What to Check When Buying a Used Lawn Mower
A used lawn mower at the right price is a genuinely good value. The same machine sold at the wrong price, or with undisclosed mechanical problems, is an ongoing maintenance burden. The difference between the two is knowing what to inspect before handing over the money. This guide covers the specific checks for walk-behind push mowers and riding mowers that reveal condition, identify red flags, and give you a basis for negotiating price.
Before the Inspection: Ask the Seller
Before inspecting the physical machine, ask three questions:
When was it last serviced? A mower with a recent oil change, new air filter, and sharpened blade has been cared for. One that has not been serviced in three or four years needs immediate investment regardless of how it looks.
Does it start on the first or second pull (or turn of the key)? A healthy, well-maintained mower starts easily. “It starts after a few pulls” can mean a tune-up is needed. “It needs work” is a significant warning.
Why are you selling it? Legitimate reasons (upgrading to a larger machine, moving to a smaller property, switching to battery power) suggest the equipment was functional when taken out of service. Vague answers warrant closer inspection.
Walk-Behind Push Mower Inspection
Engine Condition
Check the oil. Pull the dipstick and look at the oil on it. Clean oil is amber or light brown. Very dark brown or black oil that has not been changed in a long time suggests poor maintenance. Milky or foamy oil indicates water contamination, which is a serious problem.
Inspect the air filter. Remove the air filter cover. A paper filter that is solid gray-black with dirt and debris has been neglected. A foam pre-filter that is coated with oil and debris tells the same story. Both are inexpensive to replace, but their condition reveals how the machine was maintained overall.
Look for oil leaks. Inspect around the base of the engine, around the crankshaft seal where the blade connects to the engine, and along the oil fill port for any dark oil staining or buildup that indicates chronic leaking.
Start the engine and listen. A healthy small engine starts within one or two pulls and runs smoothly without unusual noise. Excessive knocking, rattling, or smoke from the exhaust indicates internal wear. Blue smoke indicates burning oil (worn piston rings or valve seals). White or gray smoke on initial start-up that clears quickly is normal; smoke that persists for more than 30 seconds after warm-up is not.
Blade and Deck
Inspect the blade. Remove or closely inspect the blade (tip the mower carefully with the air filter side up to prevent oil drainage into the air filter). Look for: deep nicks and gouges in the cutting edge, bends or twists along the blade length, cracks at the center hole, and whether the blade is balanced (one side noticeably heavier than the other).
A blade with minor edge nicks can be sharpened. A bent, cracked, or severely unbalanced blade must be replaced ($15 to $30 for most models). An unbalanced blade causes vibration that damages crankshaft bearings over time.
Check the deck for damage. Rust on the deck surface is cosmetic and expected on an older mower. Through-rust (holes or significant thinning) weakens the deck structure. Look at the underside of the deck for crack lines, patches, or areas of obvious repair.
Inspect the wheels. Check that all four wheels are firmly attached, that the axle bolts are not stripped, and that the wheels roll freely. Seized or wobbling wheels affect mowing quality and the load on the drive system on self-propelled mowers.
Self-Propelled Drive System
For self-propelled mowers, engage the drive while the mower is running and verify that it moves under its own power smoothly. The drive should engage fully when the handle lever is pressed and disengage cleanly when released. Weak drive, slipping, or grinding during engagement typically indicates a worn drive belt or damaged drive wheels ($15 to $40 to repair) rather than a major engine problem.
Riding Mower Inspection
Battery and Electrical
The battery is the most common failure point on stored riding mowers. Test voltage with a multimeter: a fully charged 12-volt battery reads 12.6V or higher. A reading below 12V indicates a discharged or failing battery. Ask to start the mower cold (not pre-warmed). If the starter cranks slowly or fails to engage, the battery is likely failing.
Engine Oil and Condition
Check engine oil level and condition as described for push mowers. Also inspect the oil filter (most riding mower engines have full oil filtration): a filter that has not been changed in several seasons is not necessarily a dealbreaker but reduces confidence in the maintenance history.
Deck and Blades
Request that the seller engage the cutting deck while the engine is running. Listen for excessive noise from the deck spindles (a loud grinding or rattling suggests failing spindle bearings, which cost $30 to $80 each to replace and require complete blade removal). Watch whether the deck runs smoothly without vibration. Inspect the deck belt visible through the underside of the deck for cracking, glazing, or fraying.
Drive System and Transmission
For a tractor: engage the drive and move the mower forward and backward. The transmission should shift smoothly without grinding and hold the mower on a slight incline when stopped. For a hydrostatic transmission, loss of power under load or slow acceleration suggests internal wear.
For a zero-turn: both drive levers should engage at the same rate for straight tracking. A mower that pulls to one side with levers in the same position has a tracking issue in one hydrostatic motor.
Tire Condition
Check tire sidewalls for cracking, which indicates UV degradation and age. Check that all four tires hold pressure. A mower with multiple slow-leaking tires has been stored neglected. Front tire wear patterns can also indicate frame or spindle alignment issues.
Price Calibration
A push mower in good working condition with known recent maintenance at half to two-thirds of the equivalent new model’s retail price is generally a fair value. A riding mower with documented service history, clean oil, good blade condition, and a confirmed start is typically worth 40 to 60% of new retail depending on age and hours of use.
Walk away from any machine the seller will not start for inspection, or where the engine has obviously been tampered with (freshly cleaned engine on an otherwise dirty machine, non-original spark plug on a machine the seller claims was serviced recently) without a clear explanation.