An existential crisis for the Mercedes GL

When I bought the Mercedes GL320 in 2009 to be our new tow vehicle, I knew I was taking a big risk.  At $66,000 (out the door, tax included), it was almost double the price of the most expensive vehicle we’d ever purchased.  Mercedes has a reputation for expensive repairs and maintenance, and their dealer service network is small compared to just about any other brand.

The justification for taking this risk is complicated, but the major factor was the diesel powertrain.  At the time, only the European brands (Audi/VW, BMW, Mercedes, Land Rover) offered diesel SUVs, and they rack up impressive performance stats.  In 2009 when we made this purchase, we were planning on many more years of Airstream travel, so it made some sense to invest for the long term. I felt confident the Mercedes 3.0 liter turbodiesel could last for hundreds of thousands of miles while carting as many as 7 people in comfort and delivering fuel economy (not towing) in the upper 30s.


In the past decade the European diesels have also been impressive for their emissions improvements and quietness. I can start my diesel dead cold in the morning at a campground and hardly anyone will even notice the sound, while the exhaust is scarcely more offensive than baby’s breath.


That’s all very nice, but there is one thing that a tow vehicle must be able to do to justify its existence: tow.  Our GL320, despite having 127,500 miles on it, has done as good a job of that as it ever has—until this week. One tiny problem this week managed to cripple it, rendering the GL entirely worthless as a tow vehicle.

We had a gentle rain on our last night at Beachside State Park on the Oregon coast.  Over a period of hours, a drop or two of water managed to work past the gasket on the right rear taillight, wick through some insulation on the inside, and drip down to a black plastic cover below.  This cover has thin vent slits in it because it houses a very expensive electronic device called a “Signal Acquisition Module” (SAM).

The water dripped through the vent slits and down to the exposed circuit board inside.  When the SAM gets wet, it behaves like any other electronic device when wet: it malfunctions spectacularly.  This SAM happens to control most of the functions in the rear of the vehicle, including trailer lights and brakes. Just one tiny drop of water in the right spot means no trailer lights or brakes.

This has been a recurring problem.  It first cropped up in February 2015 at Alumafiesta after a heavy rain, with the symptoms being taillights that didn’t work for a few hours. I didn’t find the cause until May 2015 at Alumapalooza when it happened again.  I dried the computer with a hair dryer and took it to a northestern Mercedes dealer in June.  The dealer service tech glopped everything up with black sealant and pronounced it fixed, which it wasn’t.

Water hit the SAM again in January 2016, so I dried it again and took the car to another Mercedes dealer (this time in the southwest) and they replaced the right taillight, noting this the leak was a known problem. They said the magic words that they say every time I have to buy an expensive replacement part: “This is an upgraded design, so it won’t have that problem again.”

That was a nice warm and fuzzy thought, but three weeks later the SAM decided it had suffered enough from the prior repeated water intrusions, and it died without warning—while towing in downtown Castro Valley, CA.  Imagine the fun: suddenly, no brakes and no lights on a 7,500 pound trailer in heavy traffic.

This time the hair dryer trick wasn’t going to work.  I had to tow the Airstream through city traffic for a mile with no brakes, signals, or lights to a Walgreen’s parking lot large enough to dump it.  Then I had to convince the manager of the pharmacy to let me leave the Airstream overnight.  Then I had to find a Mercedes dealer and pray that they had the part I needed—on a Friday afternoon. Fortunately Mercedes Benz of Pleasanton had the part and installed it the same day, for $1,300.

All was well until last week, when mysteriously the upgraded taillight assembly let in just a couple of drips during an Oregon sprinkle, and our expensive new SAM got wet for the first time.  You can imagine my reaction when I got into the car and the dash lit up with five warning messages—and of course, no trailer brakes.

After I ranted for a while, Eleanor and I got to work.  About 45 minutes of the hair dryer treatment got everything working except the left turn signal and taillight.  We decided to start towing toward Eugene OR (nearest dealer location).  Two hours later the left turn signal began working again.

