Tech Q&A – May 2022
Battling Rust and Corrosion, Adjusting a Brake Controller, the truth behind tow ratings, and Water Pressure Settings
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Underside Rust and Corrosion
Q: We have a 2003 Allegro 35DA motorhome with 30,000 miles on the odometer, which we bought new. Living in the Rust Belt and using the coach a few times in the winter brings rust underneath. What is the easiest product you would use to kill the rust? I was thinking about using Klean-Strip Concrete & Metal Prep as a spray-on to remove the rust that has started. With some products, you must remove all the rust before you spray the product on. With some of the rust-type converters, you just spray it on the rusted area and then topcoat with paint. It seems like that would be a lot easier. There are so many choices out there, and there’s a lot of area to cover under a 35-foot motorhome.
Jim Passa, via email
A: Rust-proofing and undercoating a large motorhome is a big undertaking. Not many people do it for this reason, plus many RVs are stored for the winter and don’t get exposed to road salt, etc. It’s considerably easier to treat the underside right after purchase when the coach is clean and new. If you intend to treat your coach yourself, it’s much easier if you can obtain the use of a motorhome lift at a local RV dealer. If you are friends with them, you might be able to rent one on days when they are closed. Working on your back on a creeper is messy and tiresome.
Klean-Strip Concrete & Metal Prep is a mild acid. Only use a product like that for metal preparation, and then after the metal is clean and acid is off, it must be undercoated. There are many different suppliers, and it can get costly. Eastwood sells chassis and frame paints designed to encapsulate rust. Rust-Oleum also makes products designed to seal and coat rust. Good luck; it’s a lot of work. Naturally, you should follow the instructions that come with each product and always wear the proper protective equipment.
Water-Pressure Setting
Q: We have a 2012 Forest River T226SLR toy-hauler trailer. I would like to know the proper water pressure when using the city-water hookup.
Jake Becker, via email
A: If you have an adjustable water-pressure regulator, set it for 40–50 psi, which is the industry standard. Some regulators are not adjustable, but they typically limit pressure to this range also. Camping World offers regulators with a gauge for less than $25.
Black-Water Tank Leak
Q: There is a leak around the exit pipe of my RV’s black-water tank. The leak appears to be on the joint between the discharge pipe and the tank. What is the best way to repair this?
Charlie Adams, via email
A: If the tank is cracked, it might be able to be plastic welded. Check with your RV shop as some do plastic welding. Others prefer to replace cracked tanks because repairs can be messy and don’t always work. If you prefer to do it yourself, it’s less costly to buy an ABS repair kit instead of buying a plastic welder for one use.
Refrigerator Overcools
Q: We live in Idaho but travel south in the winter to enjoy warmer weather. My wife and I have a 31-foot Palomino Puma 31BHSS travel trailer that we pull everywhere we go. We enjoy the freedom and convenience of traveling with our tiny home in tow. Recently, the Dometic refrigerator started acting up and overcools everything to the point that everything inside freezes. I cleared a slight buildup of debris in the condenser drain tube, and that seemed to help. But, alas, the problem continues. What should I check next? I’m fairly handy and understand mechanical systems, so I’m seeking any advice I can get.
Steve Long, Post Falls, Idaho
A: I contacted Mr. Long and suggested that the temperature-sensing thermistor may have gotten moved out of place somehow. This story has a happy ending because he replied: “I was able to fix the problem. You are correct about the issue being a dislocated thermistor. I repositioned the thermistor and set the ‘coldness,’ and it works.”
Brake-Controller Setting
Q: We have a Coleman Lantern 17FQ trailer and purchased a Curt brake controller for my 2008 Nissan Frontier, which came with a tow package. When braking, the trailer tires lock up and skid. How do I adjust the unit?
