Understanding basic lawn mower repairs can extend its life and save money. Many common issues are resolvable at home with fundamental knowledge and the right tools. This guide provides steps for basic fixes.
Essential Safety Measures
Prioritizing safety is essential before working on a lawn mower. Always disconnect the spark plug wire to prevent accidental starting. Allow the engine to cool completely, as parts can become very hot.
Wear heavy-duty gloves and eye protection to safeguard against sharp blades, hot surfaces, and flying debris. Ensure the mower is on a stable, flat surface to prevent tipping during repairs.
Diagnosing Common Lawn Mower Problems
Identifying the issue with your lawn mower starts with observing its symptoms. If the mower fails to start, check for an empty fuel tank, old fuel, or a loose, dirty, or disconnected spark plug. A dirty air filter can also restrict airflow.
If the mower starts but quickly dies, it may be due to a clogged fuel filter or carburetor issues, often caused by old gasoline. Rough running can also stem from a dirty spark plug, a clogged air filter, or an imbalanced fuel-to-air mixture. Excessive smoke often indicates an oil-related problem, such as an overfilled reservoir, spilled oil on hot parts, or an oil leak. White or bluish smoke points to oil burning, while black smoke suggests the engine is running too rich with fuel, often due to a dirty air filter or carburetor issue.
An uneven cut can be caused by dull or unbalanced blades, uneven tire pressure, or a misaligned mower deck. Inspect the blade for damage or dullness and check tire inflation.
Step-by-Step Basic Repairs
Addressing common lawn mower problems often involves straightforward repairs.
Spark Plug Replacement
Replacing a spark plug is a good starting point for starting issues or rough running. After disconnecting the spark plug wire, use a spark plug socket to remove the old plug. Check the gap on the new spark plug to match your mower’s specifications before hand-threading it in and tightening until snug.
Air Filter Maintenance
Cleaning or replacing the air filter is another simple fix for performance issues. Locate the air filter housing, remove the old filter, and either clean it if reusable or replace it with a new one, ensuring a proper seal.
Carburetor Cleaning
For carburetor issues, especially those caused by old fuel, cleaning involves removing and disassembling the carburetor. Clean out any gummed-up fuel passages with carburetor cleaner.
Blade Sharpening or Replacement
Sharpening or replacing the blade is important for an even cut. Disconnect the spark plug, then tilt the mower on its side with the carburetor facing upward to prevent fuel leaks. Secure the blade with a piece of wood or a C-clamp. Use a socket wrench to remove the mounting bolt by turning it counter-clockwise.
Sharpen the blade with a file or grinder, maintaining the original angle for a “butter-knife” sharp edge, and balance it before reinstallation. Replace the blade if it is bent or severely damaged. When installing a new blade, ensure correct orientation and tighten the mounting bolt firmly.
Fuel Filter Replacement
Checking and replacing the fuel filter is important for fuel delivery problems. Locate the inline fuel filter between the fuel tank and the carburetor. Use clamps to stop fuel flow before disconnecting the fuel lines and installing a new filter in the correct direction.
Routine Maintenance for Longevity
Regular maintenance extends a lawn mower’s lifespan and prevents breakdowns.
Engine Oil Change
Change the engine oil annually or every 50 hours of use. Warming the engine slightly before draining helps remove contaminants. Refill with the correct type and amount of fresh oil as specified in your mower’s manual.
Mower Deck Cleaning
Keep the mower deck clean after each use to prevent caked-on grass clippings, which reduce airflow, cause uneven cuts, and lead to rust.
Rinse with a hose.
Use a deck wash port.
Scrape by hand after disconnecting the spark plug and tilting the mower.
Thoroughly dry the deck after cleaning to prevent corrosion.
Fastener Inspection and Storage
Regularly inspect and tighten fasteners to prevent components from loosening due to vibration. Proper off-season storage protects the machine from degradation. This includes draining fuel or adding a stabilizer, cleaning the mower, and removing the battery.
Deciding When to Seek Professional Help
While many lawn mower issues are DIY resolvable, some situations require professional assistance.
Complex Starting Problems
If persistent starting problems continue after checking fuel, spark plug, and air filter, it may indicate complex issues. These include fuel line blockages, carburetor problems, or ignition system failures requiring a trained technician.
Unusual Noises or Overheating
Unusual noises like grinding, knocking, or excessive vibrations can signal internal engine problems, a bent crankshaft, or damaged bearings. Engine overheating is another concern, potentially pointing to cooling system malfunctions and leading to damage if ignored.
Specialized Repairs
Transmission issues in self-propelled mowers or electrical problems in battery-powered models often require specialized tools and expertise. Consider the repair cost versus a new mower’s price. If the repair cost is a significant percentage of a new unit, or if your mower is old (beyond 7-10 years) and frequently needs repairs, replacement might be a better decision.