Dometic Toilet Cassette Seal Leaking

Do you have a Dometic or Thetford cassette toilet?

Struggling to get that cassette to open and close?


Lubricating the cassette slide-out

I have had a Dometic cts3110 (same cassette as cts4110) for 9 years and from very early in its life I started to spray the 2 stainless rods behind the plastic handle as well as the black plastic slider with Silicone spray. To this day I can say it does wonders. After changing cassettes, my wife is quick to ask me to spray “that handle thing”. I use the cheap StaLube cans from Bunnings. It lasts long and works great. I tried the Marine silicone spray as well. It is much more expensive and didn’t seem to last any longer nor do the job better.

Here are some more brands that may work as well:

[amazon_link asins=’B00D3ZKVAS,B0001FYL2M,B00631GSSI,B000HBM5S2,B0019LV3GO,B0013J62TU’ template=’ProductCarousel’ store=’rvm0504-20′ marketplace=’US’ link_id=”]

Necessary cleaning procedure

From time to time, lets say once every 3 to 5 months, it may be necessary to remove the scale build-up from the bottom of the 2 stainless steel rods. If it is left too long, it will start damaging the rubber seals and leakage can occur. Be careful when using a sharp instrument, not to damage the steel rods as that will in turn damage the rubber seals.  An old credit card  or similar plastic card may be the right thing for the job. Clean off the scale and cover with ample silicone spray to minimize build-up.


Here is a quick link to Amazon Silcone Sprays


What to do when the pullout seals are leaking

There are no replacement seals available and no way to get to them. You will need to either buy the complete cassette slider valve or a new cassette. That is why it’s so important to look after the cassette from new.

I hope you found some value from this post. If so, please leave a comment. It will be highly appreciated.


Leave a Reply

Your email address will not be published.