The 7-way cable on an Airstream

Most people don’t think about the fat black cable that connects the Airstream to the tow vehicle—until something doesn’t work, like taillights or brakes.

It’s called either the “umbilical” or “7-way” cable, and keeping it in good condition is important because it’s the critical link for correct operation of trailer brakes, lights, and signals.

The 7-way, explained—

Dirty 7-Way plug
Don’t let your plug look like this

Since 1989 all Airstreams have used the same wiring arrangement. (Earlier trailers may have different wiring, but typically they have long since been rewired to fit modern tow vehicles.) Each location in the 7-way plug is dedicated to a specific signal. Two of them—the 12 volt positive and 12 volt negative—supply power to keep the battery charged while towing to prevent depleting the battery while using the electric brakes. The other pins carry signals to activate the clearance lights, turn signals, brake lights, and back-up lights (if the trailer is equipped with them).

Is your cable too long?

Take a look at the 7-way cable the next time your Airstream is hitched up. Does it drag on or very near the ground? It will wear away quickly if it touches the ground during ordinary towing. You can use a bungee cord to take up the slack. (Drooping to touch the ground only in a sharp turn is okay, since that contact with the ground will be very brief.)

The cable should have enough slack so that the tow vehicle can make very sharp right and left turns in a parking lot without pulling the cable taut. If your cable is too short, you can buy an extension cable or (better) have the entire cable replaced. On vintage Airstreams, old stiff cables are common, so replacement is a good idea anyway.

When hitching up…

…double-check that the plug is inserted fully each time. Often it feels like it is in all the way when it really isn’t. To be sure, kneel down and look at the connection from the side. There are little tabs on the plug and the lid of the receptacle on the tow vehicle, which lock the plug into place. If the plug isn’t inserted fully, you’ll be able to see it from the side much more easily than from the rear, and this will ensure it doesn’t come loose while towing and make sparks on the freeway.

Avoid corrosion

Corrosion is the major cause of problems for the 7-way plug. Just a little moisture over time will result in greenish or white corrosion on the connectors, and that will cause problems like inoperable lights or brakes.

Be sure to position the plug between trips so that the head of plug is hanging downward. That will help keep rainwater from settling in the plug. At various RV stores you can find a generic “7-way plug holder” that mounts to the A-frame, which gives you a place to lock the plug when it’s not in use.

Periodic maintenance…

…for the 7-way plug on the trailer is important. Periodically you should clean corrosion from the seven spade connectors. It’s difficult to do without the right tool, so we recommend a kit available in the Airstream Life Store which includes a burnishing tool (a special file designed for electronic use), a premium electrical contact cleaner, and instructions.

You can also use the same tools to clean the connectors in the tow vehicle’s 7-way outlet, if they need a little help. Plan to do this simple cleaning job at least once a year as preventative maintenance. With the right tools it takes just a few minutes.

With those simple checks and a bit of annual maintenance, you’ll have eliminated the most common causes of problems with trailer lights and brakes.

Sealants — A Sticky Subject

In the Airstream universe you will find a curious phenomenon: passionate debates about sealants. That’s because the constant movement of all parts on the road causes all travel trailers to leak eventually, and a good sealant 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-sealed 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-sealing. They’re busy re-financing.

The aluminum construction of an Airstream is another reason Airstreamers love to debate sealant. Common silicone sealants don’t adhere as well to aluminum, so we have to use polyurethane sealants that are more expensive but stick like crazy and stay gooey for a long time.

By the way, we use the term “sealant” because “caulk” isn’t flexible, whereas the sealants used on an Airstream are elastomeric, meaning they can stretch without breaking their seal as the travel trailer moves down the road.

Sealants, then and now

In the old days the general-purpose sealant of choice was called Vulkem, and you’ll still hear vintage Airstream owners talk about it. Like the modern sealants, it had a marvelous ability to seal gaps tightly, stick to aluminum, and remain slightly tacky beneath the surface for many years.

