Black water tank leak?

[DennisPLee]

Recently while draining and flushing the black water tank on our 2018 Flying Cloud 25FB, I head a “pop” sound like a hose or fitting coming loose. I stopped flushing the tank and immediately saw water dripping from the small holes in the corner of the metal belly pan. A day later after the water had dried, I refilled the blackwater tank with about 5 gallons of water, no leak observed. I checked the brass anti-siphon valve inside and did not see any loose connections. Any suggestions on what may have come loose before I drop the belly pan for inspection?

[mstemler]

I too have developed a leak on my ‘05 International CCD black tank.
More precisely the flush line for washing the black tank. Suspect fittings leaking.
How do I access the line in?
(Symptoms: water at the interior rear floor under the office desk
And a second time exterior leak showed at rear bumper, higher than the tank.)

[DennisPLee]

We recently had a Micro-air Easy Start installed on our air conditioner by Vinnie Lamica at North Bay Airstream. This gave me the opportunity to speak to him about the leak from the small hole in the metal pan I experienced when draining the black water tank. Mr. Lamica indicated the underneath portions of Airstream travel trailers are constructed upside down and recommended against removing the metal tank pan to locate and repair the leak. He did not indicate there were any brackets or straps to hold the tanks in place when the plan is removed. To do any repair, he would drain the tanks and cut a hole in the metal pan to access the blackwater and greywater ABS drains and knife valves. This appears to be a common way to access the valves and manifold and I suspect the blackwater tank flush lines too.

Vinnie pointed out there are several connections to all the tanks. He described one common problem specifically with our Flying Cloud 25FB model and showed me the issue on a new freshwater tank he had in his shop. When the fresh water tank is full during travel, the sloshing water can place strain on a small outlet attached to the tank near the bottom that goes to the tank drain located on the bottom of the unit. This strain may eventually lead to a stress crack where the fitting is attached to the tank. He recommended not traveling with a full freshwater tank to reduce the potential for this connection to crack and leak.

While this information may not be helpful in addressing your specific problem, like myself, you may not be able to effect repairs yourself. We scheduled another visit to Vinnies North Bay Airstream repair.

Dennis

[mstemler]

Thanks. So appreciate your share. Hard to visualize that many gals. of waste in the tank supported simply by galvanized cover.
But your post helps me avoid a bad decision. Don’t remove the cover to access the tank! We tested the tank and at half full the leak doesn’t reappear. The leak must be above half full.
Some older posts suggest just not using the flush port and for now that’s what we will try.
Still I’d love to see a picture of the flush water location into the tank. If we are ever to repair this it is essential to know where to search. Good to know the caution on full tank transporting of water. Anyone else had this advice?
Any solution? Sounds like in this prob the drain at bottom of tank was the culprit.
If you get it solved Dennis let me know what you find out. ☺️

[DennisPLee]

I have crawled under my unit and looked at the tank pan several times contemplating removal. There are a number of bolts around the pan that would have to be removed. Vinnie at North Bay Airstream Repair indicated if the pan was removed only the various connections would hold it in place. The cut and repair the pan method to access knife valves, tanks and other connections seems to be archaic but I see it is a common recommendation including how the Airstream factory does it.

I have done a number of fill and drain tests trying to determine where my leak comes from, still not sure since I cannot see any of the connections, only know when it happens. Looking at the Airstream parts schematics it appears there are different tank configurations and connections depending on model. And all the connections are not fully illustrated. If your problem is with the freshwater flush system, there are other methods to flush the tank as you indicated.

It was suggested the freshwater tank drain connection leak (ours is not leaking) issue is with the Flying Cloud 25 FB model. Vinnie had two new tanks on hand as replacements for this model.

[boatdreamer]

Dennis did you ever find out what was causing your leak? The reason I’m asking is I was doing the same thing on our 2017 26U and heard the same pop as you then water started dripping out of the corners of the tank pan. I’ve read several threads about cutting an access hole under the valves but I’m scared I’ll hit a tank or any wiring that might be there. Looking at the parts manual it looks like there’s a rubber coupler (Calder coupler) that might have slipped off or has a hole in it. Any information will be greatly appreciated because this is our home for the next 3 months as we are between selling and buying a new home. If I can’t find a solution by Monday I’ll be taking it to Airstream of Tampa and we’ll be in a hotel until it’s fixed.

[BayouBiker]

A common leak point that can also reseal is the dump line. It has a butyl rubber putty similar to chewing gum that does not harden and could have unsealed and then resealed.

Another possibility is that a lower vent stack seal came loose, if you happen to have overfilled while flushing. if the vent stack is intact and the toilet seal is clean and tight, it is possible to fill the black tank and have it overflow onto the roof without any other leak points.

The tanks do have straps in addition to the pans holding them in place.

