Black tank smell coming from Tecma toilet

[P&RD]

Hi everyone, we bought a 2007 Holiday Rambler Endeavor SKQ in 2018 and pretty much from day one, on every trip, we have been having odor issues. For the record, we changed our under sink vent caps in 2018, and we changed both roof plumbing vent caps to Lippert 360 Siphons in 2018. BUT we still have odors, mostly in the bathroom when we are parked. The toilet itself seems to be the culprit, but the odor lingers in the living area while driving. The toilet holds water fine, and I see no sign of a water leak on the floor. I found one thread that discussed a seal under the toilet that may be the problem. There are thousands Monaco's and HR's out there with the Thetford Tecma toilet. We sure would appreciate some input if anyone else has experienced this same problem.

[bhammond1980]

We have the same toilet in our 07 Haulmark. The first winter I was working on several upgrades and noticed a black tank smell. Our bathroom had carpet around the toilet so I planned to replace it anyways. To access the toilet I removed a carpeted box behind it exposing the workings. I noticed several hoses with hose clamps that I found were all loose. I used a mechanics mirror and after some frustration was able to tighten all of them. After that, the smell was gone. I have since thrown all the carpet out and built a wooden box behind and to cover the plumbing that runs along the floor. I made the lids removable in case I ever need access again. Attached is a photo after the upgrade.

[P&RD]

Very nice work. The tile and the box look great! I have less space to work with, toilet is backed into a corner. I will get in there and tighten what I can, if I need to I will remove the toilet. Thanks.

[Arch Hoagland]

While driving we keep ALL windows and roof vents closed otherwise we'll get black tank odor inside the coach.

[BobJones]

I had a minor (trace) black tank odor with the original toilet in my Diplomat. One day a part broke and I replaced the toilet with a modern Dometic 320 (?)

When I installed it I noticed that the seal was massive and completely different then the old one. Since I replaced that toilet/seal there have been zero odors including when driving and it doesn't matter what I do with the windows. That new toilet killed all odors, period.

[hypoxia]

Originally Posted by P&RD

Very nice work. The tile and the box look great! I have less space to work with, toilet is backed into a corner. I will get in there and tighten what I can, if I need to I will remove the toilet. Thanks.

The Tecma can be moved around some without disconnecting anything, just be careful with the bolts that hold it down as the porcelain is thin.

The air admittance valve could also be suspect although you replaced it a couple of years ago. https://www.homedepot.com/p/Oatey-Su...9230/205395535

[William Willard]

Originally Posted by hypoxia

The Tecma can be moved around some without disconnecting anything, just be careful with the bolts that hold it down as the porcelain is thin.

The air admittance valve could also be suspect although you replaced it a couple of years ago. https://www.homedepot.com/p/Oatey-Su...9230/205395535

The Air Admittance Valve has nothing to do with the black tank, only the gray tank -- The black tank is only vented through the roof -- William Willard

[YC1]

Welcome to the forum:

We have a 2008 SKQ with the same setup and layout of course. SKQ. Side Kitchen, Quad slides. I think that is what it means.

Owning ours since new I know ours inside and out.

Go outside to the opposite side of the water bay. This places you looking at a blank panel that does not have a door handle. Look carefully along the left side in the small space. Grab a thin screwdriver of whatever kind they used. Could be square heads or phillips. Remove them and the door will swing open. You have just discovered a new place to store things and can fashion a hidden lock as I did to make entry easier. I use two rare earth magnets about an inch in diameter near the top and bottom along the left edge. This will actually hold it closed but I added a small sliding latch along the bottom left which is out of sight.

Now to solve your problem I suspect. Look at the pipes on the right coming out of the black and gray tanks. I highly suspect the seals have gone bad around them.

But before you grab a tube of something you should cut the pipes several inches above the tanks. Don't worry, you will repair this with a simple slip joint. Once cut, carefully pull the part out of the tank. You need to eyeball how far down into the tank they were.

Those lazy installers nearly jammed the black tank vent pipe to the bottom of mine. When parked perfectly level or a bit to the left of bubble it seemed it took longer for the odors to appear. If parked to the right a bit the smells would arrive quicker.

The issue was the tank was not venting. So get things back together and you don't really need to even glue the slip joint on if you use something like eternabond around the joint.

While you have the pipes out you can do a real good clean out if you are hooked to sewer.
This leads me to the other issue I fought for a long time. The tank sprayer for the black tank was near the vent pipe. Plenty good it did spraying the tank sensors from across the tank. The sensors are on the water bay side. My sprayer jammed many times and I drilled the little holes out a bit but that did nothing for the sensors. Over time I added a sprayer close to the sensors and they have been trouble free for years now.

