Back in June of 2020, I noticed dripping from the belly pan on the trailer. Upon further inspection, it was coming from where the black and grey tanks join before the sewer hose connector. In conjunction with this, the black valve was becoming increasingly difficult to close and sometimes would not close completely! The drip was obviously not any type of clean water but also a bit smellier than the grey tank, seemed like black water.

I contacted Vinnie of Vinnie’s Airstream Repair to get his take and to see if he might have an opening in October/November (like that would happen). He responded back suspecting it was the Calder coupler, a rubber connector to allow flexing in the assembly:

I put up with the leak for a while, sometimes it was copious but at times it was almost non-existent. The black valve would close completely at times but I could also get a surprise taking off the sewer cap!

When we got to Grants Pass in September, I thought I would tackle trying to fix the valve not closing. The suspicion was some toilet paper stuck in the valve. I looked at many solutions, where I didn’t have to do any trailer work. I purchased this valve:

I can attach this to the sewer output with a elbow connector that shoots water back into the tank. By closing this, it allows me to fill up the black tank (or grey) with water. Theoretically, this should allow water to fill the tank to a level that covers the internal valve. This should also help anything stuck in the valve to release and float away. This is how I set it up:

I think it may have helped a little bit. I could really slam the valve handle and it seemed to shut completely but it still leaked out the pipe. I resolved myself to see what was REALLY going on when we returned to California for the holidays.

Fast forward to the holidays, I pulled the trailer with the curbside on the curb and a 4 lego block on the other to give myself ample room. I saw the leak up close:

I removed the panels on the pan to get a better look:

I could now see exactly where the leak was coming from (the black valve):

This means the valve needs to be repaired or replaced. I opted for replacement. I ordered all the needed parts. One part I was unsure of was how the valve attaches to the black tank:

The valve is made of 3 parts, valve flanges on either side and the slide valve in the middle. The valve flange on the black tank slides inside the black tank opening and is tightened with a hose clamp. If you refer to the first image I posted here, I have to replace all the parts encircled in red.

I contacted Vinnie with the newfound information and laid out my plan. He graciously called me back and discussed the repair and gave me tips on what to watch out for. Armed with that knowledge, and tips, I was emboldened to try the repair. However, being the way that I am, I waited about another 3 weeks to cogitate a bit more, and get up the courage to perform intestinal surgery on our trailer.

The removal was a bit more difficult than I thought it would be. Airstream installs these components while the frame is upside down but we have to fix them while WE are upside down. I had to completely cut through the Calder coupler, which was OK as I had a replacement. I also had to cut through the sewer outpipe.

Since I had to physically glue one of the valve flanges to the Y connector, I wanted to ensure that it was at the right angle as the old one:

Notice the yellow circle, which will come into play a bit later. The shaft on the valve is threaded but has a hole drilled into it. That is where the shaft extension attaches. One of the Vinnie tricks was to silicone the gasket on the valve flange before installation. This keeps them in place when you try to sandwich everything together.

Next, I cleaned up the black tank outlet, this is where the other valve flange goes. It is a snug fit but not watertight (or some other fluid). The clamp helps, but the Vinnie trick was to use plumbers putty between the outlet and the flange.

Time to put in the Y assembly that has the black valve flange attached and also the rubber connector for the grey tank. When putting this in, you have to slide the middle valve component between the valve flanges that are on either side. This is WHY you want those gaskets attached tightly. It took a few attempts and some further modifications to the pan.

Above is the new black valve assembly, all three pieces together. It fit well, the real pain is trying to get to the two bolts and nuts on the top part of the valve. Took a lot of time, patience, and a few choice words!

Above is the grey tank connection to the Y connector. This is the new rubber connector. It required some shortening to fit well.

Above is the output of the Y connection, this is where all the waste will come out. This is before adding the extension where the sewer hose attaches. this also shows another Vinnie trick. He recommended cutting the pan up high enough so you can easily get the Y connection in. Worked great.

Now to re-attach the dump handle extension. Here is a picture of the valve connection peeking out of the pan. It is shorter than the original. The second picture shows the attachment point. Compare that to the previous picture where the original valve had a threaded shaft with a hole drilled.

This difference required me to change the bracket that holds the extension and move it a bit more inboard. It was only three rivets so it wasn’t too bad. Here is the finished ‘product’:

I did a post-mortem inspection on the black dump valve. It was in such bad shape, the flange broke apart when I tried to remove it from the black tank (1st picture). The second picture shows both the ‘item’ that stopped the valve from closing and also shows the part that facilitated the leaking:

But the proof is in the pudding, as they say. Initially, there were no leaks! A week later there was no leakage from the valve or when I opened the pipe. Very good.

Now, I have to find the water leak <sigh>.