Tech Tips – Important Generator Maintenance


For boondocking purists such as we are, it seemed impossible that we’d ever have a generator on an RV. Maybe we wouldn’t have, had it not been that a truck camper we picked up came equipped with one.

We’re almost embarrassed to note that having the generator has proved to be a fine thing. We don’t use it for long periods of time—we still rely heavily on solar—but it has come in handy pretty often. However, having a generator is like having a pet—you’ve got to take care of it, or you’ll learn to regret it. Happily, it’s not difficult to handle simple generator maintenance.

Regularity is really the key to generator maintenance. That’s not too difficult when you’re regularly using a generator—the problem is in the “offseason.” Generators are like a lot of dogs: They want exercise!

This means, when translated, that you should “exercise” your generator every month. Yep, once a month, every month, your generator needs your attention. This simply means firing it up, putting on a fair-sized load (your air conditioner set to cool), and running it for an hour.

But even before you hit the start switch, take a moment to check out your engine oil level. How do you check the dipstick? It can be a bit confusing. Our rig’s Onan generator places the dipstick in the oil filler tube.

Onan generator. Photo via

It was a bit of a puzzlement at first: Do we check the oil level with the dipstick screwed in tight? Nope, in our case, we have to push the stick into the shoulder of the filler tube. But other Onan generators require the level be checked with the cap screwed in all the way. Check out your owner’s manual.

Here’s an interesting point for those new to RV generators: Some of these little power plants have a safety system installed. Let the oil level get too low, and the generator won’t start, or will “cut out.” But don’t rely on that, run low on oil and you risk severe—and costly—damage. It’s a good idea to check out your oil level as part of your monthly exercise program, and certainly before you head off on an RV outing.

Check on cooling

Next on the regularity list? On your monthly exercise program, take a glance at the air inlet system. We’re not speaking of the air filter, but rather, any tubes, vents or screens that allow outside air into the generator compartment.

Most RV generators are air-cooled, and if debris blocks the cooling vents, an overheated generator can result. If your generator has a liquid cooling system, make sure the radiator is clear of leaves or other junk, and it’s not a bad idea to check the radiator coolant level, too.

Most other “scheduled” maintenance falls under the 50- and 100-hour program, but let’s call this a “general recommendation.” Unless your owner’s manual directs otherwise, typically at every 50 hours of running time, you should remove your air cleaner and lightly tap it against a solid surface to get any big chunks knocked loose.

At the 100-hour marker, bring the toolbox. Pull the air cleaner element back out, and this time, replace it with a new one. The exception here is if you run your genset in dusty conditions—then you’ll probably need to replace it more often. And don’t try to use solvents or water to “clean” the air cleaner element. These paper critters will simply be damaged by such an effort, allowing generator-killing dust to get sucked into the works.

At the century mark, you’ll also need to replace the spark plug (or sooner if it shows signs of carbon buildup or oil fouling). Follow your manufacturer’s gapping recommendation, but lacking one, .025 of an inch is a good start. Before you slip the new plug into the cylinder, make sure the seating surface is clean.


Onan generator. Photo via

Replacing oil

The 100-hour mark is also typically when generator makers require an oil change. Like an oil change on a motor vehicle, you’ll want the oil to be warm. Start the generator and run it at half load for about a half-hour. Shut the generator down, remove the drain plug (or open the drain valve) and completely drain the crankcase. While waiting for the old oil to drain out, remove the oil filter (if so equipped—our genset has no oil filter).

Clean the mating surface where the filter gasket comes in contact with the generator. “Pre-fill” the filter with the appropriate weight of oil, dress the filter gasket with clean oil, spin it down until contact is made, then tighten the filter another half turn. Replace the drain plug (or close the drain valve), and fill the crankcase with the appropriate amount (and weight of) fresh oil. Be sure to start the generator and run it for a few minutes to allow any leaks around the filter or drain plug to manifest themselves.

A few other items should also be checked at this time. Make sure your generator is staying put—check to make sure the mounting bolts are secure. All electrical connections should likewise be checked for tightness (and no corrosion on the battery terminals). If your generator is fueled by something other than LP, chase down the fuel filter; your manufacturer probably has a replacement schedule.

Finally, the 100-hour service is a good time to check the ignition points, assuming your generator doesn’t have an electronic ignition system. You’ll likely find them under a sheet metal cover. Before checking them, it’s best to disconnect the negative battery cable to ensure the genset isn’t accidentally started up while you’re working “under the hood.”

Open the points and examine their contact surfaces. The contacts should be clean and smooth. If there’s a carbon build-up, signs of burning or pitting, the points should be replaced. Point gap is checked with points fully open, and you’ll need to have the specified point gap information, as it varies from generator to generator. Some generator manufacturers recommend that point setting be done by a service technician, as ignition timing may need to be set on some units.

Part of your generator’s maintenance is also the maintenance of good records. It’s good to keep a maintenance log, record the work done and hours shown on the running clock. You’ll rest better knowing you’re keeping up on maintenance, and if and when you sell your rig, the new owner will appreciate your efforts. An online tool such as Maintain My RV will help.

Not only can you keep track of all your generator maintenance, but you can keep all of your RV maintenance history in one place. You’ll also receive email reminders when maintenance is due. Whether you have a small trailer or large Class A motorhome, Maintain My RV can keep track of it all, along with up to two other vehicles, such as a tow car, motorcycle, or four-wheeler.

Russ and Tiña De Maris are authors of RV Boondocking Basics—A Guide to Living Without Hookups, which covers a full range of dry camping topics.  They also provide great resources in their book, Camp Hosting USA—Your Guide to State Park Volunteering.

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