Tab 400 BD Black Tank Flush leak

mjwaldner · April 2021

I figured out today that I have a leak at the PEX connection to the Black tank. Not on the nautilus side but the black tank under the toilet side.
Reading the forum it sounds like this was a problem for others and they were able to access it through the outdoor shower but on the 2021 versions, they no longer have the outdoor shower in that location. I can see the leak using a flashlight, mirror on a retractable extension through the sub-shower access hatch. But I don't see any way I could get even close to this area with an arm or tool.
There is a lot of plumbing and the air duct to the bed area in the way. I looked at removing the sink module to get to it but it's below the shower floor pan so I don't see a way at it in that direction.
I'm concerned that the only way at this is to remove the sink assembly, toilet and then remove the floor of the shower. Uggg. I'm going to try and remove the air duct under the bathroom and see if I can reach it but that does not look promising.
Anyone have a picture of how the black tank is installed at the factory I can look at for reference? Or any idea how to get to this area.

Denny16 · April 2021

MJ, are you referring to the black tank wash connection to the black tank? The shower pan is a one piece unit, including the cover over the black tank that the toilet sits on. Not sure you can access the black tanks ash down connection from the sink unit. You could put a call into nüCamp Service, and ask Austin how to get to this area.

That said, your 2021 TaB400 should still be under warranty, or at least this issue should be. I would contact your dealer to have this sorted by nüCamp and the dealer. No way through normal use this connection should have come loose. Sounds like a factory issue, with not getting the connection tight in the first place. Given the inaccessibility of this connection, it should have been doubled clamped, to prevent it ever coming loose.

Paul the Air Force guy did a walk through factory tour of a 2019 TaB 400 build, and it shows how the black tank is installed. Also Verna had some shots from her factory visit.

Meanwhile, the black tank is still useable, just do not use the tank wash down, and it will not leak in normal use. Empty the black tank when it gets 3/4ths full to keep black water from splashing up into the connection, which is at the top of the tank.

This is what is behind the sink unit. As you can see, the two PEX tubes (red arrow) go from the wash down connection to,a,check valve behind the bit of plywood (down red arrow) and then back down the right side tube to the black tank. The only connection you can access here re the two check valve connections. You need to remove the tank cover the pipes go down through.

The only other option I see to access this connection, is to install a door opening, like the shower door on earlier models, so you have access to the connections. But you are going to need to know about where the fittings on the tank are to get the opening in the right spot. This is a major undertaking, and something you should not have to do.

mjwaldner · April 2021

Thanks, Denny,
Can you repost the image your describing? I don't see it attached.

Denny16 · April 2021

@mjwaldner OK, I reposted the photo above. It keeps disappearing?

Cheers

mjwaldner · April 2021

Danny, This is very helpful. I went back and looked at it again and I now realize it's not the connection to the black tank but the connection to the 90deg fitting that goes up to the check valve (it was hiding behind a black suer line). Not sure if that makes my life any easier but it's good to fully understand the problem before attempting to fix it.
With regards to it being a warranty issue, I would agree this should be 100% covered under warranty but based on past experience at the dealer fixing all the other problems this unit had out of the factory I would not bring this into that dealer ever again. And they are 2 hours away and I'm not making that trip again for any reason.
I don't want to break off into a rant and I love this Tab 400 overall, but there were so many things wrong out of the factory I'm having a hard time loving NuCamp right now. I'm sure I'm a victim of the Covid-19 push but they should not let their quality drop down due to high demand.

Denny16 · April 2021

Sorry you have a bad dealer experience, Any other dealers in your area?
At a minimum, you should at least contact Austin to get any recommendation he may have to access this fitting and repair it. Doesn’t cost anything to ask. I would also contact nüCamp Customer Experience and let them know about the bad dealer experience, the can not fox something they do not know is broken.

Given your location, a road trip to Sugar Creek to nüCamp would be worthwhile to get this and any other warranty repairs sorted out, including the ones the dealer messed up.
cheers

mjwaldner · April 2021

Good news. I was able to find a way to get to the leaking connection. This is how I got to it. Not sure if there is an easier way.

This is the fitting that was leaking. In this picture, I'm looking at it through the access panel below the bathroom using a mirror and a flashlight. No way that I can see to get at it from this location. The curved foam is the front of the wheel well for reference. The black plastic in the upper right is the flexible air duct running to the bed area.

Image: https://us.v-cdn.net/5021717/uploads/editor/kw/vpte4oa7pr43.jpg

I removed the drawer and cubby compartment below the 3-Way refrigerator (closet on the 2-way refrigerator version).
I was able to squeeze in on my back and stick my left arm through the hole that the black flexible air duct is running through. The duct can be compressed enough for my skinny arm to get through. If you're a big person it might be time to recruit someone skinny. The edge of the wood scraped my arm up so I would recommend long sleeves. At that point, I was able to hand tighten the fitting and stop the leak.