In Eugene I had a friendly chat with the service tech, in which I explained that intermittent lack of brakes and lights means the car can’t tow. That triggers what I would call an existential crisis for the Mercedes GL320.  If it can’t tow reliably after a light rain, I can’t use it. He understood the conundrum, but had little to offer other than tearing apart the interior of the car to look for other possible leak points—at $140 per hour, my expense.

I talked with Andy Thomson of Can-Am RV about possible replacement vehicles. Andy has been a very reliable source of information over the years, despite his tendency to terrify Americans with his non-truck towing suggestions. He listed the Audi Q7, BMW X5, and the new Durango (based on the Mercedes platform) as possible replacements, but pointed out that my GL has relatively little trade-in value.

Worse, there are no suitable new diesel SUVs available.  VW screwed us all on that one. Friends at Mercedes dealerships have told me that Mercedes has quietly suspended shipments of new diesel SUVs to the US. Audi and VW of course are out of the question, and BMW’s X5 might be available but it’s too small for us.

So we’ve taken the path of least resistance. The taillight assembly has been replaced again but I’ll never trust it.  We are going to rig up a plastic shield over the SAM to block the water droplets. It’s a low tech, easy fix that will probably work just fine for the life of the car.

And, despite my momentary lapse of confidence, I think we’ll stick with the GL.  Hopefully the SAM will survive this one episode of water intrusion. To be sure I’ll test it a week or two before every trip. I still want to see the odometer turn over 200,000 miles before we re-consider getting rid of it, and more miles would be nice.

On balance the car has been everything I hoped it would be: a comfortable, confident driving, capable tow vehicle. It’s amazing to me how something so small—a drop of water— can entirely destroy the practical value of the car.

[Nerd Alert]  I’m reminded of that scene in “The Fifth Element” when the evil Zorg chokes on a cherry and Father Vito Cornelius says, “There, you see how all your so-called power counts for absolutely nothing now, how your entire empire can come crashing down because of one little cherry.” [/Nerd Alert]  We live by a tenuous thread all the time, and little moments like this make that thread briefly visible.

I guess there’s nothing for it but to keep on towin’. We’re heading to the California redwoods next.

The fall of TBM and the resurrection of the hitch

“What ever happened to TBM?”  I’ve been getting this question a lot lately.  I have hesitated to tell the truth because so many millions of men around the world look up to him —but the awful truth must come out.

TBM was vanquished by work. Yes, that killer of adventure, soiler of fantasy, shroud of exploration … sheer, overloading obligation.  I tried valiantly to break away for a few days of tent camping in the cooler mountain elevations of northern Arizona, and some day trips, but again and again I was restrained at my desk by 1,001 projects that all needed attention.

Well, don’t feel too badly for TBM.  I still ate out at a few favorite restaurants, watched a few guy movies, met some local friends, went to a car show, etc—so it wasn’t all bad.  And to rationalize the situation, I resolved that in exchange for a late summer of Airstream travel (which we have since begun) it was a reasonable tradeoff to spend a few weeks in advance chained to a desk.

I also resolved that this won’t happen again if I can help it, so I’m cutting back on various obligations and hiring some more people to help.  A new Associate Editor is taking off quite a bit of workload on the magazine, and I’m drastically reducing my involvement in events since they take a massive amount of time.  (But don’t panic—Alumapalooza will be back in 2017!)

Hensley hitch refurbishedBack in New York at Colin Hyde’s shop, our Hensley hitch was being refurbished, and boy did that turn out to be an eye-opening experience. You might recall that we disassembled it and found many more worn parts and cracks than expected.

As Colin predicted, Hensley replaced the entire lower unit under the lifetime warranty rather than trying to repair it. When Colin’s shop got the unit back, they scuffed the paint and then repainted everything (top, bottom, bars, etc) with a really good automotive enamel so it will hold up better than the paint Hensley uses.  (The orange in particular is famous for fading quickly and deteriorating.)

