Maintain Your RV Generator: 10 Ways to Keep You on the Road

We absolutely love the freedom living in an RV provides us. Unfortunately, we are still dependent on the amenities that living in this age afford us; namely, we count on our electricity. I use my water heater, my curling iron (or straightening iron, depending on my mood), my computer and phone chargers, plus my nightly “white noise” fan every day/night. When we’re parked at a full-service RV park, the use of electricity poses no problem. When we boondock, however, we count on our generator to keep us “plugged in”.

After having unlimited access, it’s easy to forget that, without regular attention, our generator will leave us powerless at the most inconvenient times. Sadly, this has been historically proven. For example, during the first summer, we stayed in one location. While our rig was plugged into the shore power, the generator remained idle. We seriously didn’t even think about it. When we needed it, however it hesitated and then stalled after an hour. Plus, the service indicator light started blinking. What happened?

Over time, we became more familiar with our generator and learned what need to be done to avoid (or, at least reduce) issues.

Note: Although the Onan generator is the most prevalent brand found in most motorhomes, you should follow the guidelines for your generator type.

There are gasoline, diesel, and LP-gas generators and not all behave similarly.

1. Practice Preventative Maintenance. The first thing to be aware of is that you need to perform regular maintenance on your generator before any problems exist. These checks are essential for identifying and preventing potential problems that may lead to a mechanical breakdown, malfunction, or failure of a system or component of your generator. This maintenance consists of adjusting, cleaning, inspecting, lubricating, and servicing your generator.

Before you start it, you should at least check the generator set for oil or fuel leaks; check the oil level and inspect the exhaust system to ensure there are no leaks and that it’s correctly mounted. Additionally, make sure all CO2 detectors in the RV are properly working.

To keep your generator working reliably for years to come, follow the suggested servicing intervals, as well as the operating and storing procedures. Ours is complicated because it doesn’t slide out, which means servicing is more time consuming, as well as more expensive. Therefore, preventative maintenance is especially important.

2. Exercise Your Generator. The most common problem with a generator is failure to start due to inactivity. Generally, you should exercise your generator with at least a 50-percent load, for at least two hours every month. In fact, there are so many problems that inactivity can cause that it doesn’t even make sense to refrain from starting it periodically, even if you are stationary. Additionally, troubleshooting the RV’s generator at a repair shop can be confusing and costly, especially when—like ours—it doesn’t slide out.

A motor left with old gas or diesel sitting in the carburetor is likely to form a sort of lacquer that is prone to plugging up the generator’s idle jets. In fact, fuel-related issues often occur within even a month of sitting idly. Worse yet, this sticky material will sometimes stop a generator cold. The process of starting your generator also re-lubricates your engine seals and assists in the prevention of carbon buildup. Exercising your generator makes it more reliable, more fuel efficient, and extends its life, as well.

Make sure to check your generator owner’s manual for the load ratings specific to it. Also, remember when exercising it, that it is always better to let it run for longer periods than it is for briefer ones. This circulates new fuel through the lines and lubricates the internal parts of the motor, giving the electrical bearings a fresh spin. Additionally, spinning the bearings ensures they do not collect rust.

Although we had problems with it early on, we have avoided them by simply running our RV generator — or exercising it — on a regular basis. This helps avoid issues related to it sitting idle for long periods of time.

3. Schedule Routine Maintenance. For generator sets, scheduled maintenance is performed in set intervals based primarily on hours of operation. Scheduled maintenance is designed to keep a generator in top operating condition and prevent its untimely breakdown, as well as reduce repairs (and repair costs). Make sure to read your warranty information, as well as the owner’s manual to determine who is responsible to pay when it comes to routine and scheduled maintenance. This is especially important because scheduled maintenance that is required and not performed can often make your warranty void, as well as shorten the life of your generator.

Make sure you monitor the generator’s hour meter and perform the servicing or take the RV to a repair shop at specified intervals. The owner’s manuals of most generators have specific, periodic maintenance schedules listed and provide a space to keep track of the maintenance records of all other maintenance performed.

4. Clean Your Generator’s Air Cleaner. The generator’s air filter is designed to keep dusty air from entering the air intake of the motor. Driving down desert roads, however, can coat the air cleaner with a fine powder. Additionally, by regularly cleaning or replacing the filter, you provide a richer fuel mixture that aids efficiency and lessens premature wear on the components of the internal engine, as the extra fuel washes away the oil.