Image: https://us.v-cdn.net/5021717/uploads/editor/7z/vw7ed7fvg1yp.jpg

I hope this helps anyone else that has this problem.

Denny16 · April 2021

Grand, glad you got it sorted, this saves you a trip, which may have been an interesting adventure...

cheers

xdr · April 2021

What evidence did you have that made you realize you had a leak? We are de-winterizing and sanitizing now and I’d like to be on the lookout for it.

xdr

mjwaldner · April 2021

I guess I was just lucky. I was adjusting the faucet in the bathroom as it had come loose and had the under-sink compartment open. I saw the two white water lines you can see in Denny's picture and did not know what they were for. My curiosity got the best of me so I tried to figure out what those lines were for. So I opened up the below bathroom compartment to see if I could see where they were coming from. When I was looking in the mirror I noticed water on the connector. That morning I was flushing the black tank and apparently, there was some water still on the connector. After tracking it back to the black tank flush inlet, I had my wife turn the black tank flush on again when I was looking at it and a decent amount of water was dripping out. I'm glad I looked but now I'm nervous about what else is waiting for me to find.

stmur7 · June 2022

Hi. I used my black tank flush for the first time today and water began leaking below my new 2022 Tab 400 on both sides of the wheel. I found more water in the shower around the toilet (but don’t think it came up from the toilet bow)l. Also, some water on floor below table. I’m really sort of devastated. I found no water under the bed in the compartment with all of the Nautilus and Alde mechanics. The water does not seem nasty or smelly. The dealer is so backed up it could be many months before I can get an appointment. Can anyone give me some advice? Am I safe to use the tanks? Thanks in advance.

manyman297 · June 2022

There’s a check valve for the black tank flush behind the bathroom sink. Many on here have had issues with it not being tightened (among many other plumbing fittings unfortunately). My guess it it’s the culprit in your situation.

The good news is you probably haven’t damaged anything since your subfloor is composite and not plywood.

The bad news (well, not that bad) is you’ll need to access the backside of the sink to get to the check valve to tighten it. Not fun but not that hard to get to.

While you’re at it check the tightness of all of the plumbing connections on the backside of the nautilus panel (under your bed). Mine leaked but I was able to catch it before any damage was done.

They must still be employing somebody with arthritis or carpal tunnel because these loose fittings have been an issue going on two years now.

mjwaldner · June 2022

Open the compartment under the sink and see if you have water in that area. Look at the picture above from Denny to figure out what you're looking at. The check valve is behind that wood panel in the picture.
If it's the black tank check valve you should be fine to use the black tank. Just don't use the flush. Get it fixed when you can.

Denny16 · June 2022

Since you have a new TaB, I would be taking this back to the dealer with a punch list of things to check ad correct, including all the plumbing connections and the black tank flush, to make sure the the check valve is the correct way round, sounds like it is not, and a loose fitting is allowing water to leak into the trailer. Good news it is fresh water.

88keys · June 2022

@mjwaldner - I think I might be having the same issue you had. Water goes through black tank, however a good steady stream comes out front of wheel well also. Checked all other connections, nautilus and behind panel under bathroom sink and no indication of leaks in those areas.
How did you remove drawer and cubby panels? Can't seem to get the drawer out, it must be so simple that I'm over thinking it. I've extended the drawer and moved the side levers up/down, but it still isn't coming out.

mjwaldner · June 2022

The little levers on the sides of the drawer slides should move in opposite directions. After that, you need to give it a little force to get it to slide out. The cubby is just held in by a few screws.
But, if you are getting water coming out the weel well it sounds like you either have a very big leak or the water is coming from some other place. I would think you would be finding water on the gally floor if you had a big enough leek to get out to the weel well. There are only a few penetrations through the floor of the camper.
If you remove the access panel below the bathroom (in the gally area) look under there and see if you see water. It could be your shower drain or trap is loos. there is a penetration right there.
Also, remember the fresh water tank is between the wheel wells going across the whole camper. There are several places that could leak if a pipe was damaged or not installed correctly.
Also if you completely fill the water tank the overflow on the driver's side is just behind the wheel. Make sure that's not where the water is coming from.

manyman297 · June 2022

I believe the wheel well spans from the drawer (under the wardrobe) into the bathroom area so feasibly he has a check valve leak. I've been under there to install a surge protector and I'm pretty certain the wheel well goes between both areas.

@mjwaldner pics show the area perfectly.

Denny16 · June 2022

On the TaB400 the driver’s side wheel well is between the rear bunk and the washroom shower area, behind the cubby and drawer under the wardrobe locker/larger fridge area. Access is by removing the drawer and un screwing the rear panel of the cubby.

On the early TaB400s it is under the wardrobe locker floor, whihc has a lift up access panel, and behind the power converter which is in front under the locker/3-Fridge option. So if you have a 3-way or the newer large AC/DC fridge, you access as above by removing the drawer (or power converter on early TaBs).

