Generator Air Filters: Cleaning and Replacement

What the air filter does

Every engine that burns fuel draws air in along with the fuel. An air filter sits in that intake path and catches dust, dirt, pollen and other debris before they get into the engine. On a generator listing, the air filter is not usually named as a feature; it is a standard part of the engine, described in the maker's manual. The manual also names the replacement part number and lists the filter in the maintenance schedule.

This article explains the general idea so you can read your manual with the right questions. The manual, not this article, is the instruction for your specific unit. If a listing or the maker's page mentions a washable filter or a disposable element, that detail belongs to that model only. When you shop, the portable generator guide explains what a listing does and does not state about the engine.

Clean or replace: read the manual first

The filters that come on portable generators are not all the same. Some are foam or paper elements that the manual says to clean; others are disposable elements that the manual says to replace on a schedule. The difference is stated in the owner's manual for the model, sometimes on the maker's page for the unit.

The maintenance guide lists the care topics the manual covers. For the air filter specifically:

• Look for the maintenance section in the owner's manual.
• Find the air filter in the parts list; the manual gives the replacement part number.
• Order the replacement from the maker's parts page, not from a generic substitute.
• If the manual shows a cleaning step, use only the method the manual describes.

Where the filter sits

On most portable generators, the air filter sits in a small housing on the engine, usually under a cover held by a clip or a screw. The manual shows the location with a diagram. On an inverter generator, the housing is usually in the same place, inside the case, and the manual explains how to reach it.

A listing may not show the filter at all, so the manual is the source for this part. A dual fuel or tri fuel unit uses the same filter for both fuels because the intake is the same side of the engine.

Cleaning the element

When the manual says the filter can be cleaned, it describes the method for that element. A foam element is often cleaned by washing it in the solution the manual names, rinsing it, and letting it dry completely before reinstalling it. A paper element is usually not washed; the manual may describe tapping it gently to knock off loose debris. Whatever the manual says, follow it exactly.

Never oil, oil-soak or treat an element unless the manual says the element is an oiled type. Work on the filter only when the engine is off and cool, as the manual states.

• Set the element on a clean surface and keep the housing opening covered while it is out.
• Reinstall the element only when it is dry and in the same position the manual shows.
• Keep the old element until the new one is fitted and the housing cover is back on.

Replacing the element

When the manual calls for a new element, match the part number in the manual's parts list. The replacement filter comes in the maker's packaging with the maker's part number on it. Remove the old element, wipe the housing with a clean cloth, and fit the new element exactly as the manual's diagram shows.

A used generator may come with a filter that is not the maker's part. If the filter does not match the housing, order the maker's part before running the unit. The manual and the maker's page are the source for the correct part number.

When the manual says to do it

The owner's manual lists the maintenance schedule: how often to check the filter and how often to clean or replace it. The schedule is stated in the manual, not in a listing. The hour meter on a generator, when the model has one, helps you track run time against that schedule.

In dusty work sites or during storm cleanup, the manual may suggest checking the filter more often. Write the date and the hour reading on the filter box or in a note so you can find it later.

Keeping the reading matter

Keep the owner's manual, the parts list and the packaging for the unit. The manual lists the air filter part number, the maintenance schedule and the cleaning method. When you buy a generator, keep the manual with the unit, not in a drawer elsewhere.

For a used generator without a manual, contact the maker; the maker's site usually publishes manuals for current and older models. Oil changes are a separate manual-led job, covered in the oil change guide, and the filter is handled the same way: read the manual first.

Before you run the generator

Maintenance happens in the garage or yard, but running the generator is a different matter. Read the carbon monoxide pages published by the CPSC, the CDC and the EPA before you start any generator, and read the maker's guidance for the unit. The manufacturer's manual is the instruction for the model; the safety pages explain the general hazard.

When you pick a generator, start with the best generator guide, then read the manual for the unit you choose. The air filter is one part of the care routine the manual lists.

What to pick for your situation

Questions

Do generators all have the same air filter?

No. Filters differ by model: some are foam, some are paper, some are washable, some are disposable. The owner's manual for the model, not a general guide, states which type is fitted and the part number.

Can a paper air filter be washed?

Usually not. The manual describes the method for the element on that model. If it says the element is washable, follow that method; otherwise replace it with the maker's part.

Do I need to check the air filter on a new generator?

Yes. The manual lists the maintenance schedule for a new unit, including when to check the filter. Read that section before the first run, and keep the manual with the generator.

What does the hour meter have to do with the air filter?

The hour meter records run time, and the manual's schedule is often expressed in hours. On models with an hour meter, you can compare the reading to the schedule.

Where do I buy a replacement filter?

From the maker's parts page, using the part number in the manual. A filter that is not the maker's part may not match the housing on your unit.

Is cleaning the air filter a repair?

Cleaning and replacing the filter is a maintenance step the manual describes, not an engine repair. If the manual calls for opening the engine or the carburetor, that work belongs to a qualified service dealer.