All the new parts were installed, and then of course we greased it, installed it, and adjusted it.  It looks better than new now, which is good because the grand total for this job was more than half the price of a new one.

The eye-opening part was discovering all the parts that had failed without our knowledge.  I knew the lower unit had cracked and suspected that the cadmium-plated steel bushings (“binoculars”) were also cracked.  I didn’t know the extent of the cracking—and it was extensive—nor that the steel cylinders where the weight bars are inserted had stretched beyond repair.

The really shocking part was the bearings. There are eight of them in a Hensley, standard automotive-type bearings and races.  You’d think that since they barely turn they wouldn’t wear.  In fact the opposite seems to be true.  Despite being packed with grease, all eight bearings and races were seriously rusted.  It seems that the lack of spinning allows water to settle without being evaporated. The “dust caps” on the top and bottom aren’t waterproof, so water gets in and stays there, particularly on the bottom bearings where the dust caps actually trap water.

Hensley hitch rusty bearings and races

The picture says it all.  Look at the rust on the bearings and the wear marks abraded into the races. These bearings were about six years old. All of them were bad.

The bearings are user-replaceable but the races are not.  Colin’s guys found a way to remove the races, which involved welding little tangs on the races so they could be punched out, but for most people the solution will be to return the unit to Hensley under warranty.  My recommendation to all owners now is to do five-year inspection and/or disassembly to check the state of these bearings, particularly in a wet climate.  When you look at this picture, keep in mind that my trailer spends 8 months of the year in sunny dry Arizona.

BMW motorcycle Quebec ferry

The end of the story is simple. I flew back to Vermont in late July, reunited with my family, cleaned up and prepped the Airstream, installed the hitch, and we got on the road.  (But in the midst of that, I did manage to sneak out two quick days of TBM activity: motorcycling north from the Lake Champlain islands, up the Richelieu River all the way to the St Lawrence through the beautiful French heart of Quebec.)

We’re now in the Airstream on a two month adventure that will take us from east coast to west, at least six national parks, and many interesting stops.  So buckle up: the blog is about to get busy again.

Refurbishing the Hensley hitch

Remember last November when we found a crack in the Hensley hitch?  We took it to a local welder in Del Rio TX and got a quick fix on it.

Well, of course that wasn’t the end of the story.  For years I’ve been saying that the hitch was due for a complete overhaul, so I took the opportunity this summer while the Airstream is parked in Vermont.  I removed the hitch and toted it across Lake Champlain to Colin Hyde Trailer Restoration.

That poor hitch was looking pretty awful.  The orange paint flaked off a long time ago, and I’ve been patching it periodically with silver spray paint. It was a patchwork of rust, flaking paint and grease. From prior experience I knew it would have a broken internal bushing (the “binocular” part) and during inspection Colin and I spotted elongated holes in various places.

Hensley broken binocular bushingsSo I called up Hensley and ordered every part that was worn or which might fail in the future, which included 8 bearings, the “binocular” bushings, some new U-brackets, dust caps, spare zerk fittings, and even a full sticker kit so we could make it look like factory-new again.  That was about $250 in parts (they threw in the stickers for free).

Hitch ball no greaseNow, Hensley doesn’t have a recommended service interval, so owners are left to their own judgement as to when an overhaul is due. I think I waited too long. It has been seven years and certainly well over 70,000 miles of towing since we got this unit (itself a replacement).

Colin called me a couple of days later to say that mine was “the worst” Hensley they’d ever seen. Apparently the battered nature of my hitch was the subject of some amusement over at the shop.

The bushings were broken not just once as expected, but into three separate pieces.  The chrome had been worn off the hitch ball.  One of the lower bearings had rusted (due to water intrusion through the dust cap).

Hensley lower cracksThat crack we thought we’d fixed?  Now it was three separate cracks running across the bottom unit, hidden by a layer of dried grease.

Worst of all, the tubes that accept the binocular bushings and weight transfer bars had stretched. Now they are oval, to the tune of about 1/10 of an inch and they have separated from the main body. The new bushings won’t even fit in.

