Lawn Mower Tune-Up Checklist and Cost

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Last updated October 28, 2026 · Applies to: lawn mowers from Toro, Husqvarna, Honda, Troy-Bilt, John Deere and Craftsman and others

Step 1: Change the oil

Step-by-step instructions for this step are being written.

Engine oil system (splash-lubricated): Fill cap / dipstick → Crankcase → Dipper / slinger → Breather → Drain plug → Low-oil sensorFill cap / dipstickcheck levelCrankcasecapacityDipper / slingersplashes oilBreathervents crankcaseDrain plugor tip to drainLow-oil sensorsome engines
Engine oil system (splash-lubricated). Too much oil can be pushed into the breather and burned; too little seizes the engine.

Step 2: Replace the spark plug

Step-by-step instructions for this step are being written.

Ignition path: magnet to spark: Flywheel magnet → Ignition coil → Stop / kill wire → Plug lead & boot → Spark plug → CombustionFlywheel magnetkey aligns timingIgnition coilair gap to flywheelStop / kill wiregrounds coilPlug lead & boottight fitSpark pluggap + conditionCombustionspark ignites mix
Ignition path: magnet to spark. Test the end of the chain first: a spark tester on the plug lead.

Step 3: Replace the air filter

Step-by-step instructions for this step are being written.

Air intake path: Air filter cover → Pre-filter / foam → Paper filter → Carburetor throat → Intake gasket → CylinderAir filter coverclips / screwPre-filter / foamclean, oiledPaper filternot oil-soakedCarburetor throatchoke plateIntake gasketno air leaksCylinderintake valve / port
Air intake path. A restricted filter richens the mixture; a leak after the carburetor leans it out.

Step 4: Sharpen and balance the blade

Step-by-step instructions for this step are being written.

Mower blade mounting: Crankshaft → Flywheel key → Blade adapter → Blade → Blade boltCrankshaftvertical shaftFlywheel keyshears on impactBlade adapterdrive hubBladeedge + balanceBlade bolttorque to spec
Mower blade mounting. Always disconnect the spark plug lead before touching the blade.

Step 5: Clean the deck and check belts and cables

Step-by-step instructions for this step are being written.

Blade-brake bail and safety stop: Bail handle → Control cable → Brake arm → Stop switch → Ignition coilBail handleheld against barControl cableadjust slackBrake armon flywheelStop switchgrounds coilIgnition coillive when bail held
Blade-brake bail and safety stop. Releasing the bail grounds the ignition and brakes the blade. A stretched cable keeps it grounded.

Step 6: Check fuel and carburetor

Step-by-step instructions for this step are being written.

Fuel path: tank to cylinder: Fuel tank → Cap vent → Shut-off valve → Fuel filter / line → Carburetor bowl → Main jet → Intake → cylinderFuel tankfresh fuelCap ventlets air inShut-off valveopen?Fuel filter / lineno cracksCarburetor bowlfloat + needleMain jetmeters fuelIntake → cylinderfuel + air
Fuel path: tank to cylinder. Fuel must flow through every stage. A blockage at any box starves the engine.

Brand notes

Brand-specific notes for Toro, Husqvarna, Honda and Troy-Bilt are being researched.

When to take it to a shop

Hand it over if the engine still will not run after the fuel, spark and air checks, if you find metal in the oil or the engine is seized, or if the machine is under warranty (opening it yourself can void it).

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Frequently asked questions

Answers being written: What is included in a lawn mower tune-up? · How often does a mower need a tune-up? · How much does a shop tune-up cost? · Can I do a tune-up myself?