The Complete Lawn Mower Maintenance Guide

The complete lawn mower maintenance guide will outline everything you need to know to properly maintain your lawn mower, and keep it running reliably for seasons to come. By following the information provided, you can avoid the hassles of untimely break downs. First we will begin with the best practices you can cultivate now to prevent future service calls for your lawn mower. Then we will present a general schedule for lawn mower maintenance, to keep that engine purring and blade spinning.

Best Practices to Prevent Service Calls

Tilting your Lawn Mower

If you ever have to tilt your lawn mower on its side it is absolutely imperative that you locate where your lawn mower's intake side is. To do this, look for your unit's air filter. Nearby will be the carburetor. This is where air from outside the lawn mower, is drawn into the machine and filtered, before it makes its way into the carburetor and finally into the combustion chamber within the engine. We always want the air entering to be as clean as possible. When you locate the air filter and carburetor, these two components comprise the intake side, and must always be kept facing up, whenever tilting the lawn mower. Failure to follow this rule will result in potential no starts, hard starts, or improperly running engines. What happens is oil and or gas will spill out from the engine and seep into the air filter and possibly into the carburetor. The carburetor and air filter must always remain clean in order to work properly. Save yourself a lot of hassle and always tilt your lawn mower with the air filter and carburetor side up!

Manage Your Gas

More than 2/3rd's of all small engine related service calls stem from fuel-related problems. When you purchase gas for your lawn mower, try not to buy more than will be consumed within a month's time. Buying large amounts of gas and storing in your garage for extended periods, is a recipe for disaster. The ethanol in the gasoline attracts moisture and what occurs is what is called phase separation. Layers of water form in the gasoline container, or worse in the gas stored in your lawn mower's gas tank. The water in the gasoline wrecks havoc on small engines as water where it shouldn't be can cause corrosion in metal gas tanks, hard or no start conditions or poorly running machines. Store gas safely in an appropriate container, in a dry cool place, as this slows the break down process of gasoline. By simply following the general guideline of buying just enough gas that will be used within two mowing sessions, you can avoid most lawn mower issues.

At Each Gas Fill Up: Inspect the Engine Air Filter

Whenever you fill the gas in your lawn mower, its a great practice to remove the air filter cover and inspect the condition of your engine air filter. If it is dirty, it must be cleaned before reinstalling.

To clean this foam style filter: let soak in dish soap, dry and saturate in clean engine oil, ring out excess by hand squeezing then reinstall

These paper style filters can be cleaned if lightly coated in dust or dirt. Simply tap on a hard surface to remove light dirt and dust. If very dirty or oil/gas soaked, replace. Do not use compressed air to clean!

Look for Blade Obstructions in Mowing Area Prior to Mowing

A great practice before you begin mowing is to survey the lawn for potential obstructions that may come in contact with the spinning blade. Try and prevent collisions with rocks, stones, lawn ornaments, branches, roots etc. If the blade strikes anything hard enough, it can render the machine irreparable, or at least not economically sensible to repair. Bent blades, crankshafts, and sheared flywheel keys are all possible outcomes. A bent blade or crankshaft will cause the unit to vibrate excessively if it is able to start. The excessive vibration will cause the machine to wear considerably faster, and affect mowing performance. If the flywheel key has sheared the machine will be impossible to start, and if the key is partially sheared it will either cause a dangerous starting condition; the pull rope will be yanked out of the operator's hand violently or it will stumble and miss with significant power loss. Avoid all of these conditions and mow carefully looking for objects that may come in contact with the blade.