So, after Chris spent some time at the shop degreasing and sandblasting away endless layers of paint, it was decided that the entire lower section of the hitch needed to be sent to Hensley for warranty repair.  They received it this week, and have promised I’ll get it back well before it’s time to hit the road in later July.

Hensley disassembledColin says they’ll take one look at it and decide to melt it down, but I think Hensley will repair it. It will be interesting to see what comes back.

Meanwhile Colin’s guys will continue working on the rest of the hitch. There’s really not much left of it, once we figure in all the new parts I bought, and the replacement lower unit.

We’ve decided to restore the famous Hensley orange paint (but a better, longer-lasting version, says Colin).  I have some suspicions about that too.  I figure it’s all a learning opportunity.

For now there’s nothing to do but wait. Assuming everything goes as planned, we’ll have the hitch reassembled and ready in late July, just in time for us to launch again across the country.  Our schedule calls for departure before August 1, in order to spend six weeks transiting the north country from Vermont to Seattle WA. It will be nice to take off knowing the hitch is back up to 100% again.

Major work: a new front end & other repairs

OK, brace yourself.  This post is going to get detailed, forensic, and possibly scary to the faint hearted.  We’re going to do surgery on the Airstream.

Let me start with a little about how a modern Airstream is put together.  The aluminum body rests on a steel frame (or chassis) and is fastened down around the perimeter to that chassis. This is “semi-monocoque” construction, which is normally pretty strong.  The body and the chassis work to support each other, and as long as they are well tied together everything goes well.

Now think of the Airstream’s body as a teeter-totter, with the axles being the fulcrum.  In normal towing the rear of the trailer is bouncing up and down on the road a little. With every bump, as the rear goes down, the front end is being pulled upward from the chassis. Since the chassis of the trailer is held down at the front by the tow vehicle, there’s a lot of strain on the chassis-body connection.

The longer the trailer, the more force is put on the front end. When the attachment between chassis and the front of the body loosens, that’s “front end separation.” Essentially the body is now banging on the chassis rather than being firmly tied to it. As separate units, the body and chassis are now both weaker and they start to beat each other up. The visual symptoms are things like broken rivets, stress cracks in the body, mangled aluminum and gaps around the lower edge, and other things.

Now before you panic, let me point out emphatically that all Airstreams (and for that matter, all RVs of any type) will normally flex some as they travel.  They can even flex a little when they are parked if you crank the stabilizer jacks too much.  So some movement is good–it’s a way to distribute stress across the body structure.  Airstreams are not designed to be rigid, just like a bridge or the wing of a jet.  If the wing of a jet couldn’t flex in turbulence, it would just break off.

But separate movement of the body and chassis means problems. Longer trailers are particularly likely to have this problem, and they often have a particular symptom when they are flexing too much at the front end: they develop a fatigue crack in the skin just above and forward of the entry door.  On 30-foot bunkhouses like ours, the cracks first seem to appear at the corners of the front compartment hatch–and other places, as we discovered.

The 2004-2006 bunkhouses had what I consider to be a design flaw: a large square-edged front compartment.  The hatch for this compartment created a weak spot in the body, and it also eliminated the possibility of designing a structural attachment in the front center of the body where stresses are high.  (The shape of the opening is also relevant. Airstream has since gone back to rounded corners on exterior hatches and my guess is that this is part of the reason. Square corners are weak points.)

For years Colin Hyde, of Colin Hyde Trailer Restorations, has been pointing at our trailer and two tiny cracks by our front hatch, saying “You have front end separation.”  This became a sort of game.  I would deny it, and then he’d say, “You just don’t know it yet.”  Although I could not admit this to Colin, I knew he was right and that someday we’d have to go in there and find out how bad it was.  This week became “someday.”

