Thetford Aqua Magic IV
If you have a Thetford Aqua Magic IV or any Thetford model that has an overflow tube built into the rim, then you have at some time experienced the wonderful smell of your black tank via this feature.
Seems the tube is installed looking like a sideways S and relies on part of the S retaining water to prevent black tank fumes from entering the rig. As you can imagine this feature is less than reliable in preventing the fumes from entering the rig. Traveling, it only takes a few bumps to slosh the water out of the tube. Extended storage time, especially in the Texas summers, tends to make the water evaporate from the tube. And a strong breeze over the stack pipe will draw the water out of the tube as well.
The Thetford support desk has a solution to this issue and suggests you fill the overflow tube end where it meets the rim with silicone. They also stated they no longer make a replacement tube part and instruct owners to use the silicone method above to correct the issue when needing a replacement tube. Also they stopped making units with overflow tubes because of the fumes issue.
I've done this and it solved our "Smelly" issue - hopefully it will help others out as well!
Cheers from Central Texas
SPICoaster - 2008 Holiday Rambler Alumascape Suite 5th Wheel