Step 1. As a general rule, the air filters of most Onan diesel generators need unrestricted access to fresh air. Therefore, the filter is usually quite easy to get to, making it relatively easy to change. Normally, the air filter assembly is found at the bottom front of the Onan generator. Just unscrew the wing nut that holds the cover onto the filter housing to reveal the filter.

Step 2. Once the wing nut is off, remove the cover to reveal the air filter. Pull out the filter and examine it; if it appears dirty, replace it. There are several aftermarket brands available at auto parts stores.

Larger Wal-Mart stores stock them, as well. Once the new filter is seated in its socket, replace the cover over the filter, threading the bolt through the center and screwing the wing nut back onto the bolt until it is snug in place. Make sure not to over tighten.

It’s imperative that you check and clean your generator’s air filter frequently. Otherwise, the buildup of dirt may enter the entire generator’s system and reduce its ability to cool itself. Although some can be cleaned out by blowing compressed air through them, some need to be washed with soapy water, and others have to be regularly replaced.

5. Change the Generator’s Oil. Depending on the model, generators are designed to run for 75 to 200 hours between oil changes; and just like your lawn mower, if you forget about it, you’re most likely going to have problems at the end of the season, or worse. Maintaining the regular service of your generator keeps it reliable and ready to go.

Step 1. Changing the oil is quite simple on most Onan generators. Merely start your generator and let it run for about five minutes to make sure the oil is warmed up enough to easily flow out. If you run it longer than that, it will be too hot to change and you may get burned. You just want the oil viscous enough to completely drain from the engine. If your generator has already been running for a while, let it sit for an hour or two before changing the oil.

Step 2. Once the generator has been warmed, remove the cover to the oil fill access point on top of the generator, so there isn’t a vacuum while draining the oil from the drain point. If you don’t open the oil fill access point before opening the drain bolt, draining will take far longer.

Step 3. You will have to crawl under the RV and drain the oil. The oil plug is easily visible and can be removed with a wrench or socket set with little trouble. We recommend using an empty, gallon water jug — preferably the more modern, sturdy, round kind that has a handle built into the side like the Ozarka brand gallon water jug containers rather than the plastic milk carton type — and a small funnel. This not only gives little distance for the oil to spill — reducing splashing — but also holds all of the oil perfectly, allowing you to cap it and take it to your nearest oil reclamation facility easily.

Once the oil has completely drained — usually about five minutes or less — replace the oil drain bolt, making sure it is snug and not cross threaded. Remember to avoid over-tightening.

Step 4. The generator has an access door on the bottom side. You may have to loosen the exhaust pipe bolts in order to open it and then set the bolts aside in a safe location so they don’t get misplaced.

Open the door on the bottom of the generator by pinching the access point with your thumb and index finger. You will find the fuel filter on the left-hand side and directly behind it on the right is the oil filter. Use a standard oil filter wrench for removal, since ratchet oil removal tools are too large to fit in the space and you may risk tearing the oil filter in the process.

Step 5. Once you’ve loosened the oil filter, remove it the rest of the way by hand. Oil will pour out of the old filter, so be sure to have some cardboard on the ground below to catch the dross.

Throw away the used filter and prepare the new one for installation by applying some fresh oil on the rubber gasket of the new filter with your finger. This will help seal it properly when installed. Screw it on by hand or use the filter wrench to tighten it down. Avoid over-tightening. Move any loose wires out of the way and close the hatch. Make sure your exhaust pipe is in place if you needed to remove the bolts.

Step 6. Crawl out from under the RV and with a funnel, slowly add three-quarts of oil (refer to your owner’s manual) into the top of you generator. Close the oil access point back up.

Start the generator, which may take a few tries. You will hear clicks as the engine primes. Run it for a few minutes to cycle the oil and be sure to replace it again after no more than 250 hours of use, checking your oil level periodically throughout that period.

Note: Types of oil to use vary depending on the season you are currently in, so refer to the Onan manual for which one to use. The manual can be found online as a PDF file on the Onan web site.

6. Change the Fuel Filter. There are two sure signs that you should change your fuel filter. The generator may begin surging or shutting off when you put a new load (that normally wouldn’t be a problem) on it. When it shuts off, the engine will give a “code three” service fault indicator, by blinking three times. Basically, stick with the 500 hours changing interval religiously to avoid this problem since it’s an easy fix that takes five minutes and saves a ton of frustration.

