Friday, October 24, 2014


In Part 1 of this series, I described the separation that had occurred between the grey water tank and its lines on our 2007 Airstream Interstate mid-bath motorhome.  I'll now describe how we dismounted our tank so that we could repair that plumbing, and I will also include some peripheral rehab in this post before proceeding to the main retrofit and re-install in the next post.

Please see BIG FAT DISCLAIMER regarding DIY safety.  Also please realize that not every Interstate is configured identically - even if they are the same model and same year, they may have been built with different options, causing alterations in equipment placement.  None of this procedure given below has been approved or endorsed by Airstream.  Prior to beginning this work, my husband called Airstream technical support and asked if there was a service bulletin on how to repair this problem, and he was told that there was not.

You should realize in advance that, if your grey water system proves to be constructed like ours, then it was a permanent install never intended for removal (an exceptionally poor design).  If your three lines have already sheared off the tank as ours had, that's a moot point.  But if one or more of your lines are still attached, you will shatter your remaining connection(s) by removing your tank.  It's a one-way trip into Repairsville from that point - you won't be able to re-install the tank as it was.  

Step 1:  Make sure your gray water tank is empty of all water.  It's heavy when full or partially full, and you don't want it to come crashing down on your skull.

Step 2:  Download a copy of Airstream's "Interstate Motorhome Parts Book" for your model year (if that link does not work, go to the Library of All Things Airstream start page).  Familiarize yourself with your system lay-out, which might look something like this:
The bottom photo shows a view of the tank removed from the vehicle, angle similar to line drawing but rotated upward.
Step 3:  Drop the "heat shield" described in Part 1 by removing the three nuts on the vertical all-threads (red circles above) and unscrewing the bolt at location 1,6,4 in the diagram above.

Step 4:  Disconnect the water level sensor, which in our case was an old-style telephone line plug.

Step 5:  Cut the heating pad wire bundle.  Shame that this thing had to be hard-wired instead of incorporating a plug, but it can be repaired later.

Step 6:  Detach the fitting that connects to the dump valve.  Ours was a square-end connector with screws in it.

Step 7:  Locate the steel brackets that attach the tank to the chassis.  If your Interstate is like ours, they might be showing considerable rust (discussed below).  Release each and remove the tank.

Here are a few photos showing our tank and some of the prep work we did on the shield and brackets prior to tackling the challenge of retrofitting the tank itself.  The plumbing retrofit and re-installation will come in the next blog post.
This is the removed tank nested in its "heat shield" (which is lined with pink insulating foam), both sitting on the ground.  This orientation is the same as it would have been if I had been facing the port side of the vehicle with the tank still installed on the underside of the vehicle.  You can see that the tank was very dirty on top because grey water had been spilling out over it instead of being delivered to the inside of the tank as the design intended.     
One of the first things I did was to scrub the entire tank clean, because it was gross.  I also flushed the inside of it with clean water.  That plastic wrap you see around the line at the bottom of the photo was my attempt to keep water from getting into the severed heating pad line.  

By word of mouth I was told that these tanks can be replaced for about $350.  However, as I noted in Part 1 of this post, this system had been so poorly engineered to start with that we were worried about the efficacy of conventional repairs.  Therefore we decided to try DIY.  Besides, nothing seemed wrong with the tank itself.  Just the way in which it had been plumbed.   
Tank markings, just so you can compare to your own.  
Alien hieroglyphics??
Close-up of heating pad info.  
Heat shield, with one of the main tank support brackets visible at upper left of center (square U-shaped metal piece). 
This heat shield is made of an inexpensive sheet metal tack-welded together.  It appeared to have had some kind of a surface coating that had degraded considerably.  Given that we had gone to all the trouble to drop this thing, I felt some rehab was in order here.  The old material sanded off easily using a medium-grit paper (be sure to use respiratory protection - this sanding process creates an airborne mess, and you will need a shower afterward).  
Sanding completed.  
I see no need to spend extra money on this kind of a mini-job. We do a lot of DIY and have plenty of old paint left hanging around from other projects, so I just used some of whatever we had available.  
Newly-coated shield exterior.  
This quarter-inch foam on the inside of the shield... I wanted to remove that and also re-coat the inside of the shield, which had receive a lot of the grey water leakage.  However, as of this blog post, I was having trouble finding a replacement source of this foam (I can buy it, but not in sufficiently-small quantities).  We may do that part in a future effort. 
Art shot, close-up of one of the heavily-corroded support brackets.  Why would Airstream put its iconic (and resurging) reputation on the line by producing this high-end Interstate, which was a six-figure vehicle when sold in 2007, and then use such crummy quality in some of the parts??  What did they save by using a cheap grade of steel in these support brackets? A buck or two?  Penny wise pound foolish because then, a few short years later, someone writes a blog post calling attention to these questionable decisions.  I just don't understand that kind of mentality.  Do it right the first time so that DIYers don't have to re-do it later!!

Similar situation with the all-thread down-rods that support the shield.  My husband replaced those with stainless steel because the originals had corroded.  
We blasted, ground, sanded, coated, and otherwise rehabbed all the support brackets for the grey tank system so that corrosion would no longer occur.  Here you see this black one re-installed at photo center.  The orange thing you see toward the bottom of the photo is the fiberglass underside of the port side running board, which I will discuss in a separate post.    
Stay tuned for Part 3 in which a troublesome tank is retrofitted with rubber boots and re-installed.
Devotion to DIY, in our case.

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