Airstream front hatch ext before

Here’s a photo at the beginning of the project.  The front wrap protectors have been removed along with the lower beltline trim and the hatch door.  With the door removed, it’s more clear how little structure existed to spread out stresses that are transferred from the main frame members (A-frame) through the body.  The circles show the approximate locations of cracks that appeared, and the red lines show theoretical lines of stress.

The front is a high stress area, so in older Airstreams there’s sometimes a steel plate installed that extends upward from the chassis to the front panel of the aluminum body, connected by two or three rows of rivets.  Obviously that wasn’t possible with this front hatch design.  We struggled with leaks through this compartment because the door fit differently depending on whether the trailer was hitched up or not, and also the door would jam shut when the weight bars were tightened.

Airstream stoneguard mount crackAirstream stoneguard cracks2Airstream stoneguard mount repair

These two photos show cracks we didn’t know about until the front wrap protectors were removed.  This is the mounting point for the wrap protectors. Both mounting points (on opposite sides of the trailer) had the same cracks because they were weak points. The cracks are the result of metal fatigue from repeated flexing.

These cracks were definitely letting rainwater in, which is of course the cause of floor rot, so it was yet another reminder of how serious the side effects of front end separation can be.  The cracked spots were fixed with a new aluminum plate and sealant, as shown in the third image.  But this was only treating a symptom.  The real problem was down where the body and chassis were joined.

Airstream reinforcement failure

The photo above shows a reinforcement that was installed in 2008 by a dealer’s service center. They basically slipped some cut aluminum behind the existing exterior skin around the hatch in the hope of adding strength to the corners of the door.  You can see how well that worked: completely cracked through. This patch basically replaced a weak spot with another weak spot—and again, it was only treating the symptom.  It didn’t do anything to strengthen the body-chassis connection.

To fix this right, we made the tough decision to eliminate the hatch entirely.  This would allow Colin’s guys to fabricate and install two additional ribs, and attach those ribs to the existing ribs plus the new steel frame plate and a single sheet of aluminum on the inside and outside.  In other words, we were replacing a big hole and 16 rivets with a battleship-like sandwich of aluminum, steel, and 160 new rivets.

Airstream front hatch interior before

I pitched in a little by removing the front bed and frame, lower curtain track, and all our personal stuff.  This left only the big Lifeline 8D AGM battery and the Xantrex Freedom HFS converter/charger/inverter that we installed in January, plus some wiring.

The different colored floor tiles at the front end were installed way back in March 2006 when the front compartment first began leaking. Since we now had everything out, this was a good chance to remove those tiles and finish the floor with walnut (vinyl) flooring to match the rest, so I ran out to Lowe’s and bought a box of planks and installed them.

Now, compare that photo above with the one below.  Notice the two new ribs coming all the way down to the floor where the compartment used to be, and the black steel plate with three rows of rivets firmly attaching it to the body and ribs.  That plate is welded to the steel frame below.  It takes the stress between the body and chassis and distributes it, rather than concentrating it on a few weak spots. That’s the key: you can’t eliminate the stress, so you spread it out instead.

Airstream steel frame plate interior

The photo below was taken a little earlier in the process.  It shows how the steel frame plate was welded to the frame.  Notice that in our case we chose to remove the old battery box that hung between the frame members.  We weren’t using it, and it was in the way.

Airstream steel frame plate ext

The next photo shows the exterior work nearly done.  Joe is bucking rivets with Chris (inside).  Buck riveting is a two-man job and it requires access to both sides, which is why Olympic-style rivets are often used for exterior repairs.  But buck rivets are far stronger.  Notice five rows of rivets horizontally (four on the steel frame plate and one at the aluminum panel joint above) and four vertical rows added to the ribs (plus two vertical rows that were pre-existing and two rows for the vertical aluminum panel joint).  Seriously strong.

Airstream front end new rivets

Airstream new bedroom floorThe blurry photo at right shows the interior when done.  We didn’t put the white fuzzy Ozite fabric back, as we aren’t really in love with the stuff, and opted instead for a single sheet of aluminum.  The new flooring is in place also.

