In the Airstream universe you will find a curious phenomenon: passionate debates about caulk.  That’s because the constant movement of all parts on the road causes all travel trailers to leak eventually, and a good caulk is our first line of defense against rain penetration.  Rather unfairly, Airstreamers get more of this debate than owners of other brands, mostly because Airstreams have been around for so long, and so many of them remain on the roads after decades of use.

An Airstream might easily be re-caulked a dozen times over its lifetime.  In contrast, “disposable” cheap travel trailers tend to get chucked into a landfill when they start to leak because they’re starting to fall apart too. You don’t hear the owners of those talking quite so much about re-caulking. They’re busy re-financing.

Another reason Airstreamers love to talk caulk is the aluminum construction of an Airstream.  Silicone caulks don’t adhere as well to aluminum, so we tend to go for polyurethane caulks that are more expensive but stick like crazy and stay gooey for a long time. But what caulk is the “best”?

For decades, the gold standard of caulk for silver trailers was some gray stuff called Vulkem.  These days Vulkem is just a brand name, applied to various formulations of polyurethane caulk made by Tremco.  I use Vulkem 116 but you can also get TremPro 635 from the same manufacturer, and a few variants. Either way, it’s great stuff.  It’s sticky like hot salt-water taffy and adheres to aluminum like glue, once cured it flexes a lot without breaking its seal, and it’s designed for exterior use (only) so it’s UV-resistant and completely waterproof.

Finding the stuff is the problem.  Lots of online sellers offer it but since a tube is anywhere from $6-14 and shipping tends to add $7-9, you want to get it locally or combine it with another order to duck the shipping charge.  Locally it’s sometimes available through Home Depot or Fastenal, but here I couldn’t find it stocked anywhere so I had to order it.

You can always go to the local RV store and find products that claim to be roof caulk.  I’ve tried a few and had uniformly disappointing results, especially the “self-leveling” type.  Those RV-store caulks seem to be made for the disposable RV market, because they all break down in a few years under sunlight and start to crack, then leak.  You can go on the roof of my Airstream and see what things (vents, antennas, etc.) have been caulked with the standard products; they’re drying out and starting to crack around the edges.  I will have to go up on the roof sometime, scrape all that stuff off, and re-caulk.  It’s not a job I’m looking forward to.

You can also see the things that were caulked with Vulkem or TremPro.  They’re still soft and pliable, even sticky, after years of UV exposure.  When I removed the old cellular antenna a couple of weeks ago, the caulk exposed to the UV was hardened but intact, and still waterproof. Around the base of the antenna the caulk was still gooey.  Think about that: the antenna was installed in 2005 and the caulk on it stuck to my fingers like fresh glue after eight years!  I’ve got it sitting here on my desk, just because I like to pick it up and marvel at it once in a while.  (Yes, that’s super-geeky but hey, it inspired this blog you’re reading.)

And eight years is nothing.  I’ve taken apart sections of my 1968 Caravel and found Vulkem contained inside joints and seams that was still good.   That Vulkem was probably decades old.

So that explains why I was willing to wait a week to get a tube of Vulkem 116 from an online seller. I used it to seal up the antenna hole for the cellular Internet booster.  The hole was 3/4″ and the cable was only 1/4″ so I used a set of rubber grommets to fill in the gap, plus a 2″ tall rubber “boot” that I found at Ace Hardware.  This formed a small tower on the roof, from which the new antenna cable emerges. Then I caulked the beejeebers out of the whole thing, sealing it completely.

Two days later, the caulk still feels like it was fresh from the tube, and since it cures very slowly (just 1/16″ of an inch per day at 75 degrees F & 50% humidity) I expect it will take at least a week due to our low humidity.  Fortunately, the Airstream isn’t going anywhere for four weeks.  I’ll get back on the roof in late May to check on the antenna cable again, after having towed the Airstream 2,000 miles to Ohio, just to confirm that the seal is flexing appropriately at highway speed and not developing any gaps that could cause a leak. I’m pretty sure it will be fine.

There are a few challenges with using this stuff.  First off, the fumes are stinky and toxic, which may be why it’s not approved for indoor use.  I would not use this in a workshop without having windows open and a fan.  Second, it’s trickier to shape and smooth than silicone caulk, because it sticks to everything.  The old “wet finger” trick that you use with silicone won’t work—it’ll stick to your wet finger.  I strongly suggest wearing disposable vinyl gloves when you work with it, and bringing along a bunch of paper towels for cleanup.

