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RV Tech Q&A: March 2018

Originally Published in Trailer Life Magazine

Pressure Washing an RV

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I have a 2017 CTS192RD Coleman travel trailer with exterior aluminum paneling running horizontally. Is it possible to get water behind the panels when power washing the sides? Should I stand on a ladder so the water would be at a downward angle, or is it OK to have some of the spray going up as I stand on the ground? I don’t want to increase the chances of water getting behind the panels around the seams and creating dry rot.

Larry Young | Dayton, Nevada

Answer iconThe use of a pressure washer to clean an RV is a dicey subject, Larry, and unless you are sure of what you’re doing, it’s probably best not to use one. Yes, you can force water into places where it would not normally go under average rain conditions or when washing with a garden hose, and once that moisture is inside a wall cavity, for example, it can take a long time to evaporate.

That’s a surefire recipe for causing wood components to rot, and although it doesn’t apply in your circumstance, it can also lead to delamination. In addition, a misused pressure washer can also cause damage to vinyl graphics or paint, and it can dislodge material such as putty tape, and RTV-silicone or RTV-acrylic sealants around windows and compartment doors.

It’s more work, but the use of an appropriate cleaning solution, a brush and a low-pressure water hose is the best way to go for cleaning an RV exterior.

More Formaldehyde Smell

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Your response to J. Douglas’ “Formaldehyde Smell” letter in the September 2017 RV Clinic made sense. Some years ago, we experienced the same overpowering smell in our Aliner LXE trailer.

After an extensive search, we found the culprit: a container of holding-tank deodorant had opened in storage, and some had spilled out. Unfortunately, the various contents in that storage area were restrained from shifting during towing by foam blocks, some of which were attacked by the spilled deodorant and were melting, causing caustic fumes. A thorough cleaning with dish detergent and an all-purpose spray cleaner stopped this harmful process.

The holding-tank deodorant we were using at that time contained formaldehyde. Since then, we have used only non-formaldehyde deodorants such as Thetford Campa-Chem.
I suggest a search for any leaking liquids, especially those containing formaldehyde, and ridding your RV of all products that contain this harmful chemical.

Dave Michaels | Bedford, New Hampshire

Answer iconThank you for the follow-up comments, Dave. Sometimes it’s the easy or obvious solutions that escape us, and, in this case, spilled formaldehyde-based toilet chemicals would certainly do the job of generating excess odors. It’s always good to check for all possible causes of a problem.

GFCI Solution

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In reference to Don Hudnall’s “1995 Wiring Diagram” letter in the January 2018 issue, I have a 32-foot 1995 Holiday Rambler Aluma-Lite trailer that has also experienced ground-fault issues.

I found the problem was with the ground-fault circuit interrupter (GFCI) breaker itself. I was able to purchase a replacement GFCI breaker at Home Depot, which solved the problem.

Note: The 1995 Holiday Rambler did not use GFCI outlets, as assumed in the response to Don’s question, but used GFCI breakers instead.

Tom Moore | Tigard, Oregon

Answer iconGFCI technology made its way into RVs early on, and its application has evolved along with the hardware. Tracking down a GFCI problem, especially in an earlier-model RV, should likewise include the breaker-box components. Thank you for the suggestion.

Cold Inflation, Warm Tire

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Our 2017 Highland Ridge 293RLS fifth-wheel has 225/75R15 tires. The stated cold pressure setting (80 psi) is the same as the maximum pressure shown on the side of the tires. Because tire pressure rises in use, the max pressure will be exceeded if the tires are inflated to the stated cold pressure setting. What is the correct cold pressure setting for these tires?

Kelly Howard | Friendswood, Texas

Answer iconThis question comes up a lot, Kelly, and it’s easy to understand how people might be confused by proper tire inflation. Eighty psi is the correct cold pressure for your RV’s tires. Pressure rises somewhat when the tire warms up in operation, but the tire manufacturers build in a safety factor to accommodate that higher warm-running pressure. Maintain that 80-psi cold inflation, and you’ll be fine.