Rick McWhorter, via email
A: Curt offers a free online tutorial on how to use its brake controllers. I recommend following these steps to properly set up your Frontier’s brake controller:
Towing Capacity
Q: We used to own an old Pathfinder travel trailer decades ago but sold it. Now we’re shopping for a new unit. I’m sure this question has never been asked before (ha!), but is there an easy way to determine how big/heavy of a travel trailer I could tow with my 2021 Ford Expedition? The way it is equipped, mine shows a maximum towing capacity of 9,000 pounds. Is it just a matter of adding the specified dry empty weight of the trailer with the weight of passengers and luggage and then estimating the weight of holding tanks, etc.? Also, I’d assume that we wouldn’t want to be close to maximum capacity to be on the safe side, correct?
The reason I ask this: One time we looked at a trailer that was actually over the limit, and the salesman told us, “You’ll be fine; the vehicle manufacturers build a bit of ‘dumb’ into the ratings because they know some folks are going to go over the limit.” Of course, I walked away from him. Thanks in advance for your help.
Kevin Klimek, Long Prairie, Minnesota
A: I’m glad you are looking into this subject before you purchase, instead of afterward as so many buyers do. I recommend using the trailer’s gross vehicle weight rating (GVWR) when matching the truck’s tow rating; that way you have a safety margin and don’t have to estimate how much cargo and fluids you’re adding with a strong chance of being wrong. I recommend being conservative, and even leaving a safety margin of about 20%. Tow vehicles are working hard when used at the maximum tow-rating limit, Also read the manufacturer’s fine print on tow ratings; they often assume only the driver is onboard, and don’t count added passengers, accessories, and full fuel loads.
High Winds
Q: We have a 2002 Scamp 16. If we are camping and high winds are forecast, is it better to have it hitched to the truck or not hitched? What is better for the truck and trailer?
Bruce Falink, via email
A: As you know, your trailer is fairly lightweight and therefore subject to high winds more than some other heavier models. If high winds are forecast, I recommend keeping your trailer hitched to the truck to sort of serve as an anchor. Also, face the truck directly into the wind if possible because doing so will minimize the effect the wind has on the trailer. If really high winds that might topple the trailer are forecast, consider parking it up close on the leeward side of a large sturdy building or natural windbreak.
Refrigerator Quits When Cold
Q: We own a 2013 Keystone Bullet Premier 19FBPR trailer. It has an Atwood gas and electric refrigerator, model HE-0801. The refrigerator works fine on both propane and electric when the temperatures are warm. But when dry camping, using the refrigerator on gas, and the temperatures drop below around 40° F, the burner will not reignite. It will keep running until it reaches the setpoint, turn off, and then, usually in the middle of the night, the alarm will sound because the burner won’t ignite.
Things I have done so far: I have checked to make sure there is adequate propane (the furnace water heater and stove work fine). I have verified the ignitor is working both audibly and visually. When I hear the ignitor, I do not hear the gas valve as I normally would when it is working at warmer temperatures. To further verify the gas supply when it is warm and working I have turned on the furnace, water heater, and burners and cycled it. This had no effect, still worked. It seems like a gas valve issue, but why would the gas valve fail only when it’s cold?
Gas valves are not too expensive, so I was going to buy one and replace it. But I found out Atwood was purchased by Dometic, and there are no parts available. If you have any suggestions, I would appreciate hearing them. Also, are other brands of parts that would work with mine?
We really enjoy spring and fall camping and usually do not have electric hookups, so I would like to get this fixed. I hate to spend the money on a new refrigerator if it is something simple and inexpensive like a gas valve.
Mike Gloudemans, Minneapolis, Minnesota
A: Electrical components are sensitive to extreme temperatures and sometimes work intermittently, which can drive troubleshooters crazy. It does sound like it may be a gas valve. I found a listing for the parts for this model online. I also found a source for service information. Hopefully, these links will help you get it going.
Sticking Slideout
Q: We have a 2008 Fleetwood Bounder motorhome. The bedroom slide (curbside) started with a problem that seemed like a gear missing a tooth: it would go out clunking/stopping, repeating until out. Coming in, it was smooth, so the idea of a broken gear made no sense. The repair shop checked out the motor and gear, finding no problem.
After talking with Fleetwood, they thought that there is an electronic controller somewhere. They found the connections in the basement where the propane tank is located. The suggestion was to switch the two connections (the other for the living-room slide) if there was a problem. This worked somewhat for a while. Pushing the “out” button results in a clicking sound until eventually, the slide went out.