Third, saving the leftover tube is a bit of a pain.  It’s hard enough to obtain that you don’t want to lose the leftovers between jobs.  Some people put it in the freezer, which I think is a bad idea because the smell of the caulk can ruin your food, even through a plastic bag.  I like my ice cream to taste like Oreo Mint, not vanilla Vulkem.

We’re trying an experiment instead.  We wrapped the nozzle in plastic kitchen wrap, and then vacuum sealed the entire tube with Eleanor’s Food Saver.  (Eleanor wants me to mention that this was her brilliant idea, and I’m glad to do so.  If I open the tube in a year and find it congealed then it will be Eleanor’s terrible idea.  But it should be fine.)

I did warn you that the next few weeks would be mostly about Airstream maintenance, didn’t I?

The job list on the Safari is pretty long, so I’m trying to tackle at least a piece of a project every day.  The past few days Eleanor has been helping me with preliminary bits of the rest of the storage cabinets I started before our last trip.  We’ve figured out how we want to assemble the cabinet and glued up some trim pieces with aluminum strips, as Kyle and I did before.

I’ve also had the countertop made by a local wood shop. It’s black walnut, measuring about 18″ x 69″.  You might think that would be monstrously heavy, but I had it planed down to 5/8″ thick so it’s just 19 pounds.  Not lightweight, but reasonable for solid wood. We think it looks fantastic, even before final shaping and finishing, and I am really looking forward to seeing it finally installed. I’ll post pictures in a future blog.

One of Saturday’s little tasks was to tackle one of those common annoyances in the Safari-class Airstreams.  Those trailers used a type of Hehr window that opens at the bottom third of the glass.  The window operators (cranks) are made of cheap pot metal and they eventually strip and fail.  We’ve got two failed window operators in the trailer and a few others showing signs of imminent failure.  (You’ll know because you have to spin the window crank quite a while before it finally “catches” and starts to move the window.)

This is a job that the dealer will probably charge an hour’s labor to do, but you can do it yourself in less time.  The trick is finding new replacement window operators.  They’re called “torque operators” and they are Hehr part #008-192 if you’ve got the window knob on the right (as seen from inside the trailer).  I found them online for about $8, and bought three figuring that we’d need a spare soon.

Replacing the torque operators only requires two tools, a Philips screwdriver with a narrow handle and a regular (flat-bladed) screwdriver.  The job is a little tricky, and I was wishing someone would document it, so photos are below to illustrate most of the steps. In short:

1. Inside the trailer, open the window fully if it still works.  Remove the black knob by removing the screw in the center.
2. Outside the trailer, remove the two small black screws in the hinge just above the movable part of the window glass.
3. Open the window (if it didn’t operate by the knob) and pop out the C-clips on the arm hinges (one on each arm).
4. Pop the arms apart using the flat bladed screwdriver (one on each side).
5. Now you can lift the window all the way up and either pop it out of the hinge or slide it sideways until it comes out of the hinge.
6. Again using the flat screwdriver, pry the lower end of the spring off the upper arm so that the arm can move freely.  Be careful not to puncture the screen with the spring.  Do this on each side.
7. On the right side, remove the screws that hold in the mount for the round bar.  The top one will be hard to get to, so this is where the narrow handle of your screwdriver is crucial.
   On the left side, remove the three screws that hold in the torque operator.  Again, the top one is a pain to get to.
8. Drop the round bar down on the right side, then the left.  It should come out now, with the torque operator attached.  Might take some wiggling and cursing.  Don’t let the springs and arms fall off, because that will just make your life harder.

   

   

   

   

   

   

   

   

9. Remove the torque operator and note what a piece of crap it is.  Scratch your head and wonder why they didn’t make it out of more durable material.
   

   

   

10. Replace with a new torque operator, and wiggle the whole assembly of bar, springs, arms, and operator back into place.
11. As they say, “installation is the reverse of removal.”  Riiiiiight.

Getting the top screw back in on each side is a pain. I taped the screw loosely to the driver and that helped, or you could use a magnetic bit.  Getting the window back in the hinge is a hassle too.  It takes a little force.  A helper would be useful here, although I managed to do it myself in a few minutes.  The rest is pretty easy.

I’ve still got one more torque operator to replace on the other side, but with the Airstream in the carport I can’t get to it right now.  That will be an on-the-road repair sometime in May or June.  The third operator will sit in the box of spares until the Window Failure Lottery is complete and we have a known loser.  And now we can open up a window in the bedroom and let in the air again!