[GCinSC2]

Originally Posted by boatdreamer

Dennis did you ever find out what was causing your leak? The reason I’m asking is I was doing the same thing on our 2017 26U and heard the same pop as you then water started dripping out of the corners of the tank pan. I’ve read several threads about cutting an access hole under the valves but I’m scared I’ll hit a tank or any wiring that might be there. Looking at the parts manual it looks like there’s a rubber coupler (Calder coupler) that might have slipped off or has a hole in it. Any information will be greatly appreciated because this is our home for the next 3 months as we are between selling and buying a new home. If I can’t find a solution by Monday I’ll be taking it to Airstream of Tampa and we’ll be in a hotel until it’s fixed.

If you're handy with tools and able to get the rear or the AS elevated a bit for access it can be a DIY project I just finished a pre emergence valve R&R on my 2007 Classic.

YES you can hit good parts while cutting the access panel. Drain pipes, fittings, tanks and sending unit cables.

Mark first, cut last. Your parts manual has a good layout of the plumbing it helps visualize the system. You can see a bit by looking in along side the rubber slits these are secured via double faced tape. Remove if you wish and replace later. And having a valve for a size and layout guide helps too. Try to make a layout on the pan of the plumbing layout. Use that as a cutting guide. I made my cuts with aviation snips, not the easiest but does make it cut slow and observe to avoid stuff. Better tool likely is power snips. I'd also make the cut outside of the tank profile to avoid tank contact with any tools. File edges and cover edge with masking tape, my bandaid count was zero. Making a full size access panel gives you access to the no fuss flush, sending units, spider webs all the good stuff. And that caulder coupler loosening it can be a help in R&R just creates more options for install etc.

Gary

[DennisPLee]

After cutting a square hole in the belly pan using a circular saw and metal diamond blade I was able to access the manifold from the grey and black water tanks and also both knife valves. I was careful through inspection to make sure I did not cut into one of the tanks. I kept the blade depth at a minimum and there is about 1/2 inch of insulation between the pan and tank. BTW, Airstream says the tanks are held in place with straps.

After removing the cut piece, it was easy to observe that the rubber pipe connection between the grey water tank and PVC “Y” manifold had come disconnected (the pop sound) causing the leak. It was easy to reattach the fitting and tightened the pipe clamps. I purchased a similar metal sheet, cut it to fit over the hole, attached it with metal screws making sure none hit a tank, and sealed it with duck tape. Cutting the hole was the hard part, reattaching the fitting took less than 5 minutes.

[boatdreamer]

Thanks to all that responded. I did the same thing Dennis did. I cut a 1” hole and used my new Harbor Freight borescope to make sure I wasn’t going to hit anything important. I used sheet metal cutters and made to hole large enough to inspect everything. I found the same thing as Dennis, the rubber coupler had just slipped off and took five minute fix. I ordered a new coupler because mine was showing signs of cracking so I’ll replace it before I make my access door. Lesson learned but I did get some new tools out of the deal!

[s1000pre]

One of the items on my list when I took my 25FB into service last week was the same leak as described. It leaked from the 3 forward driver side holes on the bottom of the tank pan...only when flushing. Unfortunately my dealer did I not provide any warnings of issues dropping the pans. To my knowledge, they dropped the pan/tanks and found no leaks or loose connections ��. So, what are the possible ramifications of them dropping the pan and tanks?

[mstemler]

This may be a side point to your issue but in my case the leak we developed while flushing the black tank may have been due to excessive water pressure from the campground flush hose. Since then purchased a hose threaded brass pressure regulator so nothing else pops!
In my case we found the leak appears when using the flush connection. No more using the black tank flush port.
I learned a lesson I’ll apply to all future pressurized in coming water hook ups. I think not turning off pump while hooked to city water may lead to excess h20 pressure.

[boatdreamer]

Here’s the details of what I did to cause my leak. We’re staying at a campground that doesn’t have a sewer hookup so I bought a 27 gallon waste tote. Unfortunately the Airstream sits too low to drain the waste water into the tote. I bought a FloJet RV waste water pump, now I could pump uphill into the tote sitting in the bed of my truck. Here’s where my problem began. After attaching the FowJet to the waste water tube I opened the black water and started the pump, I did the same with the gray water and all was well. After both valves were closed I attached a fresh water hose to the pump to flush out the pump and the hose, turned on the water then the pump and that’s when I broke our Airstream. I heard the pop and water was coming from all four corners of the tank pan, then the panic started. At that point in had no clue what I had done so off to the parts manual to get an idea of how the plumbing system works. Turning on the water built up pressure in the dump tube and popped of the coupler. When I saw the rubber coupler I was hoping that acted like a fuse by either slipping off (which it did) or it had a hole in it. The tank pan was the next issue. I talked to a friend and he suggested drilling a 1” hole close to the dump tube and start cutting from there, but then I thought this gives me a reason to buy a borescope to look around before cutting anything. This gave me the confidence to cut a 10”x10” access hole that Airstream should have done from the factory but didn’t so now I have access to all things to do with waste water. I have covered the hole temporarily until we get home then I’ll make a cover with thumb screws for future access. I hope my mistake keeps someone from having this happen to them.