These days it has been supplanted by a more modern formulation that carries the same name, as well as a few other new products. Most of the recommended modern sealants have certain characteristics in common: they are sticky like hot salt-water taffy and they adhere to aluminum and plastic like glue. Once cured, they flex a lot without breaking their seal, and they are designed for exterior use (only) so they are UV-resistant and completely waterproof.

SealantAs long as you choose a sealant that meets those criteria, you can use any particular one that fits your needs. Popular choices include TremPro 635, Vulkem 116, Sikaflex 221, ParBond, AdSeal, and others. ParBond is thinner than the rest, comes in a silver color, and creates a “rubberized” seal that’s good for tight spots, so it’s typically used on small jobs. The others are great for roof work (they come in colors, so get white), and larger areas of coverage.

Where to shop

Finding appropriate sealant is sometimes difficult. 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. If you are in a rush to fix a leak, check hardware stores for a construction sealant that is guaranteed waterproof, UV stable, approved for outdoor use and which adheres to aluminum, painted surfaces, and plastic.

You can always go to the local RV store and find acceptable alternative products, but in my experience white-box RV store products seem to be made for the disposable RV market because they often break down too quickly and start to crack, then leak. By comparison, a really good polyurethane sealant can stay sticky, waterproof and pliable for decades, in places that aren’t exposed to the sun.

cracked sealant
Cracked sealant

Sticky situations

There are a few challenges with using this stuff. First off, the fumes are stinky and toxic, which means you have to beware of the fumes if you are lucky enough to have a garage to work on your Airstream.

Second, it’s trickier to shape and smooth than silicone, because it sticks to everything. The old “wet finger” trick that you use with silicone won’t work—these sealants will stick to your wet finger. Wear disposable vinyl gloves and bring along a bunch of paper towels for cleanup.

Third, keep in mind that the good sealants tend to cure very slowly. For example, Vulkem cures at the rate of just 1/16″ of an inch per day at 75 degrees F & 50% humidity. You’ll want to allow some time for a good cure before exposing the new sealant to weather.

Saving sealant

It’s hard to save the leftovers. Once you’ve opened a tube of sealant, take some care to re-seal it well for storage. There are many techniques to try to seal the tube, such as putting a golf tee in the opening, covering with the tip of a rubber glove, using food saver vacuum bags, and commercially-available storage caps of various designs. Hot glue on the tip works well.

Don’t freeze it—that method can cross-contaminate other items in the freezer (your ice cream might taste funny after a while) and the manufacturers of the sealants generally don’t recommend storing at that temperature.

Whatever you do, don’t expect opened sealant to still be usable in a year. Even if you take tremendous effort to close up the tube against outside air and moisture, it will probably cure to a solid lump in a few months. Parbond seems to be the exception. It lasts for years just by replacing the cap.

Safety first

The sealants discussed here are fairly safe but you should take a moment to read the fine print on the tubes before using them. Avoid skin contact or breathing of the vapors in a confined space. (That also goes for chemicals used to clean up afterward.) There are recommended temperatures at which you should apply sealants, and recommended techniques for application, cleanup, and storage.

Sealing the Airstream against leaks really isn’t rocket science. Generally the sealants last a long time, so the old days of climbing on the roof to “re-caulk the seams” every year are over. When replacement is eventually needed, making a good choice of product will be a key part of keeping your Airstream dry and happy.

AC Maintenance

Feeling hot in your Airstream? The quality of cooling you get from your rooftop air conditioner depends a lot on what you do. In normal operation, the air conditioner can produce air that’s about 18 to 22 degrees cooler than what goes into it. That means if the interior of the Airstream is 100 degrees, 80-degree output air is about the best you can expect initially. As the air recirculates, the temperature of the output air will drop. To get the best cooling, do what you can to park in shade, and follow these tips:

Insulate

Close curtains, shades, and blinds. Put insulation to your windows, vent fans and skylights. The “bubble wrap” type of insulation with silver coating works well and can be cut to fit.

Seek shade

If you can’t park in shade, try to park on gravel or grass. Put out your patio awning and window awnings if you have them.

