How do I keep my lawn mower from breaking down?
Keep fuel fresh, change the oil, replace the air filter and spark plug on schedule, keep the blade sharp and clean the deck after mowing. Those five habits prevent most breakdowns. Follow the intervals in your owner's manual, and disconnect the spark plug wire before any work near the blade.
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By Kasra Taheri, Founder, LoclisPublished
Researched and drafted with AI, then checked claim by claim against the sources listed below before it was published. Prices and rules change; the dates beside each source say when it was last checked.
Step by step
Read when to stop and call a pro, further down this page, before you start.
Step 1: Disconnect the spark plug wire
Pull the wire off the plug before any maintenance near the blade or engine.[1]
Step 3: Use fresh fuel
Buy only what you will use soon, and add fuel stabilizer if the mower will sit for more than a few weeks.[2]
Step 4: Replace the air filter
Replace a dusty filter, and change it at least once a year.[3]
Step 5: Change the spark plug
Inspect the plug each season and change it about every two years, using the type and gap in the manual.[3]
Step 7: Clean the deck
After mowing, scrape or blow off the clippings stuck under the deck.[3]
Step 8: Store it properly
At the end of the season, deal with the fuel as the manual directs and keep the mower dry.
Five habits that prevent most breakdowns
Most mower failures are not sudden. They come from stale fuel, dirty oil, a clogged air filter, a tired spark plug or a dull blade, all of which are cheap to prevent. The manufacturer's schedule is the baseline; Virginia Cooperative Extension's mower-safety advice includes the instruction to perform routine maintenance as recommended by the manufacturer.[1] The habits below are what that looks like in practice.
Before any of it, pull the spark plug wire off the plug. Virginia Cooperative Extension says to disconnect the spark or electric plug before troubleshooting or repairing the mower.[1] That keeps the blade from turning if someone pulls the cord.
Oil
Oil is the easiest habit to keep. Briggs & Stratton's advice is to check the oil level regularly - ideally every time you mow.[4] Do it with the engine cold and the mower level, and top up to the fill line.
Change it on schedule. Illinois Extension says that for most residential lawnmowers, oil is typically changed every year.[3] Briggs & Stratton gives an hours-based version: after the first change, change the oil after every 50 hours of use or at the beginning of each lawn care season.[4] If you mow a large property, go by the hours. Take used oil to a recycling collection point rather than pouring it out.
Fuel
Stale fuel is a common reason a mower will not start in spring. Briggs & Stratton says gasoline deteriorates after 30 days and can negatively affect engine and starting performance.[4] Buy gasoline in small amounts, keep it in a labelled container made for it, and do not let a full can sit through the winter.
For a mower that will sit, Penn State Extension's advice is to add fuel stabilizer if the equipment will be idle for more than a few weeks, and avoid keeping stored fuel for long periods of time.[2] If the mower has a fuel filter, Illinois Extension says fuel filters are typically changed on an annual basis.[3]
Air filter and spark plug
A mower breathes through its air filter, and Illinois Extension notes it fills with dust and debris over time.[3] Replace it at least once per year, or sooner after mowing in dry, dusty conditions. A new filter is among the cheapest parts you can buy.
The spark plug is next. Look at it at the start of each season, and the rule of thumb from Illinois Extension is that plugs are typically changed every two years.[3] Fit the plug type and gap your manual lists.
Blade and deck
A sharp blade is good for the mower as well as the lawn. Illinois Extension says dull blades tear grass and leave ragged wounds that are harder to heal.[3] A blade also needs to stay balanced, because an unbalanced blade can wobble, strain the mower and cut unevenly.[3]
Sharpening is optional DIY. Briggs & Stratton notes that your lawn mower dealer can sharpen blades for you,[4] and for many owners that is the safest choice. If you do it yourself, the spark plug wire stays off throughout.
Cleaning matters too. Illinois Extension warns that clippings stuck to the underside of the deck hold water, rust the metal and shorten the mower's life.[3] After mowing, turn off the engine and keep the spark plug wire off, then scrape the deck with a putty knife.[1][3] Never use your hands or feet to clear clumps.[4]
Off-season storage
Before storing the mower, deal with the fuel as your manual directs, either by stabilizing it or running the tank down, then clean the deck and keep the mower dry. A mower that goes into storage clean and on fresh oil is the one that starts first pull in April.
Stop and call a pro if
- The engine smokes, knocks or surges. These are signs of a problem beyond routine maintenance.
- Oil or fuel is leaking. Stop using the mower until the leak is traced.
- The blade is bent, cracked or has hit something solid. Do not run it; have a shop inspect the blade and the crankshaft.
- The mower is hard to start even with fresh fuel and a new plug. The carburetor likely needs cleaning or rebuilding.
- You are not comfortable tipping or working under the mower. Have a shop do the service.
Getting help in Virginia
If it already will not start, see why a lawn mower won't start and how to fix a lawn mower that won't start. For a yearly tune-up quote, what a small engine shop charges to fix a lawn mower explains the cost drivers. Browse small engine repair answers or find local mower repair pros.
When you are ready, describe the mower and local small engine shops can quote it.
Common questions
- How often should I change my mower's oil?
- Illinois Extension says that for most residential lawnmowers, oil is typically changed every year. Briggs & Stratton says to change it after every 50 hours of use or at the beginning of each lawn care season, with a first change after five hours on a new mower. Your owner's manual has the exact interval and oil type.
- How long does gas last in a mower?
- Not long. Briggs & Stratton says gasoline deteriorates after 30 days and can negatively affect engine and starting performance. Buy small amounts, and add fuel stabilizer if the mower will sit for more than a few weeks.
- Do I really need to sharpen the blade every year?
- Illinois Extension says sharp blades cut grass, while dull blades tear it and leave ragged wounds that are harder to heal. Many owners sharpen once a season or when the cut looks ragged. A dealer can do it, and the blade should be balanced afterwards.
- How often should I change the spark plug and air filter?
- Illinois Extension says spark plugs are typically changed every two years, and air filters at least once per year. Check your manual for the plug type and gap.
- Is it worth getting a yearly service from a shop?
- It can be if you do not want to do the work yourself, or you rely on the mower for a large property. Ask what the service includes, such as oil, filter, plug and blade, and get the work itemised in a written quote.
Sources
- [1] Lawn Care: Rotary Mower Safety (BSE-42P), Virginia Cooperative Extension, Virginia Tech. Checked October 27, 2026.
- [2] Fuel Ethanol: Hero or Villain?, Penn State Extension. Checked October 27, 2026.
- [3] Mower Maintenance, University of Illinois Extension. Checked October 27, 2026.
- [4] How to Perform Lawn Mower Maintenance, Briggs & Stratton. Checked October 27, 2026.
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