toilet mounting flange as there is with a residential toilet; instead, there were just two bolt holes in the top of the black tank, with gobs of silicone holding the bolts on. I cleaned up the bolts and re-installed them in their bed of silicone, figuring the time spent waiting for the seal will let them set up.

[Borrego Dave]

Thanks for the info on the sticking slide Mac, may turn someone's camping trip into a plus instead of a minus .

[Spongelander]

Final posting - Received the new blade seal today (Thetford #31708, $9, includes a new Closet Flange Seal (the foam mounting seal) and instructions. The seal is a bit more conical than the one I removed, and it appears to be graphite - embedded - it's a gray color and has a slippery feel. Installation into the slot the old one came out of took about 30 seconds. I spent another five minutes slipping on the mounting seal, setting the toilet down over the mounting bolts, and tightening said bolts. Another minute to hook the water back up, turn it on, and test it, and all was well. I learned:
* A crust can form on the blade seal bottom over time. If the pedal sticks, put a latex glove on, and scrape the bottom of the seal. Likewise, if lubricating the seal, apply the lubrication to the bottom of the seal. I guess it will sort of sneak in if you pour the lubricant into the bowl.
* If the pedal sticks, and you must close it, use a stick or something similar to push down gently on the blade, freeing it from the seal it is sticking to and binding on.
* Five years might be a reasonable life for the seal. However, if the rest of the toilet is fine, it's not hard to pull the toilet, replace the seal, and reinstall the toilet. If I were an RV tech, I could likely do the whole process in 15 minutes, if I had the parts. I saved about $125 replacing the seal rather than the toilet. Since I'm retired, the money > the time.
thanks,
Mac