Stay cool

Cook outdoors or use the microwave oven to avoid adding heat to the trailer. Limit use of incandescent lights—each one of them is like a little 10-watt heater.

Monitor voltage

“The best thing you can do for the long life of your air conditioner is to feed it the proper electrical voltage,” said Rich Luhr, author of Airstream Life’s (Nearly) Complete Guide To Airstream Maintenance. “Low voltage is bad news for the compressor.” Don’t expect your air conditioner to start with less than 103.5 volts, and running it on a day when the campground voltage is less than 108 volts is risky.

It only takes a short “brown out” to drop the voltage below a safe level and cause damage, and it can happen while you aren’t looking. This is one reason why you should have an AC voltage monitor somewhere in your Airstream, or an electrical protection device that cuts off the power when the voltage is too low.

Even newer campgrounds can have voltage problems. If it’s a hot, humid day and everyone is running their air conditioning full blast, be wary and check the voltage. Likewise, don’t run your air conditioner on a household extension cord or a household 15-amp outlet because that will add to the risk of low voltage.

Maintenance matters

Don’t use an extension cord rated for less than 30 amps (50 amps for Airstreams with two air conditioners), and never use a household (15-amp) outlet. Keep filters, condenser fins, and all other parts clean. “The last two tips are the ones people ignore the most, and that’s a shame because they are really the most important,” writes Luhr.

To maximize the efficiency of the air conditioner, clean dust off the filters regularly. Dust builds up quickly and can severely reduce the amount of cool air you get. Also, dirty filters cut down the amount of air that can circulate and will encourage frost to form on the cooling coil, which means the air conditioner is more likely to ice up.

Depending on the model of air conditioner you may have two knobs and then two screws to drop the shroud (older style), a pair of surface-mounted plastic vents with tabs to release, or a pair of small filters that can be slid out from the front.

Airstreams with ducted air (25-foot and longer trailers starting with model year 2015) have filters located above the return air grills in the ceiling. Replacement filters are available from Airstream dealers, part #382236.

To remove the return air grill on a trailer with ducted air conditioning, just pry it out with a non-marring tool at the short edges of the screen. The filter lies atop the grill.

While you’ve got the filters out, look inside for excessive dust, bugs, cobwebs, or other debris. You can vacuum this out with a brush attachment. Most filters are washable, so you only need to replace them when they can’t be cleaned or when they get torn.

View from the top

If you want to go further, take a look at the air conditioner from the roof. First, remove the shroud (just a few screws) in order to get a good look at the condenser fins and compressor coils. You can spray the fins with a water hose or compressed air, from the inside out, to clean them up, and bend the fins straight again. There’s a tool called a “fin comb” that can be used for this. Check for mold, wasp nests, and dirt, and clean everything.

If you suspect problems with the air conditioner, it’s probably best to take it to an RV technician. The tech will compare the incoming air temperature to the outgoing air temperature (the “temperature delta”) to see how well the unit is cooling. Other checks include a more thorough inspection of the components, checking the amperage draw, inspecting the condensate drain, the condition of the roof pan and mounting bolts, and perhaps oiling the fan motor.

For more about air conditioning and other invaluable maintenance tips, order your copy of Airstream Life’s (Nearly) Complete Guide To Airstream Maintenance. “Maintenance of your Airstream is not nearly as difficult as most people think, and with just a few basic tools and this guide, you can do almost every routine task yourself,” states author Luhr. “No more trips to the service center for every little thing, and you might even find that this book saves one of your vacations, if something goes wrong on the road!”

Tire Tips—Part 2

[Want to read Part 1 of this article?  Click here]

“Ignoring your tires can result in really expensive damage,” writes Rich Luhr, publisher of Airstream Life magazine and author of Airstream Life’s (Nearly) Complete Guide to Airstream Maintenance. “When a tire blows out or is run flat, it often throws off chunks of tread which whack the Airstream and damage the body. It’s not uncommon for a on-the-road tire failure to cause $1,000-2,000 in secondary damage. So let’s get to know our tires and prevent that.”