By this point I had been living in Colin’s parking lot for three nights, and we still had a lot of problems left to solve.  For one thing, we no longer had access to the storage space under the head of the bed.  Also, I wanted to muffle the fan on the Xantrex, since it’s right under Eleanor’s head and it runs when the converter is bulk charging the battery.

The solution was a pair of new hatches.  We divided the compartment with a 1/2″ plywood bulkhead.  The left hatch contains the battery and Xantrex; the right side is “dead storage”.

Airstream bed hatches

The battery is now secured with two big straps.  If we have a catastrophic accident, it won’t go flying and possibly short against something (which could cause a fire).  Also, since the battery no longer shares space with any stored items, we’ve eliminated the chance that some metallic object might accidentally contact the positive lead on the battery (which would cause a huge spark at the very least).

Airstream soundproof compartment

To soundproof the compartment, I lined it with acoustical foam used in recording studios.  On the underside of the bed platform (the hatch) I layered the foam over heavy automotive sound-deadening material.  We will have to pull the mattress out entirely to access this compartment, but since there are no routine maintenance items in there, it shouldn’t need to be opened very often.

You can see in an earlier photo that the right side hatch is much smaller.  We designed this so that we could simply slide the mattress toward the bedroom door to expose this hatch.  There’s a piano hinge at the very front edge. Lying on the bed, it’s easy to put things into the compartment below.  We will continue to use this as dead storage for things we need only rarely.  Funny thing is, it’s easier to access now than it was through the old front hatch, and so I was able to pack everything we were carrying before into a space half the size!

Obviously this was a big job.  But we got a ton of benefits from it:

  • eliminated leaks at the front hatch and at cracks on the body
  • eliminated possibility of future stress-related problems stemming from front end weakness
  • quieted the inverter fan
  • front storage is more usable and accessible
  • battery is much better secured
  • eliminated potential electrical risks at battery
  • cosmetics: got rid of stained Ozite, finished flooring, eliminated cracks at exterior hatch
  • much more stable bed platform

There’s even more that we did in this service visit at Colin Hyde Trailer Restorations, but I’ll wait for the next blog to talk about that.  Just a hint: it’s a really cool improvement that I don’t think anyone else has.

Repairs in Jackson Center and beyond

In the last blog I talked about the wheel bearing replacement we did while in Jackson Center, and it occurred to me that you might wonder why I don’t just take the trailer into the Airstream Service Center for this sort of routine stuff.

The reason is simple: no time.  We arrive for Alumapalooza set-up usually on the Friday or Saturday of Memorial Day weekend. The Service Center is booked up solid for at least a week or two before the event, and a week or two after Alumapalooza is over.  Everyone always thinks that Airstream will do me special favors like building me custom trailers and opening the Service Center on a weekend, while the reality is that I have to book appointments just like everyone else.

Besides, going into the shop for work anytime before, during, or after Alumapalooza is a non-starter for us.  We’re already too busy at that time, and losing the trailer for a day while working an event would really screw us up. So although we have utilized the Service Center many times in the past, it never works out at this particular time, and that’s why Super Terry (an experienced Airstream mechanic) pitches in.

We have had an odd little problem for the past couple of years, which had gradually gotten worse.  When using the water pump, the LED lights flickered—to the point of strobing in a very disconcerting way.  We’ve also been getting massive interference on the TV when the pump runs.

I have bounced this problem off numerous people in the past, and their suggestions have always been around the idea that the pump is drawing down the voltage, and that therefore the solution is some sort of capacitor or filter to smooth out the voltage drops and spikes.  Another popular theory is that the battery is weak, but we eliminated that as a possibility when we replaced the battery in January of this year.

I’ve resisted the voltage theory even though it is appealing. No question that LED lights are very sensitive to low voltage, but at worst they should be dimming a little, not strobing on and off rapidly.  Also, we didn’t need a capacitor when we first got the LED bulbs in July 2012, so clearly something has changed.  And I needed to find out what it was before we all went nuts from living in a disco.

