Dewinterizing A Motorhome

By Mark Quasius, F333630
March 2017

For motorhome owners whose winterized coaches have spent months in storage, the arrival of spring is an exciting time. But as much as everyone would like to hit the road, prudence requires a bit of preparation before you begin another season of RV travel.

One key area to inspect when awakening a motorhome from its long winter’s nap is the electrical system, including the batteries. Most motorhomes have two battery systems — the batteries that start the vehicle and the deep-cycle house batteries. Be sure to take appropriate personal safety precautions when working with batteries, such as wearing gloves and eye protection.

If 120-volt electrical power was available while the coach was in storage, ideally the batteries were maintained via an on-board battery charging system. If power was not available and the electrical systems were disconnected and shut down, first check whether the batteries still hold a charge. Flip the battery disconnect switches or reconnect battery cables that may have been removed when the motorhome was in storage. If the batteries are up to voltage, you are ahead of the game. If the batteries are dead, recharge them. Then test that they can hold a charge so as to power the motorhome accessories or start the vehicle.

With the battery cables detached, inspect the connections. They must be clean and free of corrosion. To remove corrosion, start by using a small wire brush, and then spray the connections with a battery terminal cleaner or apply a homemade solution of baking soda and water, which neutralizes the acid. Rinse off the solution with water, and brush off any accumulation in the hidden areas where the cable end meets the battery post or lug. When finished, apply battery terminal sealer spray to the connections to prevent future corrosion.

If the motorhome has flooded (wet cell) batteries, check their water levels. Excess charging voltage can cause boiling of the electrolyte, resulting in loss of battery water. Top off the batteries with distilled water; tap water can cause mineral buildup inside the battery. Note that AGM batteries are not flooded, so this task is not necessary. Charge the batteries to their full capacity and test them. A refractometer is handy for measuring the strength of a battery’s electrolyte solution (and also can be used to test antifreeze). If the house batteries are not holding their charge as well as they once did, it may be time to perform a load test.

Also inspect the electrical wiring. Rodents have been known to eat through wiring insulation, so be sure to check wiring harnesses carefully for evidence of such activity. This includes wiring in the engine compartment as well as under-dash wiring and wiring in the coach basement.

Connections can corrode while in storage. One susceptible area on the rear of a motorhome is the trailer lighting socket. This typically is used to connect to a towed vehicle. Open the cover and inspect the connector pins. If the pins are tarnished or have a crusty buildup, clean them. A spray can of battery terminal cleaner might do the trick, or a small brush or piece of emery cloth might be needed. In extreme cases, the socket may have to be replaced.

Readying the fresh-water system is one of the most time-consuming tasks. The system may have been winterized by blowing out the lines with air, or RV antifreeze may have been pumped through the lines. With any luck, no damage will have resulted from freezing temperatures. However, there are no guarantees, especially when air has been used instead of antifreeze. Residual water that settled into an area may have frozen and cracked a line or fitting. Therefore, while refilling the system with fresh water, check for leaks.

Leaks will be most obvious from fittings that have cracked because of freeze damage. You may also want to perform a test to detect smaller leaks. Put some water in the tank, turn on the water pump, purge air from the system, and then close all the faucets. If the pump cycles, you may have a leak.

Once you know the system is leak-free, flush it thoroughly. RV antifreeze is safe and nontoxic, but it leaves a bitter taste. I prefer to fill the fresh-water tank and lines with water and allow the water to rest for a day or two, because in my experience, this helps to remove the bitterness. Then drain the tank and refill and flush the system. The flush process may have to be repeated several times to completely remove the bitter taste.

During the storage period, bacteria may have grown in the fresh-water tank and potable water system. When sanitizing the system, I add 1/2 cup of plain, unscented household bleach (5 percent sodium hypochlorite solution) to one gallon of water for every 15 gallons of fresh-water tank capacity. Some RV experts suggest a less concentrated bleach solution — 1/4 cup of bleach to one gallon of water for every 15 gallons of tank capacity.

Pour or pump the bleach solution into the water tank, ideally through the water hose, and fill the fresh-water tank with water. Open the faucets (both hot and cold) one at a time, and use the water pump to run water until you smell chlorine at every fixture. Allow the solution to sit in the tank and pipes for at least four hours, and then empty the tank and flush the system with clear water. It may be necessary to flush the system for quite a while until all of the chlorine taste is gone. Once the system is flushed, be sure to replace the water filter elements. This is also a good time to check that the screen filter at the input side of the water pump is in good condition and not filled with trapped material.

Once the fresh-water system has been serviced, drain the black-water and gray-water holding tanks, and then add a bit of water to each tank. After the dump valves have been closed for a day or two, carefully remove the drain cap from the sewer hose connection. That area should be clean and dry. If liquid comes out when the drain cap is removed, the dump valves have a slight leak.

