Replace the air filter by locating it on the side or top of your engine, unclipping or unscrewing the cover, sliding out the old filter, and installing a new one in the same direction
A Briggs and Stratton air filter traps dust and debris before they reach your engine. When it clogs, your mower or small engine runs rough, starts hard, or uses more fuel than normal. Replacing it takes about five minutes and costs between $8 and $25 for the filter itself.
The exact steps depend on whether your engine has a cartridge filter (the most common type on newer equipment) or a foam filter (older or specialty models). Both are straightforward — you do not need special tools, and the filter slides or clips in place without fasteners.
Key Takeaways
- Briggs and Stratton air filters are located on the side or top of the engine under a plastic or metal cover held by clips or bolts.
- Cartridge filters (pleated paper) are the standard on most current models and slide straight out and in without tools.
- Foam filters, found on some older or commercial models, can be cleaned and reused or replaced depending on condition.
- You should check your air filter every 50 hours of use and replace it when it looks gray or clogged with dust.
Locate the air filter cover on your engine
The air filter sits in a plastic or metal housing on the side or top of your Briggs and Stratton engine. Look for a black or gray box roughly the size of a soda can, usually near the carburetor or fuel tank. On walk-behind mowers, it is often on the side of the engine facing outward. On riding mowers or larger equipment, check the top or side of the engine block.
The cover is held on by either spring clips (two metal arms that hook over tabs) or bolts (usually one or two). If you see clips, you can remove the cover by hand. If you see bolts, use a socket wrench or adjustable wrench to loosen them — you do not need to remove them completely, just loosen enough to lift the cover away.
Remove the old filter
Once the cover is off, you will see the filter itself. On cartridge filters, it looks like a pleated white or yellow paper cylinder, sometimes with a rubber seal on one end. On foam filters, it looks like a sponge. The filter may be sitting loose in the housing or held in place by a center post (a rod running through the middle).
Slide the filter straight out. If it is stuck, wiggle it gently side to side — do not force it or you risk tearing it. If your filter has a center post, the filter slides off the post as you pull it out. Set the old filter aside; do not reuse it.
Clean the filter housing before installing the new one
Before you put in a new filter, wipe out the inside of the housing with a dry cloth or paper towel. Dust and debris collect inside, and if you do not remove them, they will bypass the new filter and go straight into your engine. Use your finger or a cloth to wipe the walls and the bottom of the housing, and check the center post (if there is one) for cracks or damage.
If the center post is cracked or loose, do not install a new filter yet — contact a dealer or small engine repair shop, because a damaged post can let unfiltered air into the engine. If everything looks intact, you are ready to install the new filter.
Install the new filter in the correct direction
Briggs and Stratton cartridge filters have a rubber seal on one end. This seal must face downward (toward the engine) so it creates an airtight fit against the housing. The pleated paper side faces outward. If your filter has a label or arrow printed on it, follow the direction shown.
Slide the new filter onto the center post (if there is one) or into the housing. Push it down until the rubber seal sits flat against the base. The filter should fit snugly but not require force. If you are using a foam filter, the same rule applies — the sealed end goes down, and the open or textured side faces the air intake.
Reattach the cover and check the seal
Place the cover back on the housing and find it. If your cover uses clips, hook them back over the tabs until they are snug. If it uses bolts, hand-tighten them first, then use your wrench to snug them down — they should be tight enough that the cover does not move, but you do not need to crank hard on them.
Once the cover is on, run your finger around the edge where the cover meets the housing. You should not feel any gaps. If you do, loosen the bolts or clips slightly and reseat the cover, then tighten again. A loose cover lets unfiltered air bypass the new filter and defeats the purpose of replacing it.
When to replace your air filter
Check your air filter every 50 hours of engine use, or at the start of each season if you use your equipment less frequently. A clean filter is white or light yellow. A filter that looks gray, brown, or caked with dust is ready to be replaced. If you run your equipment in very dusty conditions — mowing a dry lot or working in sandy soil — check it more often.
Some Briggs and Stratton engines have a foam pre-filter wrapped around the cartridge filter. If yours does, clean the foam by tapping it gently to dislodge dust, or rinse it with water and let it dry completely before reinstalling. Replace the foam if it is torn or falling apart. The cartridge filter underneath still needs to be replaced on schedule.
Frequently Asked Questions
Can I clean and reuse a cartridge air filter?
No. Cartridge filters are designed to be replaced, not cleaned. Tapping or blowing out a cartridge filter can damage the pleats and create small holes that let dust through. Foam filters can sometimes be cleaned and reused, but cartridge filters should be discarded and replaced with new ones.
What happens if I run my engine without an air filter?
Dust and debris will enter the engine and damage the cylinder walls, piston rings, and valves. This causes rough running, loss of power, and eventually engine failure. Always run with a filter in place, even temporarily. If your filter is damaged, install a new one before using the equipment.
Do I need to drain the fuel tank before replacing the air filter?
No. The air filter is separate from the fuel system, and replacing it does not require draining anything. You can replace the air filter with fuel in the tank. Just make sure the engine is off and cool before you start.
How do I know which replacement filter to buy?
Look at your equipment's model number — usually stamped on the engine block or printed on a label on the frame. Write down the model number and take it to a Briggs and Stratton dealer, a lawn mower shop, or search it online. Filters are model-specific, so using the correct number ensures the filter fits and seals properly.
Can I use a different brand of filter on my Briggs and Stratton engine?
Yes, as long as it is designed for your specific engine model. Aftermarket filters from reputable manufacturers work fine and often cost less than OEM filters. Check the packaging to confirm it fits your model number. Avoid very cheap filters from unknown brands, as they may not seal properly.