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Tips for RV generator maintenance and preventative care

Posted by Cummins Expert on

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Tips for RV generator maintenance and preventative care.

Good RV life and a healthy generator go hand-in-hand. Keeping your generator in tip-top shape is an essential part of RV maintenance. Before you head out on the road, here are a few tips for keeping your Onan generator humming smoothly.

Dig out the owner’s manual.

There’s important stuff in there, such as where to check the oil (Onan models differ in how and where to check the dipstick). There are also important service intervals and troubleshooting tips. Know what you have, how it works, and how to check it. (Lost your manual? Find it online.)

Establish a monthly routine.

Like people, dogs, and cars, generators need regular exercise and run time. Before your next outing, and at least once a month thereafter, run the generator under load, meaning a minimum of 50 percent load capacity (2,000 watts for a 4.0kW generator). Running some appliances, a couple of roof air conditioners or heaters, and the water heater should do the trick.

Eyeball any tubes, vents or screens allowing outside air into the compartment and remove any accumulated debris. Blocked cooling vents lead to overheated generators, especially in the warm summer months. If your generator is liquid cooled, make sure the radiator is clear of leaves and dirt, and check the coolant level.

Pull out the air cleaner and lightly tap it to dislodge any caked chunks of dirt. This will improve its function until time to replace it—usually after 100 hours. (Note: if dusty conditions are the norm, you may need to replace the air cleaner more often.) Don’t try to clean the air cleaner with water or solvents—this will only deteriorate the paper filter and damage your generator.

If you’re pulling your RV out of storage, check for difficulty starting, engine surging, or abnormal run speeds. This could be a sign of old fuel buildup, which will require professional service. To prevent future buildup, use a fuel treatment and exercise the generator for the recommended time and load before over-wintering or storing for an extended period.

Tips for the long haul–A checklist for every 100 hours.

Most manufacturers recommend oil and air filter changes every 100 to 150 hours. Our custom maintenance kits travel with you and include genuine Onan parts for basic maintenance (two quarts Onamax oil, filters, and spark plugs). It’s also a good idea to have a small toolbox that stays with your RV for routine service and fixes. Here’s a quick run-down of what’s needed at around 100 hours (again, check your owner’s manual for specifics):

  • Replace the air filter.
  • Replace the spark plug (may do this sooner if you see signs of carbon buildup or oil fouling). Unless otherwise specified, set it at a .025-inch gap. Make sure the seating surface is clean.
  • Change the oil and filter.
    • Run the generator at half load for about 30 minutes to warm the oil.
    • Shut it off, remove the drain plug, and completely drain the crankcase.
    • Remove the oil filter, if you have one, and clean the area where the filter gasket sits.
    • Pre-fill the new filter with the correct weight oil and dress the gasket with clean oil and install it. Tighten the filter another half turn past contact.
    • Replace the drain plug, or close the drain valve, and fill the crankcase with the right amount and weight of new oil.
    • Run the generator for a few minutes to check for leaks.
  • Check mounting bolts for tightness and secure any that are loose.
  • Check all electrical connections for tightness and corrosion.
  • Check the ignition points if your generator doesn’t have an electronic ignition system. (Be sure to disconnect the negative battery cable first, to prevent an accidental start.)
    • Open the points and ensure contact surfaces are clean and smooth. If there are signs of carbon buildup, burning or pitting, the points should be replaced.
    • Check the point gap (refer to the owner’s manual for proper spacing). If you see a problem, you’ll likely need professional service.
  • Check rubber fuel supply lines for cracks and damage. Thoroughly inspect the lines underneath the RV, where leaks often go unnoticed.
  • Diesel generators must have the water drained from the fuel system annually or every 100 hours of run time. The coolant, thermostat, and radiator caps need to be replaced every two years on diesel models as well.

To infinity and beyond–every 400 to 500 hours.

Your owner’s manual will have recommendations for longer-term maintenance, but in general, fuel filters should be changed every 400 to 500 hours. (A fuel filter is included in our maintenance kits.) It’s a good idea to check slip rings and brushes, the exhaust system, voltage, linkage and carburetors, as adjustments for each of these change over usage time. Changes in run speed (faster or slower) can indicate problems with any of the above.

Log it so you don’t forget it.

One of the best things you can do is log your maintenance and run hours so you never miss an inspection or service. A small notebook or the notes app on your smartphone will do the trick. 50 and 100 hours accumulate faster than you think.

Enjoy the road.

Staying ahead of maintenance and keeping a regular check on your generator’s overall health is key to long hours of happy RV life. Follow the tips and checklists above and keep one of our custom maintenance kits handy. Your Onan generator will thank you and should keep you running worry-free.


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