By Ken Freund
July 22, 2016
Filed under RV Tech Q&A



We’ve been looking to purchase a motorhome, but are not sure which class yet. I have been unable to find any government crash testing of motorhomes and between manufacturers. My assumption would be that Class B and Class C motorhomes would be safer because of the crumple zones and air bags in the cab structure.

Michael Hersey | Via email


CP-InfoMotorhomes are exempt from testing. Heavy and large vehicles are at a great advantage in collisions with smaller vehicles thanks to the laws of physics. However, not all Class A motorhomes would fare the same in various types of crashes, nor would all Class B or C motorhomes. Large diesel motorhomes built on a truck chassis with a conventional truck-style cab that have the engine in front are likely to provide the most occupant protection, followed by large diesel pushers. Air bags can certainly help in frontal crashes, but so can tons of steel, which can prevent intrusion from other vehicles or objects into the cab area. Of course, seat and shoulder belts up the safety factor as well. The extra mass a Class C has behind the cab might help in a glancing impact with another vehicle compared to a lighter Class B with the same cab. However, the extra mass of the C would not be an advantage if both the Class B and C with the same cabs impacted an identical immovable object such as a big tree at the same speed and angle.

Rollover crashes really depend on the strength of the structure. Rear-enders usually don’t seriously injure belted-in motorhome occupants. So as you can see, it really depends on what kind of crash you are in, as well as the type and construction of the motorhome.


Starting Engines in Storage

I have a question that has bothered me for years. We have a 2006 Winnebago Navion on a Sprinter chassis with a Mercedes-Benz five-cylinder diesel engine. It’s kept inside, and we don’t drive it in winter from November through April. Should the engine be started at all during that time, or not at all?

Jerry Moore | Hudson, Michigan


This is a question that is certain to stir up debate. Some owners start their engines occasionally, typically monthly, and say they have good results. Others don’t start them, and say they have good results.

I prefer to put fuel stabilizer in the tank and run it so it gets into the filters and injectors. Then prior to shutdown I like to spray some marine fogging oil into the air intake (after the air filter) to protect the cylinder walls from rust. I then leave it as is for the winter without starting it. I also recommend that the oil and filter be changed before going into storage, so that there’s less chance for sludge to form and for acids in the old oil eating away at the engine’s innards. Old oil may also contain moisture, which can form rust inside the engine. When you start an engine, the cold combustion forms moisture, which fouls the oil and condenses in the exhaust system to form a mild acid, which eats away the metal. If you choose to start the engine, you should drive it and get it fully warmed up, rather than just letting it idle for a few minutes.


Humming Jayco

We have a 2015 Jayco Precept 31UL. Jayco placed the AC power converter under the bed on this unit. The unit hums continuously, all night long. Jayco’s fix was to have holes or vents placed under the bed to reduce the time the fan motor runs. But the problem is that the unit hums even when the fan is not running. On the Jayco Owner’s Forum I have found other people who have this problem. A couple of the correspondents stated that the problem is a “faulty transfer switch solenoid relay.” Others, including myself, were told by RV service centers that the hum is normal. Can you provide any insight into this situation? If I had been allowed to spend one night in this motorhome before purchase, I would not have bought it.

Joseph Fischer | Via email


I’m a light sleeper, and a noise like this would bug me too. Some sleep like a log, and this is probably what Jayco was hoping for when choosing this location. I don’t think you have a faulty transfer switch solenoid relay. Many power converters contain a transformer that operates on 120-volt AC power at 60 Hz, and by their nature they buzz at this frequency. This is also related to price: A lower-quality converter will probably make more noise than a higher-quality unit. You can’t change that — unless you make a scientific breakthrough. So what can you do? Surrounding it with sound-deadening material would insulate it, but you don’t want to do that because it will overheat. So, the best thing to do is move it. Have an electrician remount it in a place where it’s fairly close to the power panel, but far enough from sleeping areas to avoid this noise problem in the future. Depending on the type of converter you have, you could also consider replacing it with a better-quality converter with the so-called “smart charging” feature that we frequently refer to on these pages. Your battery(ies) will thank you!


Freshening the Water System

Last year I bought a Winnebago Minnie Winnie Class C motorhome. My only problem is that I can’t get the smell out of the plumbing system. I thoroughly sanitized it, had it winterized, sanitized it again, used a deodorant for the freshwater tank, etc., and it still has an odor. It was most prominent from the water heater. But if I haven’t used a faucet for a while, such as in the kitchen, even the cold water has that awful smell. Any suggestions?

Darlene Nelson | Spokane, Washington


From your description, it seems like the hot water may be the culprit. First, consider your water source, particularly if it is well water. Water with high sulfur content can cause this problem. A change of the water source will often cure the problem. Otherwise, drain the tank into a large bucket. Check the anode rod in the hot-water tank (if equipped) because it’s probably just about gone. Replace if necessary. Add chlorine bleach to the freshwater tank, using about 1 cup per 40-gallon capacity. Using the onboard water pump, run this mixture through the water system, including the faucets and water heater. Let it sit overnight to sanitize the tank. Drain the tank and refill with fresh water. Add a cup of baking soda by mixing it in a bucket and pouring it into the tank. Run this mixture through the system as before, making sure you open each faucet to flush the bleach water from the system. This should freshen things up, and you can then drain the baking soda water and refill with fresh water. You can also leave the baking soda water in place because it’s harmless and will be diluted as you add more water to the tank.


Leveling Jack Care

I have a 2012 Thor Challenger 37KT Class A motorhome. What is recommended for cleaning and lubricating the motorhome’s leveling jacks?

O.D. Dearman | Eatonton, Georgia


You didn’t mention what brand you have, but HWH has a free Adobe PDF file online ( that discusses the company’s recommendations. In part it reads: “If the jack is extended, use soap and water or WD-40 on the jack rod then wipe the rod dry with a clean cloth. Do not use a dirty rag to wipe the jack rod or do not wipe the jack rod if it is coated with dirt. This could scratch and damage the rod. Make sure to use water or WD-40 to loosen any dirt before wiping the jack rod.”


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