Luhr and other experienced Airstreamers offer the following tips for buying and maintaining your trailer tires—and steps to take when they fail.

How long do tires last?

“That depends on a lot of things,” said Jon Gold, presenter of a well-received safety seminar during Alumafiesta in Tucson this year. “They last until they wear out, break, get dry rot, or you don’t like the looks of them anymore. A year, or eight years. The best way to get the longest life out of your tires is put in correct air pressure,” he said.

“The second best way is to cover the wheels on the sunny side where you park your Airstream while it’s stored. Ultraviolet radiation from the hot sun causes them to dry out and get checks,” (weather-check cracking). “If you see checks on your tires, it’s time to change them even if you have tread. If a tire doesn’t look good to you—it has a bubble, or a nail—of course, get it fixed or get a new one.”

Nitrogen. What?

Some claim that filling tires with nitrogen will improve performance and gas mileage. “Some nitrogen is good, sure,” said Gold. “But air is 78 percent nitrogen. If you’re a race car driver it might make a difference, but if you’re towing an Airstream with a maximum speed of 65 miles an hour” (the optimum speed for tire care, according to Gold), “it won’t. Just put in air. If you’re obsessive compulsive and you’re someplace that offers nitrogen, go ahead.” Prepare to lighten your wallet, though; a nitrogen fill averages $6 per tire.

Buying tires

“You can buy a brand new tire that’s one month old, or a new tire that’s six years old. The price is the same. Which would you rather have?” said Gold. The answer seems obvious, and there’s a way to find out when a new tire was manufactured. Look at the four-digit code in the oval on any American-made tire—the last two numbers are the year it was manufactured; the first two numbers are the week of the year it was made. (Examples: 0111 means that tire was made during the first week of 2011. 5213? The 52nd week of 2013. You got it.)

“You can say, ‘I want a tire that’s less than six months old, and I’m going to check’,” said Gold. Make sure new tires in the shop were stored properly—on their sides, not on the treads.

Goodyear vs. Michelin

Your Airstream comes from Jackson Center with Goodyear Marathon trailer tires. “I’m not a fan,” said John Irwin, long-time Airstream owner and frequent contributor to Airstream Life magazine. “I’ve had multiple problems and blowouts over the years. I went from those to E-rated truck tires and they were worse! They failed just as often, and when they did they tore up the trailer. They shed tread but retain air, so the tire monitor doesn’t always go off when they fail and they can be back there beating the heck out of the side of the trailer.”

Irwin now uses Michelin light truck tires on 16-inch wheels. “I’m convinced those will take care of me,” he said. “They’re worth the cost—$1400, whatever—particularly for long distance travel.” Airstream began installing Michelins on the Eddie Bauer, and made the upgrade available for other models when customers clamored for better tires.

Blowout!

Airstream tire blowout“Blowouts are rare, but if you do happen to get a flat tire, blowout, or loss of air, do NOT jam on the brake,” said Gold. “Hit the gas pedal, regain control of vehicle, then take your foot off the gas and look for a safe place to stop.”

“If you brake, you put more weight on the flat and it will yank you in that direction,” he explained. “It’s counterintuitive, but instead grab the steering wheel, hit the gas pedal real quick to lighten the weight on the front, then back off. If you see or hear or feel a tire going flat, maintain control, and gradually pull over. Don’t just yank over to the side, cutting people off.”

What about a slow leak?

“If I’m on the highway and know I’m losing air, I’d rather go to a good tire shop, even if I have to go thirty miles to find one,” said Irwin. “I carry a bottle of Fix-A-Flat and put some of that in there and keep going.” Look at the labels on tire sealants. “Some have a warning that they’re dangerous for anybody who has to work on that tire later,” said Irwin. “Choose one that’s safe. It will usually cost a couple dollars more.”

