My continuing black tank saga.

[urnmor]

As many of you know I have been having problems with my black tank valve not closing all the way. So over the last few days I have been backflushing the H--- out of it with one of those after market back flusher. So today before I left the campsite I pumped out once again but this time I forgot to open the valve before filling the blackwater tank. I was inside the trailer when I heard a pop. I ran outside and noticed two things first the blackwater valve was in a closed position and secondley clear water was leaking from the right and left corner of the tank. When I checked I noticed that there were two small holes that apparently popped when the pressure got to be to much. Has this ever happen to anyone else and if so how would I fix it.

As to the valve it still will not close all the way.

[CRH]

Is your tank leaking from holes in it? Or is your belly pan leaking from water coming from a valve problem?.....I hope it is the latter...Your tank is polypropylene. Next to nothing will stick to it. You may be able to weld the holes shut with a plastic welder.

[ventport]

Is it possible that the holes are where the tank monitors should be screwed into? Maybe they were loose and the pressure popped them out.

[dbj216]

Black tank blues. I suspect the black tank dump valve won't close all the way due to a clog. The valve is most likely a "blade" style valve that slides in two grooves, think guillotine. If the valve is closed just when a piece of paper is floating by, it can keep the blade from closing. If your grandkids dropped their rubber ducky in the toilet, that can jam a valve too. Other reasons for not closing all the way is a rod that is adjusted too short, or a seal that has gotten out of place.

I will submit your black tank is fully capable of handling the absolutely full condition. I can't imagine a polyethylene tank rupturing due to overfilling, unless it was molded too thin or has some molding defect. If you overfill the tank, the water flows into the toilet, or up the vent pipe. The black tank is vented. I don't understand how pressure can build up in it.

We used to take polyethylene tanks, fill them with water, and drop them off the factory roof two stories onto the parking lot. Bombs away, bang. They would dent, but not rupture. It gave us engineers something to do. Polyethylene is strong stuff. Cross linked polyethylene is even stronger.

Dripping water doesn't necessarily mean a ruptured tank. I have a plumbing leak over my freshwater tank that appears as a leaking tank, but it ain't. I know because when I drain the freshwater plumbing, no pressure in it, the dripping stops with a completely full freshwater tank.

I can not see any of the water tanks under my 86 or 66 Airstreams due to the tank pans covering them up so they can be heated. Is your tank cover removed so you can see the actual place of the leak? If it isn't, then it will be in order to fix or replace the valve that won't close.

I guess I would like to help diagnose the leak problem, but need some more information. You mention you forgot to open the valve when flushing the tank. What valve? I assume it is the black valve in question. So all that happens is you get a full black tank. There shouldn't be any pops.

This is an interesting "who done it".

David

[urnmor]

Is it possible that the holes are where the tank monitors should be screwed into? Maybe they were loose and the pressure popped them out.

I never thought of that however I suspect you are right. The holes are the same size and in the same spot just on opposite sides of the tank.

need some more information. You mention you forgot to open the valve when flushing the tank. What valve? I assume it is the black valve in question. So all that happens is you get a full black tank. There shouldn't be any pops.

It is the black tank valve I failed to open. Unfortunately there was a pop and as previously mentioned it may very well be where the monitors are as the holes are in the same place just the opposite corners,

I spent hours and numerous back flushes trying to clean the tank. Everything is now running clean except the valy won't close all the way. I now have to assume it is the seal.

will call the dealer to see what they have to say.

[crispyboy]

Is there an inspection plate under the valve area?
Over the summer I had to cut a hole in the tank pan and to replace the flange between the valve and the tank. While there I went ahead and put new parts in the valve. The valves are easy to rebuild. If your handy give it a try.

[JPAS]

If the holes are in the tank pan, these may be intentional drain holes to keep the tank pan from holding water in case of a leak. the stuck valve could be a number of things. is there any way that you could post a picture of these drain holes and maybe of your dump valve?

[urnmor]

I spoke to the dealer and I was told the holes were for drainage. As to the value not closing all the way. It appears to be closing sufficiently to prevent any thing from entering the dump tube until after I have everything hooked up. So for now I am going to leave as is and see what happens the next time we camp in November.

[CRH]

I wouldn't leave it....It sounds like the liquids are draining out and leaving the solids to lay in the bottom of your tank. After a while, the crap will be concrete.

[dbj216]

Sounds like urnmor has thoroughly flushed and drained the black tank. He heard a "pop" and then noticed water out the drain holes. We don't know what the "pop" was. It may not have been related to filling the black tank to capacity.

I remember testing my new fridge on gas for the first time. I heard it ignite and decided to run it and see if it would cool. Then I heard a loud "bang". Scared the heck out of me. I could only think of a gas explosion. Turns out it was the next door neighbor boy with a firecracker.

Sometimes noises are not what we think they are.

So urnmor, try this test. Close your black valve. Leave the cap off so you can see if it is leaking out the sewer hook up pipe. Put a bucket or pan under it to catch any leaking water. Now fill your black tank to 80% or more with fresh water. Look for leaking out the sewer pipe. Leave it all night. Make sure your gray tank is empty. If there is water leaking out, then you know your black tank valve is leaking. Knowledge is power. You will know if it is leaking or not, and you will know how much; a slow drip or a gallon an hour.

David

[CRH]

When tracking down my leaking valves, I put two different colors of food coloring in the water I put in my tanks.

[thiel]

Originally Posted by CRH

When tracking down my leaking valves, I put two different colors of food coloring in the water I put in my tanks.