Transmission Temperature

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Regarding Bob Richardson’s concerns in November 2017’s “Manual Automatic Shift Down” letter, your reply mentioned transmission overheating. I have a 2000 Ford F-250 with the 7.3-liter diesel and automatic transmission. In 2013, it had a transmission failure, which, according to the Ford dealer, was the result of overheating. Because of this, I installed a transmission-oil temperature gauge.

I cannot find anyone, including our Ford dealer, who will provide any optimum or critical oil-temperature parameters. Perhaps with your network, you could find if there are temperatures that would be displayed on my gauge so I can monitor the transmission effectively.

While towing my 32-foot fifth-wheel at 60 mph on typical Midwestern highways, the gauge barely moves off the low-side peg of 140 degrees Fahrenheit. The temperature escalates (naturally) when positioning at a campground. It would be a great benefit to know when a potentially damaging temperature is being reached.

Jim Merritt | Branson West, Missouri

Answer iconTransmission overheating was a more frequent occurrence many years ago, Jim, but today’s vehicles are less prone to that problem. A transmission in any vehicle can overheat if abused or overloaded, if the engine has had its power excessively boosted by way of an aftermarket modification orif regular maintenance has been deferred. A transmission is a complicated piece of equipment, and it can simply fail, just as any other part can fail during regular use.

As a rule, an automatic transmission will operate at about 200 degrees Fahrenheit, or very similar to the engine temperature. Under heavy loads, for short times the temperature may spike as high as 275 degrees, measured in the transmission sump, without damaging components. The torque converter, where much of the heat-causing fluid friction takes place, can run even higher.

If your operating conditions cause the temperature to hover around that 275-degree mark for any significant amount of time, take steps to reduce that temperature. If climbing a long, steep grade, for example, slow down, shift to a lower gear and ease back on the throttle. Pause at some point to allow the transmission to cool down, and then continue keeping an eye on the gauge.

Your truck has a 20,000-pound gross combined weight rating (gcwr) and is rated to tow a maximum of 10,000 pounds. You might want to stop by a certified public scale and check the weights for your setup when ready for the road, just to make sure overloading is not a factor in your case.

Ball-Mount Rattle

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This is a follow-up to “Hitch-Receiver Slop” in the February 2017 issue. After installing the ball mount into the receiver, I push and tap a cedar shim (used by carpenters to plumb doors) into the top space and break off the excess. I carry extra shims since I always remove the ball mount when unhitched for longer periods of time. I’ve been doing this for three years, and it works well.

Jim Foster | Oklahoma City, Oklahoma

Answer iconThat’s a great idea, Jim: simple, inexpensive and effective. This might help a lot of RVers solve that annoying bang and rattle from a too-loose ball mount. Thank you for the suggestion. The Roadmaster Quiet Hitch can also take care of the problem.

Solar-Power Problem

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Regarding December 2017’s “Solar-Power Plug” letter, Sam Linkous diagnosed his own problem without recognizing it. The reverse protection diode may or may not be present unless they had existing connectors on the panels. The protection diode protects the panels but will not stop the solar panels from draining the batteries if the Coleman connections in the RV or the solar-panel connector are reversed.

I graduated in 1957 with a “radio” degree and made my living repairing the results of production over performance. The items have changed; the shortsighted attitude has not.

Geoffrey Pruett | Clackamas, Oregon

Answer iconAny manufacturer of any quality-level product can experience a mistake in product assembly, and this could have also happened with Linkous’ trailer. Your suggestion about the miswired connector is dead on target.

The easy check is to attach a multimeter to the trailer battery and observe the voltage level, then plug in the solar panels, preferably with the panels in direct sunlight, while keeping an eye on the voltage. If it jumps up somewhat, the polarity is fine for the power coming from the solar panels, although that may not detect a failed protection diode. If the battery voltage drops when the solar panels are plugged in, it’s time to check for proper wiring polarity at the plug. If in doubt, a trip to a qualified dealer with solar-charging experience is in order.

See Related Story:
RV Clinic FAQ:
Top 20 Tech Questions

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