Smell from rear cabinets 26RBS

[BigJimsCamper]

Per the title .. we are getting a bad smell from the rear cabinet area on our ‘23 26RBS. I’ve figured out it is coming from the gray tank .. but can’t figure out why smell is entering the the rear cabinet? Occasionally I smell coming from beneath the shower base too? Appreciate any thoughts. Jim

[Mikendebbie]

Looking at your floor plan - I sketched in my guess at two possible locations for your black tank. The toilet may not be directly over the tank so it may have a short piece of pipe to connect it to the top of the tank. If the tank is in the rear location the toilet will drop directly into the tank. There is also a vent pipe coming off the tank (see roof pic).

I would check to see if toilet pipe is properly installed and not leaking sewer gas. Same thing for the vent pipe and the discharge pipe. If this was on my unit I would have to remove the coroplast bottom cover to look at the tank - I think Cougars have coroplast bottom also.

Search YouTube for “Keystone Cougar factory tour” and watch a few videos to get a better feel for how the tanks are mounted down in the frame.

[BigJimsCamper]

Thank you for your reply. Your drawing is exactly right. I’ve figured out the odor is coming from the gray tank (cleaned the gray tank and odors went away). Sorry .. two questions .. do the black and gray tanks share a vent (only one on the roof) .. 2) how hard is it removing the insulated liner under the unit? Do I have to remove whole thing or just enough to view rear compartment. Thanks!!

[chuckster57]

How many waste tanks do you have? If for example you have 1 black and 2 grays you should have 3 vent caps on the roof. I have seen 1 vent cap for 2 gray tanks mounted next to each other but I’ve never seen a black and gray tank share a vent.

[BigJimsCamper]

One black tank and one gray tank (in rear) and sdd’l gray tank near front kitchen sink. It’s odd .. only one vent pipe on roof (in the rear). I’ll reach out to Keystone and see if they can give me any advice how the gray tanks are vented? There is an admittance valve under the rear sink .. I wonder if that is the only vent for the rear gray tank? Thank you for your help!

[NH_Bulldog]

The grey tanks need to have their own vents for a number of reasons. One of which is that water draining into the tank needs to displace air, and that air needs to go somewhere (out the vent), otherwise your drains won’t drain. It is entirely possible that Amos forgot to cut the hole in the roof the day yours was built. It is also possible (although unlikely) that they ran out of roof vents and tied the black and grey vents together.

On a related note, what type of refrigerator do you have, 12v DC or gas/electric absorption?

[bobbecky]

It's also possible that there isn't a roof vent for the grey tank and instead they installed an AAV (air admittance valve), and that is what is leaking the odor.

[chuckster57]

If you have air admittance valves, it’s possible it has failed.

[NH_Bulldog]

That is always a good thing to check. If it is unscrewed from the pipe it should rattle easily.

In a functioning system, keep in mind that an air admittance valve allows air INTO the system but a vent is what lets it out.

[JRTJH]

^^^What Rob said. An air admittance valve will help introduce air INTO a drain line that might have some slow draining from long horizontal runs (as one example), sort of like putting your finger over the end of a straw holds water and moving your finger allows faster flow.

There's still going to be some sort of "above the tank vent" to allow air out of the otherwise closed space that would be a pressurized balloon as it fills with waste water without the roof vent. If the air admittance valve were to act as a vent, then ALL the smells from the tank would flow up into the cupboard where the AAV is located. That's NOT a pleasant smell !!!!!

[foldbak]

Here's another option. Put one on my rig, smell gone. https://www.amazon.com/Ultra-Fab-53-...04UQV3II&psc=1

[GlasNav]

Isn't it a new unit?
Wouldn't this be a warranty issue?

Truthfully, tell Keystone their trailer "STINKS" fix it!

[Stangfire]

As mentioned The AAV can cause an odor if it's failed. As well as the anti-siphon valve. In my case both of these were located under the bathroom sink. My anti-siphon valve was installed the wrong way. (vertical orientation instead of horizontal)

[chuckster57]

Originally Posted by Stangfire

My anti-siphon valve was installed the wrong way. (vertical orientation instead of horizontal)

Anti siphon valves are supposed to be vertical, not horizontal. The incoming line at the bottom and the outgoing line on the side.

[Stangfire]

Originally Posted by chuckster57

Anti siphon valves are supposed to be vertical, not horizontal. The incoming line at the bottom and the outgoing line on the side.

Perhaps I worded that wrong. This was my original post of the issue.

https://www.keystoneforums.com/forum...ad.php?t=56014

[Julie D - Austin Tx]

BigJim,

We had the same problem with the exact model Cougar - but our smell problem was solved when some low-life waste of flesh stole our RV from our storage yard around February 12, 2024. The scumbag caused us much more misery than the smell ever affected us. Now I hope the smell is worse than ever to make the bass turd suffer. If you can’t tell from this post - I am still just as angry now as I was the day the *$#@*** person hitched it up and drove away with MY TRAILER and all our personal belongings!

I hope you get your issue solved. Good/not good to know it was from the Factory and not something our dealer did to the 26RBS. I don't know if we'll use the same dealer, mostly because we are looking at a few other TT models/manufacturers.

Julie

[foldbak]

I had a similar problem, black tank odor coming from under the bedroom steps. This only happens in summer. It was at the dealership twice for it. They couldn't find anything. I suspect it's a two fold problem. Number 1, why only summer? Water evaporates! I discovered that when it's hot, if I continue to add water and pods when not in use, I don't any odor. Number 2, I believe there is a bad connection on the vent pipe allowing the odor to escape under the stair vents. The vent pipe is in the wall, so finding the problem impossible. With added water, pods and the solar roof vent, no more odor. FYI, I did see a picture of a vent pipe with a hole in it from a hole saw. Came from the factory like that!

[Domino3665]

Don’t rule out a dead mouse. ��

[dutchmensport]

The photo of the roof does not show where the bathroom roof fan/vent is located. But, if the black tank vent (the black round thing on the roof) is too close to the bathroom ceiling fan/vent, odors can (and do) come back inside the bathroom through the fan/vent when the wind blows just right.

This may not be your problem, but it is one thing to consider.

But, I'd sooner believe it's your air admittance valve under the sink. I can't imagine the black tank anti-syphon check-valve under the sink is the problem. It's sealed. To test, hook up your garden hose to the black tank flusher and turn on the water. IF the black tank anti syphon valve is cracked, you'll have water spewing out of it. If so, THAT could be the source of the smell. If no leaks, then it's NOT that valve.

Good luck!

[Herb51]

Hey all, just came across this and thought of a problem that I had. Same thing, bad smell in the bathroom and BH area, Spent half a day looking for the problem, cleaning the black water tank, checking for leaks. Then it happened, this older gentleman came walking by during one of my many breaks, and asked what was going on, I explained the problem, and with a smile, he told me to check my vent pipe, run a water hose down it, if it hits the bottom, all good, I tried his suggestion and half way down I hit a blockage, turned the water on and up from the depths, came, Wasps. And now, the rest of the story, I clean my vents every year. I never saw that old man again, but if you see this, thank you.