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RV Tech Q&A: February 2020

Originally Published in Trailer Life Magazine

Awning Cleaner

Red letter QI have a question about awning cleaners. We have had three travel trailers during the past 20 years and have enjoyed all of them. Our most recent one, a 2016 Cruiser RV Fun Finder, seems to attract mold and dirt more than our past models. I use a commercial awning cleaner on the mold, and it works well, but it doesn’t clean the stains left behind by leaves or sap.

Do you have suggestions or home remedies that can truly clean an awning?

Michael Cunningham | Syracuse, New York

Green letter ATree-related sap and stains can be a real pain, Michael. I’ve done that dance several times — and especially when it concerns the little blobs of solidified sap from fir trees, getting rid of them without damaging the awning can be a chore. Using the manufacturer’s recommended cleaner is a good start, because it never hurts to stick with approved products.

Apart from designated awning cleaners, a soft-bristle brush and detergent can help; perhaps using a degreaser-type cleaner like Simple Green may also do the trick. I’ve also — carefully — used a plastic ice-scraper-type of tool to gently pry some large pitch blobs from an awning and an EPDM rubber roof, although this process is slow and tedious at best. Under no circumstances should you use any chemical solvents such as denatured alcohol, paint thinner or other harsh chemicals on awning fabric or rubber roof material. Stick with the milder cleaners, and good luck!

Safe Weight and Tires

Red letter QI have two questions, both related to safety. I weighed my rig on CAT scales, and the printout they gave me showed front-truck-axle weight, rear-truck-axle weight, fifth-wheel-axle weight and total weight of the whole rig. Can I extract the meaningful information I need from that? The gross weight is obviously what it is, but I can’t get total fifth-wheel wheel weight or truck weight, can I?

The second question has to do with tires. My Keystone Montana fifth-wheel came with tires that are of a good load rating for the weight of the trailer, but they were manufactured in China. I am religious about always keeping the proper tire pressure in them, the fifth-wheel is never overloaded, and I never drive over 60 mph. But after reading all the gloom-and-doom articles about Chinese-made tires, that appears not to matter and sooner or later there will be a tire failure. Should I replace these tires just because of their country of manufacture?

Tom McFadden | Kelso, Washington

See Also:
RV Weight and Loading

Green letter ATo determine the separate total weights for truck and trailer, you’ll also need to weigh just the truck, loaded with the same cargo, passengers and fuel level as when you did the first weights. Be sure to get the separate rear-axle weight again. Deduct the truck solo rear-axle weight from the truck-and-trailer rear-axle weight to determine the trailer hitch weight, which is then added to the trailer-axle weight for its overall weight.

The question regarding tires is another good one that has sort of a “maybe” answer. You didn’t say the year of the trailer or how many miles, or years, are on the tires. It seems like you’re diligent about tire inflation and loading, and that’s a big step toward avoiding tire problems, regardless of the brand or country of manufacture.

See Also:
Get a Grip:
Tow-Vehicle Tires

If you’ve been running them awhile and they’ve given you no problems, that’s great. If it were me, I’d still replace them with some U.S.-made products from a name brand you recognize and trust such as the new Goodyear Endurance trailer tires.

Awning Replacement

Red letter QI need to replace the material on my RV’s electrically retractable awning. The OEM material is a vinyl of some sort, and I’d like to replace it with a Sunbrella material. I am concerned that the Sunbrella material may be somewhat heavier than the original vinyl. Do you think that this might be a strain on the 12-volt DC awning motor?

Henry Frate | Chambersburg, Pennsylvania


Regarding “Ground-Fault Goofiness” in the November 2019 RV Clinic, I have two friends who had very similar problems with GFCI outlets. In both cases the last outlet was on their slideout. The problem was finally chased down to the junction box connected to the AC power cable between the rig and the slideout. The junction box would fill with water, causing the GFCI to trip. Over time, the box would drain, and the GFCI could be reset.
The fix is to replace the junction box with a weathertight box or drill a drain hole in the bottom of the original box, so any moisture can drain out, and seal as best as possible.

