Toilet cassette problem

Jun 16, 2020
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Sadly we have the Dometic toilet cassette system. It has given problems since new and has even been renewed once. It seems to work on the same principles as the Thetford so my question might be pertinent to both.

The problem is, and I am aware that I am not on my own on this. That after a couple of days we have a cup full of pink liquid in the bottom. I don’t know if this is contaminated with urine. I assume it is leaking past the donut. The donut looks in excellent condition, and I have greased it with silicone grease. But to no avail. I am going to get a new donut, reluctantly as they are £26 and I do hate being so overcharged.

In the meantime, looking at the mechanics it would appear that when sliding the cassette in it goes in and up to slightly compress the donut.

Do you think that is right?

So I put some 0.5mm tape on the bottom tracks of the cassette in the hope it would squash it a little more. But the blade does not feel any different to operate. I won’t know if it will work until tomorrow.


Open to suggestions folks.

John
 
May 24, 2014
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I may be wrong, but i think the slight rise when you insert the cassette is actually to operate the vent underneath. Greater minds than mine, and khazi experts will no doubt debunk the theory.

Whether its pink flush, or ex-beer congregating in the bottom, its coming past the donut somewhere by the sound of it, so at least I think you may be on the right track.
 
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Mar 27, 2011
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This may be of no use to solve but here goes, on one occasion of emptying the cassette there seemed to be excess paper not wanting to come out through the pipe, so on the top of cassette there is a knob that can be turned and the slide can be removed, when I came to put the slide back I realised that it could be inserted either way and not know which it should be I put it in on the orientation I thought it might be and put it all back and everything worked as it should so I assumed I’d inserted it correctly, I wonder what would have been the outcome should I have put it the wrong way, also what if some small debris, let’s say tissue is stopping the slide from closing perfectly, maybe clean around the groove that the slide locates in, something like an old toothbrush run around the grooves where the slide locates.

BP
 
Jun 16, 2020
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This may be of no use to solve but here goes, on one occasion of emptying the cassette there seemed to be excess paper not wanting to come out through the pipe, so on the top of cassette there is a knob that can be turned and the slide can be removed, when I came to put the slide back I realised that it could be inserted either way and not know which it should be I put it in on the orientation I thought it might be and put it all back and everything worked as it should so I assumed I’d inserted it correctly, I wonder what would have been the outcome should I have put it the wrong way, also what if some small debris, let’s say tissue is stopping the slide from closing perfectly, maybe clean around the groove that the slide locates in, something like an old toothbrush run around the grooves where the slide locates.

BP

Thanks, it’s been completely striped and clean a few times. I am pretty sure on this one that it will only go back one way. But worth a though nevertheless.

John
 
Oct 8, 2006
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Not being familiar with the Dometic, on our Thetford when you move the trap lever in the bathroom the trap cover lowers slightly then swings sideways, doing the reverse when you close it. The lowering and swing mechanism, like the rest of the inside of the waste container, is very prone to collecting calcium carbonate which can stop the mechanism operating properly. You would probably not be aware of the small gap that results on the top of the trap cover and lets liquids get out.

On a Thetford the whole mechanism can be removed as part of the access plate in the top of the container, yours may be similar. I would suggest you take it out and soak it in a bucket of warm water and (preferably white) vinegar overnight. In the morning clean any remnant debris with an old toothbrush or similar, rinse it thoroughly and refit. You can do the same with the container body at the same time if you wish.

Alternatively if you feel rich buy a bottle of waste container cleaner, pour it into the container through the trap, add a litre or two of warm water and shake it up to dissolve the cleaner, then fill the container to over flowing with warm water - you may need to pour the last bit in through the exit pipe. Leave it overnight and then rinse it thoroughly with cold water.

Lastly, if you remove the access plate it is easy to remove the rubber seal above the trap. Clean it well with warm soapy water including inside the central 'gap', rinse it and dry it with kitchen roll. Before putting it back into its mount using a finger (in a disposable glove) wipe olive oil liberally all over it. Rather than use your Management's best extra virgin oil, you can buy a small bottle of pure olive oil from your local pharmacy for about a pound.
 
Sep 21, 2007
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We have a Thetford but could be similar.

The brackets that hold the bowl to the base of the toilet, also allowing it to swivel, became loose. We found that when sitting on the loo the bowl was moving excessively which was breaking the seal to the 'donut' allowing fluids to pass and end up in the bottom of the cassette compartment. I just retightened the 6 screws and problem was solved.

I've attached a photo showing 2 screws in one bracket. There are 2 more brackets.
20210614_113014.jpg
 
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