But, if you want to access the black tank flushing line check valve, you need to remove the washroom sink unit to get to it as shown in my photo above in previous post. Good luck finding your leaks.
Cheers

88keys · June 2022

Yea, it's only happening when using black tank flush. Checked everything else and no leaks elsewhere, other than at front of wheel well. Thanks for the info on drawers and cubby, I'll go try again. Figure I'll check where you found your leak first.... If not, I'll move onto check valve. From the outside, the area the water comes out at wheel well is to right of bathroom window which puts it in line with sink area.... And check valve. Uggh
Thanks everyone!

Denny16 · June 2022

My guess, is the check valve is the cause of the leak. When you use the blank tank flush, is water going into the black tank? You can check this by looking in the toilet to see if water is coming in from the jets.
Cheers

88keys · June 2022

Yes, there is water going into black tank and coming out sewer hose.... And at the same time front of wheel well. I agree, think it is probably check valve.

qhumberd · June 2022

Here is another view of the black tank flush valve plumbing in my 2019 400. I exposed this by removing just a few screws for the fold down sink (mine was the older round one) White hoses on R are rising up to the check valve

Image: https://us.v-cdn.net/5021717/uploads/editor/cm/nq8dl2ggmz25.jpg

Image: https://us.v-cdn.net/5021717/uploads/editor/tv/yrk5ftn2xavw.jpg

Image: https://us.v-cdn.net/5021717/uploads/editor/qc/w6l3sg67yfrs.jpg

Denny16 · June 2022

88keys said:

Yes, there is water going into black tank and coming out sewer hose.... And at the same time front of wheel well. I agree, think it is probably check valve.

Good, then the check valve is connected the right way round. How old is your TaB? If it is still under warranty, I would get a TaB dealer service dept, to check this out. Taking the sink unit out, is not an easy task.
Cheers

88keys · June 2022

Appreciate it, it's a 2021, a little bit of warranty left. I'll contact dealer.

stmur7 · June 2022

Thanks so much to everyone. It does sound like the check valve. I will be working on this today, and I will get back with my findings. I will say I have found a number of loose connections. I found glycol around that tank and they cap was loose. It feels like they through things together and were not thorough assembling the Tab.

stmur7 · June 2022

OK. So I removed the panel that was below the sink and turned the black water flush on. The leak was pouring down from behind the whole sink panel. I removed all screws to take of the sink but there are 2 right behind where the sink rotates up and down that I can't get to. It's a #1 square screw but they put it in a spot that no screw driver can fit. Hard to believe they put the screws in that spot. I'm not sure how to get to them. Seems i need some kind of really small right angle type of screw driver that takes up almost no length coming off the screw. If anyone knows what I mean, please let me know how you did it or what you used. I will say I am thankful to you folks who helped me with this. It looks like it is that check valve if it's up higher above the sink behind the panel. Why it goes up there for a blackwater flush is a whole other question.

mjwaldner · June 2022

I think it needs to be up above the black tank high enough to keep the water from the black tank from back feeding. Just another safety precaution in case the check valve fails.
As for the screw. I have not removed my sink yet. But remember that they put the campers together from the inside out. So the outside walls are one of the last things to go on.
This is my go-to solution for tight spots. Not sure if it will work for you.

Image: https://us.v-cdn.net/5021717/uploads/editor/wt/4xuxp7irorof.jpg

stmur7 · June 2022

I think that is what I need. It looks small enough to fit in there. Thanks so much! I want to say I also found a small slight leak under the bed right where the black flush enters. But the other one just absolutely pours out behind the sink. They obviously are in a big hurry putting these things together. I wonder if it's the same guy doing it. Heh.

manyman297 · June 2022

stmur7 said:

Thanks so much to everyone. It does sound like the check valve. I will be working on this today, and I will get back with my findings. I will say I have found a number of loose connections. I found glycol around that tank and they cap was loose. It feels like they through things together and were not thorough assembling the Tab.

Yeah. Other connections to check are:

ALL connections on the back of the nautilus panel
Drain connections under kitchen sink

I think the cap on the glycol reservoir is meant to not be tightened completely for some reason. If you try and tighten it, it will just loosen again.

stmur7 · June 2022

Thanks. Still having trouble getting the screws behind the sink. No room to turn anything or get leverage. I feel like I need some kind of small electric right angle screwdriver.

qhumberd · June 2022

@88keys and @mjwaldner your leaks around the black tank flush system makes me wonder if your flush systems were in locations where freezing could have damaged the fittings or the check valve? This area of plumbing is not in any winterizing protocols that I have read. I have added a low pressure blowout to this system when winterizing as a precaution.

Howdy, Stranger!

Quick Links

Categories

Tab 400 BD Black Tank Flush leak

Comments

2019 T@B400 Boondock Lite "Todd"

2019 T@B400 Boondock Lite "Todd"