Don Rondeau
El Sobrante, California

Thank you for the suggestion about a solution for a mystery GFCI problem. Those GFCI circuits can be finicky, and your useful letter will likely help some readers with similar problems.

Green letter AThe awning motor isn’t lifting the dead weight of the fabric, Henry. It’s just rolling the awning tube to retract or extend the awning with most of the weight borne by the end bearings and the awning arms. You should have no problem replacing the fabric with Sunbrella, which is nice looking and more durable.

Storage: Slides In or Out?

Red letter QWe have a 2015 Forest River 32RLTS with three slides. Is it better to have the slides in or out during storage? I would appreciate any advice that you might have.

Bill Noyer | Harker Heights, Texas

Green letter AYou should store the RV with the slides in, and that’s especially true if the unit is parked outdoors. That takes up less space and lessens the chance of leaks or rodent intrusion by way of the gaskets.

Tow/Haul-Mode Braking

Red letter QLast year I purchased a new 2018 Ford F-250 Crew Cab with the 6.2-liter gas engine and a six-speed automatic transmission with tow/haul mode. It’s a two-wheel-drive truck. We didn’t want a diesel because in the old days the diesel was very loud, and we didn’t want that and the additional cost. My last truck was a 2003 V-10 three-speed automatic transmission, and we never had any issues with it.

I have heard so much about the tow/haul-mode transmission, but it seems that on steep grades it won’t hold me back. My fifth-wheel is a 30-footer and weighs around 11,000 pounds. The first time out, we went to Pismo Beach in California and had to go down the Cuesta Grade with a 7 percent decline. The tow/haul mode worked, but in third gear the Ford was doing 65 mph at 4,300 rpm. I tried to stay off the brakes and let the truck do what I thought it should do. I don’t like going that fast, so I finally put on the brakes and shifted into second gear, which helped some. It seems to be OK on normal hills.

I talked to the service manager at the Ford dealership where I bought the truck, and he told me that the gas engine won’t hold the truck back like diesels will.

I’m wondering if I was doing something wrong. The transmission was the main reason I got the truck. The 6.2-liter with the 4.30:1 rear-axle ratio I ordered will climb a tree, but driving downhill concerns me.

Gerald King | Modesto, California

Green letter AA tow rig’s transmission tow/haul mode is not a complete replacement for its service brakes, Gerald, even with a diesel truck. In fact, a diesel has less compression braking than a gas engine, unless it’s fitted with an exhaust brake, in which case it’s very good at working with the tow/haul for safe downhill driving.

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

The tow/haul mode is designed to alter the transmission shift points for improved towing performance with a heavy load. Working with the engine-control electronics, it’s also designed to help lock a transmission into a gear, rather than hunting through gears when driving downhill using engine-compression braking to aid with safe downhill travel. Manually shifting down is a good way to start that safe downhill descent.

The Cuesta Grade’s 7 percent incline/decline is a steep one, so it’s going to require the tow/haul mode plus service brakes, judiciously used, to maintain a safe speed and arrive at the bottom with unfaded service brakes. It can also help to approach the grade at a reduced speed, as that makes it easier for your truck’s powertrain to do its downhill braking job. Better to take a few more minutes for the drive rather than suffer possibly disastrous consequences. In short, your truck is doing what it’s supposed to do.

Have a Tech Question?

Email [email protected] and include your full name and hometown. Selected letters will be answered in the monthly RV Clinic column, but time does not permit individual replies.

Man leaning over engine wearing blue shirtJeff Johnston served as technical director of Trailer Life for 20 years and has been an RV enthusiast, mechanic and writer since he could hold a wrench. In his monthly RV Clinic column, Jeff replies to Trailer Life readers’ technical questions about RVs and tow vehicles. He also serves as associate producer of Rollin’ On TV, a nationally syndicated television program for RV enthusiasts.


Jeff JohnstonRV 101RV ClinicRV DIYRV Questions and AnswersRV TechTrailer Life RV Clinic

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