Clean Your Mower's Deck After Each Use

Grass clippings, and dirt can accumulate on the underside of your lawn mower. It is best to use a putty knife and remove grass clippings before they have had a chance to adhere to the underside of the lawn mower for extended periods of time. If left uncleaned, mower performance will suffer as air cannot be directed properly over the contours designed into the deck's under body. Grass will not be effectively evacuated. Moisture from the grass will begin to corrode and rot the deck. You must never mow with a deck that has holes in it, as objects can be thrown through these holes and harm the operator or bystanders. By simply cleaning underneath your mowers deck, you avoid a rotted deck that is irreparable and would require immediate replacement. Gently scrape away grass clippings using a putty knife; avoid scratching or gouging the metal. It also wouldn't hurt to keep the top side of the deck clean to make it possible to detect potential sources of oil and or gas leaks. Having a unit covered in dirt or grass makes this next to impossible.

Mower under body clear of grass clippings

Keep Your Lawn Mower Out of the Elements

Never leave your lawn mower outside and uncovered for extended periods. Water will begin to accumulate in the gas tank through vent holes built into the gas cap. As explained earlier, the effect of water within a small engine is never good; avoid this problem and keep your mower out of heavy rainfalls.

Check Your Engine Oil Prior to Each Use

Checking your engine oil prior to each use allows you to not only ensure there is an adequate level of oil in the machine before you run it on a low oil condition, it also allows you to assess if the oil level is dropping or rising. Always check the oil on a level surface and allow the engine to sit for 2 minutes before checking if, recently run. Refer to owner's manual to determine of the dipstick is to be threaded into the dipstick hole for accurate readings.

Clean Cooling Fins

Remove engine cover

Clear dirt, grass and other debris from flywheel cooling fins

Clear cylinder head cooling fins as well

Lawn mower engines, like other small engines, are air-cooled. They depend on cooling fins and a spinning impeller/flywheel to circulate air and cool the engine.

When dirt and debris become packed in these cooling fins, they can't perform their cooling function as intended, resulting in an overheated engine. In short, an overheated engine wears out much faster. The solution: always ensure the area beneath the engine cover is free from grass or dirt buildup. The cover is usually secured with a few fasteners, so make sure the engine is off and cool before attempting to remove it.

Lubricate the Blade Brake Bail Cables and Linkages

Its important that you lubricate the metal cables that operate the blade brake bail bar that you must depress in order to start your lawn mower's engine. By spraying a silicone based lubricant into the areas shown, then manually engaging the bar to distribute the lubricant down into the cable, this will prevent seizure of the cable. If allowed to seize, they render the mower inoperable.

Lubricate the blade bail cables with a silicone lubricant as they do not attract dirt

Storing Your Lawn Mower for Extended Periods

It is important that you plan to try and run your lawn mower dry of fuel at the last mowing session. There are fuel stabilizers available if fuel must be left for extended periods. If bowl style carburetor is used, be sure to drain the bowl to remove residual gas, locate the drain at the bottom of the bowl (if equipped.) Attempt to start mower again before storing. Remove spark plug, then remove the plug from the wire. Next, add a few squirts of clean engine oil to the spark plug hole, then gently pull start rope while engaging blade brake bail to distribute the oil to the internals of the engine. Reinstall spark plug by threading into the spark plug hole, tighten using appropriate socket and ratchet. Turn the throttle to off and close the choke (if both are manually operated.) Store the mower in a dry area.

General Preventive Maintenance Schedule

Maintenance Item	Suggested Time Interval
Engine Air Filter	Inspect at gas fill up; clean after 25 hours, (or sooner if used in extreme conditions: tall grass, dusty environment)
Engine Oil	Change every 25 hours
Spark Plug	Inspect every 25 hours, Replace every 100 hours
Cooling Fins	Clean every 50 hours, Reduce to 25 hours if used in extreme conditions: tall grass, dusty environment)
Cables, linkages, wheel height adjustment levers	Lubricate at beginning of each mowing season

By following the general practices explained and adhering to this general maintenance schedule, you can be confident that your lawn mower will run reliably for many seasons to come. If your looking to learn how you can repair, diagnose and be exposed to the fundamentals of small engine theory, enroll in our free online course here: Online Program

Never the Norm!