That's a good idea right there ...

[GMFL]

Take the gate closer out and replace. Only cost a few buck and you are fixed. 4 bolts hold valve inline sides right out and new slides right in. May not even need to replace if you can clean once in hand

[Ray Eklund]

GMFL's option is very practical, but has some caveats.

-There are only four bolts to remove.

-When the bolts are removed, you need some 'slop' to remove the three piece system. If no slop, you could damage the pvc coming out from the black water tank, or break the caulk seal.

The 'sandwich' three parts just does not slide out as a unit, it fits into the pvc on the left and right sides.

This system is very tight and not flexible. Obviously installed as independent units at the factory by caulking into the Black and Grey Water tanks to attach, and the outside bracket to prevent the entire system from flopping up and down while moving.

-There are two fitted rubber gaskets. One on each side of the 'paddle' that slides open and to close. You will find that you will have to take a toothbrush and scrub fine sediment out of the plastic end camps, both gaskets and the groove that the paddle slides back and forth to open and close.

-When you reinstall, to make sure you did not disturb the rubber gaskets that seal the black water flow with the sliding paddle. If a gasket is not seated, you will know by the sliding paddle hanging up... usually on the last part of closing and sealing black water flow. You might have to just align the end caps and the sliding paddle again, rather than ruining your rubber gaskets which are formed special to this unit.

IF you try to muscle the sliding unit OUT... you could create a leak from the Black Water tank into the PVC that is connected to the Black Water dump sliding valve handle.

How did I learn this? I discovered a poor job connecting the black water tank to the pvc connected to the black water valve. The round clamp to add compression to the black rubbery sealer misshaped the black water tank outlet, so someone did a fast repair at Jackson Center... as I purchased the trailer new.

You will also notice 'calcite' attached to the surfaces of the Black Water Tank. White crusty material that your finger nail can remove. It was just scattered lightly, but if you leave fresh water from flushing the system, the water could evaporate and leave mineral residue. This could also jam up your sliding paddle if you use hard water in your fresh water tank.

It did take some prep work to clean surfaces of 'caliche' buildup, then some fine steel wool to give myself clean surfaces for caulk. Some wiping with Acetone to prepare the surface of black water tank and pvc connection to the tank.

The sliding valve works smooth, as it did before having to remove.
I added five gallons of fresh water and NO leak from the bad caulk seal.

Do I want to go through all of this again? Not if I can help it, but could do it in much less time now knowing what to do or expect.

I hope this helps. This was on my 25 foot 2014.

[Tater]

For those who have removed or repaired the valve. Did you have to cut into the metal cover where the valve on my 12 classic is located?

[dbj216]

Thanks Ray for your excellent description of all the trouble a guy can get into by just removing 4 bolts on the dump valve sandwich.

For my trailer, the biggest job is getting access to the dump valves. I removed the tank cover "pan", rusted and broken bolts and all. It is silly to me Airstream engineers did not figure out an access hatch for these problematic valves.

Yes, many Airstreamers have cut the tank cover pan to gain access to the dump valves to fix a present problem and future problems. I would prefer to do this with the tank cover pan down so I wouldn't cut the tanks. I'm not a surgeon.

I'm now removing the fresh water tank in my 86 as I have a plumbing leak below the floor but on top of the tank. The galley sink hot / cold lines and the 12v pump line run under the floor to the street side bath and street side city water inlet. Big job to fix a little leak. I bet Jackson Center or experienced dealer techs have an easier way to do this.

David

[CRH]

I cut a access hole in my belly pan. I started by drilling a small hole and using tin snips to cut a littlie bigger hole so I could see where the tanks where laying. I used a set of electric shears to cut a larger access hole. After I swapped valves. I cut a cover panel out of an old street sign from the recyclers.

My valve swap job took me one day. That included running to the hardware store to buy pipe. I also spent a lot of time dragging this tool and that tool out trying to find what worked best. Now with an access panel, I could problem swap in a new set of valves in an hour or two.

[dbj216]

That's what should have been on our trailers in the first place. Someday I will wish I had done the same thing.

I did do it that way on my 66 Trade Wind. I made a removable aluminum "box" around the valves that is easily removed. It is insulated and benefits from the heat I dump into the waste water tank cavity when the furnace is running. I can clean or replace valves on that trailer much easier.

David

[Ray Eklund]

My LAST post on Dump Valves...

If you are willing to take a look, remove the dump cap that hangs by a small cord.

Take a flash light and LOOK at your dump valve. My 2014 25 foot International I can see most of the movable dump valve and the 'neoprene' rubbery gasket that seals on the outside part. If you can open the valve, more can be seen.

If you have black water still in the tank, you may want to be a bit more... careful trying to pull the valve bar to open it. You may need more than a paper towel...

The smaller grey water side is harder to see the dump valve, but you may have a small mirror to see the rubbery gasket and if it is seated.

We may be able to debate the issue if you should leave some fresh water in both sides to prevent any sediments from drying hard... or flush well directly at these valves with a low pressure hose.

Access appears easy and simple. It is not. The gaskets can drop out of their inset seating and jam up the sliding valve, when trying to line the three pieces up to finish the job with the four bolts. Being impatient will just create more problems. Before tightening the four bolts snug, make sure the sliding valve is operating, smoothly.

IF you get resistance in movement, stop and try to get an actual look. Something is not aligned.

THE END of my plumbing participation and extent of my knowledge.