Be prepared with the items you’ll need to fix a flat:

  • Breaker bar with extension and socket
  • Leveling blocks
  • Visibility: fluorescent vest, flares, flashers or cones
  • Tire pressure gauge
  • Torque wrench
  • Torque stick (only if you might let a shop put the wheels back on for you)
  • Mechanic’s gloves (optional, to keeps your hands clean)

How to change a tire

Changing Airstream tire“Everyone calls it ‘changing a tire’ but what you are really doing is changing a tire and wheel assembly. The wheel is the metal part, the tire is the rubber part, and you are going to remove them as one piece,” explained Luhr. “Later, a tire shop will remove the tire from the wheel to patch or replace it.” If you get a flat, stay calm and follow his step-by-step instructions:

1.Airstreams don’t come with the tools you need to change a tire, so it’s up to you to obtain the necessary tools and carry them in the Airstream. The lug nuts on most Airstreams require a 13/16” socket, but some may need a 3/4” socket. You’ll also need a 1/2” drive wrench (also called a “breaker bar”) and a 6” or longer extension, or a cross-type lug nut tool. To put the lug nuts back on correctly, you should have a good quality torque wrench, also in the 1/2” drive size.

2. If you are working by the side of the road, it’s a good idea to put out some flares, orange cones, or whatever you might have to warn people zooming by. At the very least turn on the hazard lights on the tow vehicle—they’ll flash the Airstream’s taillights too. Make sure you’re visible as well, by throwing on a reflective safety vest or shirt.

3. Get the spare tire and wheel out of its carrier. Check the air pressure in the spare. If it’s low, you should add air to get it up to the recommended pressure. A tire that is low on air is likely to blow out, which could make things a lot worse. If the pressure in the spare is more than 15% low and you can’t add air, you might consider three-wheel towing for a short time.

4. Next, loosen but do not remove the lug nuts of the wheel you need to remove. This is because it will be difficult to loosen those nuts once the wheel is off the ground. If you can’t get the nuts off with your arms, try positioning the wrench so you can put your foot on it.

5. Once the tire is back on the ground, you must finish tightening the lug nuts to the factory spec. The correct torque is extremely important. Under the right amount of tension, the wheel is drawn to the brake hub face and the lug bolt will be well mated with the lug nut. Too much torque and the lug bolt will be stretched, and eventually break. Too little tension and the lug nut can work off.

6. You can’t judge the correct tightness accurately by feel, so you need to carry a torque wrench, and instructions on how to use your torque wrench should come with it. For most torque wrenches you set the target torque in foot-pounds and the wrench will “click” when you’ve tightened the nut to that setting. Remember to re-set your torque wrench to zero when you are done with it.

7. Check the Owner’s Manual or documentation for the wheels to verify the correct torque, and make a note somewhere of that number so you have it handy when you have to replace a wheel.

8. Don’t let tire shop personnel put your wheels on with an air wrench. Air wrenches can put out far too much torque and overstress the lug bolts. Instead, insist they use a manual (hand) wrench, or get a “torque stick” rated for 60 ft-lbs and have them use that. Then tighten the nuts to the correct torque specification with your torque wrench. Better yet, just tell the tire shop to give you the wheels when they are done, and you can put them on yourself. That way you know it will be done right. Use the torque wrench only to tighten the lug nuts, never to remove them. It’s a calibrated instrument that can go out of whack if you use it to remove nuts.

9. It’s very important to re-check the lug nuts after the trailer has been towed for a while. This is because the lug nuts need a little time to “seat” properly. A common recommendation is to check the lug nuts with your torque wrench after 25 miles, then again at 50 miles, and one last time after 100 miles from when you changed the tire. If you don’t check and re-tighten the lug nuts to proper torque, they may loosen over time, which can lead to losing a wheel.

If you missed Tire Tips — Part One, find the complete article here.

Tire Tips—Part 1

“Your tires do a big job, and they don’t ask much of you in return,” writes Rich Luhr, publisher of Airstream Life magazine and author of the new Airstream Life’s (Nearly) Complete Guide to Airstream Maintenance. “Just keep them inflated, inspect them periodically, and replace them when they get too old or worn.”