Most RV dealers stock replacement seals for the valves. However, if a valve blade is pitted, the entire valve may have to be replaced. Fortunately, replacement valves are inexpensive. Each valve is secured with just four machine screws. Depending on how accessible the valves are, it can either be an easy do-it-yourself job or you might need an RV service center to do it. If you do it yourself, dump the tanks, let them drain thoroughly, and then replace the drain valves. You will be all set for the next season or two.

A tank-type water heater may contain an anode rod. An anode rod is a sacrificial device designed to erode in order to prevent rust from forming in the tank. Atwood models have an aluminum tank and don’t need an anode rod. In fact, Atwood cautions against their use. However, steel tank water heaters made by Suburban do have an anode rod. The anode is part of the drain plug, so remove the plug and inspect the rod for erosion. If the rod is badly eroded, replace it. Some owners of Atwood water heaters choose to replace the nylon drain plug in their heater annually. When installing either an anode rod plug or a nylon drain plug, using a little Teflon tape on the threads can help to ensure a good seal.

At this time, take a peek into the tank. If sediment or lime has built up in the tank’s base, flush it out to allow the water heater to operate efficiently. Inexpensive flushing tools are available at RV dealerships, camping supply stores, or online. This step does not apply if the motorhome is equipped with a tankless on-demand water heater.

Mice and other pests like a warm home with plenty of things to chew on, so inspect the motorhome interior for signs of rodent damage. Clean up droppings, disinfect those areas, and repair the damage. Clean or replace the HVAC filters that typically are found on return-air ducts or registers. Run the furnace and air-conditioning system to verify that everything is operating correctly and to purge odors from the system.

Check the appliances. Be sure the water heater bypass valves are open and that the water heater tank is filled with water before operating the heater. If the heater is operated dry, the tank will be damaged. Turn on the water heater to verify that it produces hot water.

Refrigerators can become moldy inside if they don’t have enough ventilation when in storage. Before switching on the power, wipe the refrigerator’s interior thoroughly with a disinfecting cleaner. Then check that it cools as it should on each power source — as equipped — and that the ice maker works properly. If you winterized using RV antifreeze, the first few cubes most likely will be pinkish, so run a few batches through the ice maker and dump them out.

Verify that your propane cooktop or oven is operating correctly, if you have one. If the coach is equipped with a dishwasher, run an empty load with soap and hot water to clean it out and remove RV antifreeze.

Don’t forget to change the batteries in the smoke detectors and carbon monoxide alarms. Inspect the fire extinguishers to make sure they are ready.

Ideally, the engine and chassis were serviced before the motorhome was placed in storage. If not, do it before the travel season begins. Obtain filters and lubricants for the engine, transmission, and other components. Grease the suspension and driveshaft universal joints according to the service schedule, and inspect everything carefully. In addition, feed grease into the grease fittings that lubricate the air brakes, and check and lubricate the calipers of hydraulic brakes. The generator also should be serviced. If you’re not comfortable doing this work yourself, take the motorhome to a reputable service facility. Refer to your motorhome’s manuals for the exact procedures and service intervals for the chassis and generator.

Leveling jacks also need occasional attention. Some motorhome owners extend the jacks to remove pressure from the tires during long-term storage. Wipe the jack cylinders with WD-40 and then remove it using a dry rag or paper towel. This will prevent dirt on the cylinder from getting pressed into the seal when retracted.

Tires are a critical part of motorhome safety. Check the air pressures and inflate to the prescribed pressure before driving the coach. Inspect the tires for wear and sidewall cracking. Most motorhome owners don’t put enough miles on RV tires to wear out the tire tread. But the sidewalls do dry out, and cracks can form when tires sit in one position too long. Tires contain natural lubricants, but they are released only as the tires flex when being driven. If the sidewalls start to crack or show signs of dry rot, replace the tires to prevent a blowout when traveling.

Basement compartment door hinges and latches tend to stiffen up from lack of use. Oil the hinges and work them a few times to allow the lubricant to penetrate. Lubricate the latch mechanisms. Squirt graphite-based lock lubricant into lock cylinders. Then, work them back and forth with their key a few times to keep them operating smoothly. Massage a bit of silicone spray into the rubber seals around the basement compartment doors to prevent them from drying out and cracking.

Next, thoroughly clean the motorhome exterior so that dirt doesn’t accumulate, etch into the paint finish, and become harder to remove later on. Once the exterior is clean and shiny, apply a wax or poly sealant to protect the finish.

 Examine the windshield wipers. Run the windshield washer and observe the wipers. If they leave streaks or large gaps that don’t wipe clean, or if they chatter, the wiper blades should be replaced. If they aren’t too far gone, try wiping them with an alcohol-soaked towel to remove the chalking on the blade’s edge.

Finally, check for cracked sealants and reseal as necessary. Sealants wear out over time and crack or peel, which can allow water to enter the coach. Windows, door frames, vents, and rooftop plumbing protrusions all need a bead of sealant to prevent water intrusion.

After the motorhome is properly prepared for spring, all that’s left to do is fill the tank with fuel, load up the family and cargo, and hit the road.