On the last trip, lots of clicks, but the slide didn’t go out. I switched the connections with the same result, so switched back. Eventually, after pressing the switch many times, the slide extended. When we left days later, the slide came in easily as it always has. It works fine for coming back in. And also works fine both ways for the other slide. Could it be the switch that selects which slide? Although as I’ve said, it works fine when coming in. What to do?
Randy Dickow, Bakersfield, California
A: I suggest checking several items. Measure the voltage at the motor while the slide is operating. Also, measure the voltage at the switches when operating the slide. The switches seem suspect and may be working intermittently. They are 14 years old and may need replacement, or you may need to take them apart and inspect the innards for dirt or corrosion or arcing damage, if possible. It’s fairly common for the motors to act up because of low voltage. When checking voltage use long test leads that allow you to stay clear of the mechanism.
Dinghy Towing a Buick Encore
Q: We have a 2012 Winnebago Aspect Class C motorhome. I was told that you can flat tow the 2017 Buick Encore AWD. The only problem is they do not sell the tow bar and front-end attachment for the car. I would appreciate your advice on this matter.
Tim Babineaux, Kaplan, Louisiana
A: Unfortunately, the 2017 Buick Encore AWD is not flat towable, as the drivetrain will be damaged. It can only be towed on a trailer (not on a tow dolly either). The only flat towable 2017 Buick models are the Enclave and Envision. Please refer to the 2017 Guide to Dinghy Towing.
RV and auto manufacturers don’t sell tow bars or related attaching hardware. For those, you go to tow-bar manufacturers such as Blue Ox, Curt Manufacturing, Demco, Roadmaster, etc.
Rough Riding Ford F-53
Q: We have a 2018 Winnebago Intent Model 31R on the Ford F-53 chassis with the Triton V-10 engine. A recent truck scale weight is 15,820 pounds, which is 180 pounds under the GVWR of 16,000. As we travel the byways, highways, and interstates, we find some roads that provide a rough ride. I run the recommended tire pressure of 82 psi all around. A tire tech suggested 90 psi, but that results in an even rougher ride. The tires are Goodyear 245/70R19.5 G7-0/RV. Are there any suspension modifications, techniques, or tricks to smooth out the ride?
Chase Reid, via email
A: The information I have shows a GVWR of 18,000 pounds, not 16,000, although Ford supplied both ratings. I assume that you weighed it on a truck scale. Hopefully, you recorded the individual corner wheel weights. Use a load-inflation table to determine what tire pressures to use. If tires are overinflated they will give a harsher ride, so set pressures according to load at that axle divided by the number of tires. Just don’t underinflate to get a softer ride.
The F-53 chassis has a reputation for a harsh ride and swaying, and a number of modifications have been developed. Premium aftermarket shock absorbers such as Bilstein or Koni can help. Try these mods first and let us know if you want to go further and have the budget for it. Other modifications include air bag springs, SumoSprings, Davis TruTrac, and anti-sway bars.
Tire-Pressure Comment
Q: We have a 28-foot Jayco Jay Flight travel trailer. I just wanted to add to an answer you gave in January’s Tech Q&A under “Tire-Pressure Tips.” The person updated the tires on their travel trailer to radial versus biased-ply tires. The new tires specify the maximum pressure limit of the tire is 60 psi. They stated the trailer sticker indicates a maximum of 50 psi. They asked which should they follow, and you said until the unit is weighed follow the maximum pressure listed on the sidewall of the new tire.
This is inaccurate; the wheels that came on the trailer from the manufacturer are only rated for a maximum of 50 psi regardless of which tire is mounted on them! This is a common mistake and the wheels/rims are even stamped inside with the maximum psi rating.
Jim Elmore, Taft, California
A: Thanks for writing, Jim. If the maximum rating of the wheel is lower than the maximum rating of the tire, the lower of the two should be used for inflation. Owners should also make sure that the new tire will have sufficient load-carrying capacity at the pressure being used, for the actual weight being carried.