Luhr and other Airstream experts share their top tips about trailer tires in this and the next issue of Outside Interests.

Tire pressure: the magic pill

What’s the easiest way to better your ride, decrease your tire wear, and improve braking and road handling? “Correct your tire pressure,” said Jon Gold, presenter of a safety lecture during a recent Alumaevent.

Tire inflation illustration
“You want your tire to look like the one in the middle of this diagram,” said safety presenter Jon Gold.

“When you’re under-inflated, you’re riding on your sidewalls, the thinnest part of your tires,” explained Gold. “You’re asking for a blowout.” The optimum tire pressure for your Airstream is hidden in plain sight on the side of your coach, on a metal plate.

“Typically that number is either 50 or 65 psi,” writes Luhr in his maintenance guide. “The tire pressure should reflect the loaded weight of the trailer.” If your Airstream rolls on factory-issued Goodyear Marathon ST (Special Trailer) tires, see Goodyear’s Load/Inflation tables online to determine the right psi. Incorrect pressure can cause uneven wear and other problems—some severe.

Invest in a good tire pressure gauge,

and use it before every trip (and after you set out on the road again after camping for awhile). “Buy a good brass gauge with a short piece of hose,” advises John Irwin, Airstreamer and contributor to Airstream Life magazine. “That makes it easier to get it on the valve stem without losing a lot of air in the tire.”

“Keep the gauge with your trailer tools, along with a 12-volt DC air pump with an extension cord,” suggests Luhr. “It’s a nuisance trying to find an air pump at a gas station when you need a top-up, and often difficult to get close enough to it with your trailer. Having an AC-powered air compressor at home is a convenience, too.”

Consider a tire pressure monitoring system

Keep track of your tire inflation with a TPMS. “These systems typically use sensors screwed onto the valve stems, or placed inside the wheel,” explained Luhr. “A remote monitor in the tow vehicle will alert you if the tire becomes dangerously under-inflated, or over-inflated, usually from overheating of the brake or wheel bearing parts.”

“You want to know what’s going on with your tires because often you won’t feel or see a change in tire air pressure. On multi-axle Airstreams it’s even possible to lose a wheel entirely and not feel any change in towing characteristics,” he said.

Knowing immediately what’s going on can save you a lot of trouble. Buy a quality TPMS; “this is a case where you’ll get what you paid for,” said Luhr.

Installing a TPMS means you’ll know the pressure of each tire moments after you get in your tow vehicle, every time you tow. “No more bending down and checking each tire one at a time, no more getting your hands dirty, and less time spent getting ready to tow,” Luhr said. “Don’t forget to buy a spare monitor for the spare tire, so you don’t have to slide under the Airstream to check it before every trip.”

“Tire monitoring systems will catch most threats in most cases,” said Irwin. Owner of several Airstreams and other trailer models through the years, he offers this tip: “When underway, and you’re stopped at a stop light, reach over and punch through all the tires in the system, and look for any tire that doesn’t match the others. If one is very high and hot, something’s wrong. If one is low, you could have a slow leak, or worse.” Keep in mind that pressure varies with the temperature of the environment—it climbs when tires get hot, and drops as tires cool. “The sunny side can be higher than the shady side,” Irwin said.

When and how often to check pressure and inflate?

Because of temperature changes and normal leakage (losing one to two psi a month is expected) check your tire pressure once a month. During a trip, check them weekly.

There’s no need to remove air when tire pressure increases during the day, and don’t stress out about temporary altitude changes, (such as heading up the hill for a day of skiing)—the correct pressure is the one you put in when your tires are cool before you start your day of driving. If you move to a new campsite with a significantly different altitude, adjust your tire pressure the following morning.

Do a walkaround and look for signs of trouble whenever you inflate. “Check your tires for bulges,” said Irwin. “Does it look like a bicycle tire? If it’s round, the pressure could be way too high, or it could be a slipped belt.” Check for thrown (delaminated) treads, bulges in the tread, isolated worn patches, and rapid wear in an isolated area.

Want more?  Read Part 2 by clicking here!