While in Fort Collins CO at the Denver Unit’s “May-tenance Rally” I had a chance to ask Von Campbell, an electrical engineer, and he immediately suggested that the brushes in the water pump’s motor were wearing out.  This would cause electrical arcing, he explained, and that would definitely cause noise in the 12 volt DC power lines.  This struck me as the winning answer, so I asked Super Terry to bring a new water pump to Ohio and install it for me.

Bingo!  Problem solved.  Now the lights dim slightly when the pump is running, but they do not flicker or strobe.  The interference on the TV is also now barely noticeable.

I guess when all the parts are 12 years old and have been used for … what? maybe 2,000 nights? … we’ve got to expect to replace a few things.  As with the wheel bearings, I can’t really complain.

Another issue we had was with the MaxxFan in the front bedroom.  It often whines or makes an annoying resonance at certain speeds now.  It used to be very quiet.  Since we sometimes run this fan on hot nights, it’s important that it be quiet. I noticed that the fan seemed to be slightly out of balance, and attributed the problem to that, but replacing the fan blades didn’t help (it still wobbles).  Now I’m thinking the problem is the motor itself.

Super Terry brought me a broken MaxxFan, for parts.  I stripped it down one afternoon, keeping the motor, circuit board, and a few other small parts.  Later I plan to swap out the motor and see if that resolves the issue.  It’s a lot easier to swap a motor than to replace the entire fan assembly (and hey, the motor was free).

You may recall that while traveling through Colorado we had some trouble with the refrigerator, and my theory was contamination in the propane lines.  I asked Super Terry to bring his air compressor along and we used that to blow out the lines running from the refrigerator to the propane regulator up front. No surprise–we collected about a teaspoon of dark brown oil on some paper towel in just a minute or two.

This verified my theory that we had gotten some contaminated propane.  This is a known problem, although I’m not sure how commonplace it is.  According to the Propane Education & Research Council:

Oil Residues and Heavy Hydrocarbons … This type of potential contamination can vary from very light oil to a very viscous tar-like substance. Sometimes it is a waxy material like paraffin, or it may be similar in consistency to axle grease. Sometimes it is transparent (no apparent color) while at other times it is light brown, dark brown, or even black. It usually has a strong odorant smell, as the ethyl mercaptan used as an odorant in propane appears to concentrate in the oily residues.

Source: The oils in propane can come from many sources; from processing, pipelines, pumps or compressors, piping systems, and flexible hoses.

The refrigerator had been running on gas without problems for a few days, so it was interesting to note how much oil was still left in the lines.  I suspected we hadn’t seen the last of this problem, and sure enough it cropped up again about two weeks later in Plattsburgh when we finished one tank and switched to the suspicious one.  The fridge gave me grief for a few hours but has been fine since.  I may blow out the lines one more time at the end of this summer, when that tank is nearly empty.

There was one more repair item along the way. While driving through Pennsylvania the GL’s “CHECK ENGINE” light came on.  I didn’t even have to pull out my new engine diagnostic tool (code checker) to guess that it was once again a stupid emissions problem.  The car is great but the complicated Bluetec diesel emissions system has been the cause of most of our service stops, and usually it’s not a real emissions problem but a sensor or software update needed.

We made a stop at Mercedes Benz of Lancaster (PA), where it just happens we know the general manager Chris through Airstream circles and he made sure the dealership took excellent care of us.  The problem was a NOX (nitrogen oxide) sensor, which is an expensive part but fortunately replaced fairly quickly. Chris arranged for us to be able to drop the Airstream in their parking lot and offered use of his house nearby for overnight parking. Sweet.

Airstream courtesy parking PA

Clearly it was not a bad place to spend the night.  Too bad it was too chilly to try the pool!

Our next major stop was Plattsburgh NY, at Colin Hyde Trailer Restorations for a long-anticipated major repair and upgrades to the Airstream.  That’s quite a story, so I’ll save it for the next blog entry in a day or two—along with extensive photos.