Step 1. The fuel filter on almost all Onan generators is found in the access bay on the underside of the generator, in the same location as the oil filter and spark arrestor. The fuel filter is the easiest to access and requires two wrenches to remove. Use one wrench to loosen the two hoses that are connected; there is one on each side.

A small amount of fuel will begin to spill out as you loosen the lines, as one is a sending line to the generator for the fuel and the other comes directly from your main fuel tank for the engine. Keeping your arms as high as you can, as you unscrew them will prevent diesel fuel pouring down your arm, which can be rather unpleasant.

Step 2. Once the lines are released from the filter, use your second wrench to release the bolt in the center of the filter that holds it in place. Once it is completely loosened, remove the old filter and reattach the new one to the generator with that same bolt by placing it through the filter and reattaching the nut on top of the filter. Snugly reattach the fuel lines with your larger wrench.

Step 3. Close the access panel, and crawl out from under the RV. Go to the generator and hold down the start button for twenty seconds or so. You will hear a clicking noise, as the generator primes the engine, filling the new filter. If it doesn’t start right away, prime it a couple times more to fill the filter with fuel until the engine turns over and starts pumping normally.

Onan suggests that the replacement intervals on the fuel filter are 500 hours. If you run low on fuel and continue to use the generator, your filter may become clogged more rapidly and need more frequent changing, as sediment at the bottom of the fuel tank will be pulled in more readily.

Note: Buying two fuel and oil filters is a good practice, as you will always have a replacement on hand when an auto parts store isn’t available. Also, keep a log of the run-time hours you changed your filters at. There are generally two of these “clocks” in every RV for the time used on the generator.

7. Pay Attention to Weather Conditions and Altitude. There are a few other things that may make your generator operate incorrectly. Pay attention to the generator’s operating conditions, such as the altitude and current weather conditions.

For carbureted gasoline generators, it is important to properly adjust the altitude setting when traveling through the mountains and then readjust the settings when you return to lower altitudes. Additionally, it is likely necessary to change the air filter, oil, and oil filter more frequently in dusty conditions. This maintenance helps extend the life of your generator.

8. Properly Store Your Generator. When you store your RV, it is essential that you properly prepare the generator for inactivity. We have a diesel generator and we live in our RV full time, but for those who put theirs in storage during the off-season, this is a necessary step.

With a gasoline generator, you want to fill the motorhome’s fuel tank and add a fuel stabilizer like “Sta-Bil.” Just follow the instructions on the fuel stabilizer, and then, run the generator, as well as the engine with a half-rated load to get the fuel stabilizer throughout the entire system. Most are capable of protecting the fuel system and components for at least six months or longer.

Since acids that corrode the engine bearings can accumulate in used oil that is allowed to sit for long periods of time, it is important to change the generator’s oil and its filter before storing it. It is advised that you start your motorhome and the generator periodically while it is in storage. Check the water level in the battery cells and keep them clean and fully charged. However, if you aren’t planning to start your RV or its generator while it’s stored, you should make sure the batteries are fully charged and the battery cables are unconnected.

9. Beware of Carbon Monoxide Poisoning.

Carbon monoxide is a sneaky and silent killer and when you are operating any generator, there is a threat of carbon monoxide poisoning, so make sure to follow all of the cautions and warnings found on your carbon monoxide detector and in your generator owner’s manual. Also, make sure that everyone in the home knows what the symptoms of CO2 poisoning look like and what to do if they are exposed to this poisonous gas. The symptoms include:

  • Confusion
  • Dizziness
  • Headache
  • Nausea and vomiting
  • Muscular twitching
  • Sleepiness
  • Throbbing in the temples
  • Weakness

If you or anyone else in your motorhome experiences these symptoms, it is necessary that they immediately get to fresh air. Seek medical attention if the symptoms continue. Turn off the vehicle’s engine and/or the generator and avoid restarting them until they have been inspected or repaired by a professional.

In Conclusion
To ensure that you retain the freedom that being able to boondock in your RV provides, it is important to fully understand and be able to maintain your generator. By periodically servicing it, you can save yourself thousands of dollars and hundreds of hours of frustration. Make sure to exercise it regularly and change out the oil and filters to keep it purring like a kitten. This way, you can park miles away from society and experience the peace and quiet that the great outdoors provides.

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