We full time so I was concerned that the tank might not be as clean as it could be so I removed the original tank sprayer near the vent pipes and enlarged the hole to install a clear lid screw on deck cover. I can see down inside and removing the screw on lid gives me incredible room to use whatever spray means I want. The tank has never been so clean. I did not add a deck cover to the gray tank area.
As a welcome gift I am attaching a link to all the files gathered since buying ours new in 2008. Included are files from a factory CD I bought long ago that is not available.
Upon opening a PDF you might find a yellow post it note. Mouse over them and click if needed to open them up. There will be additional information added over the years.
The files are large and will take a few minutes or longer if you have slow internet. But please download all of them and save them on something you will keep in the RV, such as a thumbdrive. Even the 240 plus page owners manual is included.
When you are interested in something specific, use your search function on the main folder of the files and as you type suggestions will come up. Use those suggestions to take you to the folder or folders where you will find more of the information.
For example, use “Bay” or “Wet Bay”, and you should come up with pictures of my wet bay modifications.
My wet bay may not look as pretty as when factory new but it is far more functional and user friendly that it was years ago. Simple thing like the drain pipe not aligning with the bottom deck hole.
Enjoy and keep in touch. PM me if you need any help with the files.

https://1drv.ms/u/s!Aqrv2TUdbV6xjjsv...0-iNu?e=dUKgev

[hypoxia]

Originally Posted by William Willard

The Air Admittance Valve has nothing to do with the black tank, only the gray tank -- The black tank is only vented through the roof -- William Willard

Odor may be subjective. I know folks that think hogs smell like money. At least they did before the packing plants shut down!

[P&RD]

Myron and Deborah,
Thanks for the enormous amount of info you have shared. That is generous of you. We will definitely review it all and keep in touch. Still fumbling our way around this site. Just today, found replies to an old thread sent last year asking if anyone removed the dinette table. You replied saying you removed the small couch. We have plans to remove it too. We are thinking of putting two leather recliners there. Secure them for travel but movable when docked. We noticed a smell coming from behind that couch as well.
Going back to that secret compartment you are talking about to access black tank. Not clear where you are directing me. Access is on the passenger side?? Inside one of the basement cabinets? I will give you my email address if you can send more info, pics, etc.?

[TXTiger]

Originally Posted by hypoxia

Odor may be subjective. I know folks that think hogs smell like money. At least they did before the packing plants shut down!

I had a girlfriend once who had a very keen sense of smell. She could tell what I had to drink, not just that I had a drink, but what I was drinking, from the smell. Course she was a big drinker herself and that’s one of the reasons we broke up.

[William Willard]

One cause of sewer smell is the washer/dryer plumbing -- If your coach is plumbed for the W/D & either no machine is installed or one is seldom used, the drain P-Trap will dry out, letting odor from the grey tank escape -- You will need to use the machine or cap the drain with a 1 1/2 inch cap -- William Willard

[YC1]

https://1drv.ms/u/s!Aqrv2TUdbV6xrRru...sHiDG?e=82dhrq

I just added these pictures to the files I gave the link to. This is a link to just the storage area. This should help some.

With the little couch out (which comes apart), you can get access to the wall that would be on the left as you are sitting there. There are often tiny staples to pull out but it is worth it for inspection purposes. The panel on the left front of that part can come off as well. Mine is back on without the screws in the hinge looking things. A simple push on type cabinet latch is used top and bottom so it can come right off.

To the left of the fireplace is a slide door that covers lots of wires and plumbing. Inspect that area closely for any leaks.

As for the tv, that is long gone and the current one is on a swivel so it can be aimed at either side of the coach. The tv mount is bolted through to the bathroom No one even notices it. There has been hundreds of hours running wires and making changes in and around the tv. The fireplace has been out so many times I installed a zipper on it.

Where the little couch lived is now populated with an apartment sized dishwasher (we live in our rv), so we use real dishes. The rest of the area is pantry and garbage can storage. The counter top is a temporary ( almost three years) but has been on the low end of the project list.

Where our large couch/sleeper lived is now holding two nice recliners. They travel with the original seat belts in place to hold them. The recliners are not swivel types but they are very easy to turn towards the television. This has worked for us for several years now.

[P&RD]

Originally Posted by William Willard

One cause of sewer smell is the washer/dryer plumbing -- If your coach is plumbed for the W/D & either no machine is installed or one is seldom used, the drain P-Trap will dry out, letting odor from the grey tank escape -- You will need to use the machine or cap the drain with a 1 1/2 inch cap -- William Willard

Thanks William. We don't have the washer option. The drain is capped.