what's the purpose of this thing?

[RPAspey]

my toilet started to smell a year or so ago, so I replaced the seal on my Thetford 4 toilet. I thought it was fixed, now the smell is back. I'm pretty sure its coming from this thing. I did look at the bottom of it.



its a tube with a drip loop, that drains into the tank. if I block it off, what problems will I create if any?

[KRS]

Is is here:

Aqua Magic IV Hand Flush Parts

[Iggy]

Don't change a thing on the toilet.

Do you keep water in the bowl always? This will seal the gasket from fumes.

If you have a sewerage smell in the room or around the toilet I bet you have the exhaust fan on and all the door and windows closed.
This will pull up the sewage smell from the tank.

Open up your rig a little so it can get some fresh air to flow in and then the fan above the toilet will extract the smells.

If this isn't the case you better learn how to really flush your black water tank properly.


Oh the hole is there in case you have a overflow and it will drain into the black water tank.

[KRS]

If that opening has a hose connected that goes to the black water tank, and the hose has a loop in it, then pour 1/2 water into the hose and it will seal the smells and not prevent operation of the overflow hose.

[RPAspey]

KRS, yes I do have the fan on, but the roof vents are open. In fact it smells even without the fan on. I have one of those turbo vents on the black vent pipe. Yes there's water in the bowl at all times. When I changed the seal, I noticed the tube didn't look the best, but I didn't really inspect it as it is hard to get to.

I didn't see a purpose for the tube at first. It simply drains into the black tank. But, looking at it now, it could be the overflow drain. The drawing KRS linked to shows an overflow drain that I don't have. IF there is a crack in the tube, it won't hold water that will keep out the sewer gases.

I guess I'll have to replace the tube.

[RPAspey]

ok. looking more closely at the drawing and my pot, the tube is the overflow. now to get the parts.

[Iggy]

I still have some questions.
Is the black tank full now or how full.
Have you been stationary for a long time with it full or partially empty?
What type of chemicals do you use?
When have you fully flushed the black water tank and how did you do it?
Have you tried filling up your tank a few times and dumping in case you has some #$%^ left in it.
I flush my with 2 or 3 times at the campground before I go home.
I have a clear 45 degree adapter to the hose outside and can see when all I get is nice clean water and no $%^& or brown water.

[RPAspey]

Iggy, I have a completely empty tank, rinsed out a few times this morning before leaving the campground. I usually empty the tank, flush by filling to about 1/2 full, and repeating the flush. I have the flush-king with extra valve so I can backfill easily. I have been using the granular TST treatment for the last 7 years without a problem. I also add the packet of dishwasher detergent that really helps with keeping the sensors clean.

Right now, with completely clean tank and no exhaust fan, the smell is barely noticable but only after lifting the toilet lid. It may sound gross, but after a thorough cleaning, I got down for a "closer" sniff, and the smell is from that overflow tube.

[Iggy]

Originally Posted by RPAspey

It may sound gross, but after a thorough cleaning, I got down for a "closer" sniff, and the smell is from that overflow tube.

That overflow tube goes down below the toilet flapper. Is it possible you have $%## below the toilet flatter in the round wider area before it goes into the PVC line and the black water tank?

[sprayking]

Also remember every couple of years the vent pipe with get so full of spider webs it wont vent properly, even with a turbo fan or a cyclone. The spiders will still get in and spin so many webs that it wont vent right. pull off your turbo fan or vent lid and stick a broom handle down it and clean it out. Whenever I have smells its either the vent pipe clogged or not enough water in the tank ( it smells when completely empty). I dont know how a overflow from the toilet will cause smells, Especially when the toilet deals with all clean water except for the water in the bottom of the bowl at the seal. Anyways just my .02

[RPAspey]

If the overflow tube doesn't have water in it to seal off the fumes, then it acts as a direct path to the black tank.

thanks for the tip, I'll check the vent tomorrow to make sure. I don't think I have checked the cyclone vent since I installed it a few years ago.

Iggy, it could be that there is some $^$^$* in that area. We drive our camper over some uneven areas before setting up. So some stuff could have splashed there. If it is connected to the black tank wouldn't it be sealed somehow from the fumes? I really can't remember what the bottom of the toilet looks like when I had it off.

[RPAspey]

First thing, the vent is clear to the tank. I could actually see the bottom of the tank.

I removed the toilet and separated the halves to look at the nozzle and overflow tube. The nozzle piece (part #12 in the the diagram link provided by KRS) fell out of its hole. The gasket that holds it in place and seals the hole, is for the most part gone. The sewer gases could just waft on up into the pot. Great! I happen to have the right gasket material for making a new one. 15 minutes later and it's fixed. Tight as can be.

While the sealant for the toilet halves is curing, I'm heading for a new floor gasket.

here's the link for the diagram:
Aqua Magic IV Hand Flush Parts

thanks.
Bob

[RPAspey]

update.... no smell for 2 trips now, even with vent fan on high. the foam seal for the overflow drain was the problem.

for anyone with that @!& smell, check the little overflow nozzle, if it is loose, it leaks black tank fumes! I think i could replace mine again in 15 minutes without removing the toilet.

[KRS]

Awesome! "waft", lol