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How to Maintain a Gas Lawn Mower

Last updated on: February 7th, 2020

Lawn mower maintenance is a very important task and a must do if you want to extend your lawn mower lifetime. Also, mowing with an unsecured lawn mower is dangerous and can damage your machine or even hurt you. In this guide, we will walk you through all important steps that you have to follow in order to keep your lawn mower in better shape. This guide refers to the gas lawn mower maintenance, so if you own an electric lawn mower please check our electric lawn mower maintenance guide.

How to Maintain a Gas Lawn Mower

As you probably already know there are plenty of different ways to take care of your lawn mower. Some maintenance work is done after every use and some others tasks have to be done once or twice per season. Each, even the smallest maintenance has to be done with your lawn mower OFF!

Cleaning after each use

We suggest that you clean your gas lawn mower after every use. Remove any grass residues on and under the mower deck. Residues on mower deck you can remove with your hand (remember to wear a pair of work gloves) and those under mower deck you can remove with a wooden stick. Slightly lean your lawn mower to one side so you could reach under mower deck to remove dirt and grass residue. Doing that, be careful not to cut yourself.

Be careful not to burn yourself if you are cleaning the mower right after its usage – some parts can become really hot while operating. Leave the mower to cool down after using it if you want to check motor or any parts near it. Dirt build-up under your mower deck can make your blade dull over time and you will use more gas for less work because your mower will not work smoothly anymore.

Bag for grass clippings and ventilation system should also be cleaned after mowing. The air filter could get clogged – you will recognize clogged air filter if your mower has difficulties with starting or quickly stops after few seconds. A clogged air filter is the main reason why your lawn mower won’t start. You could also see smoky or oily exhaust if you have problems with air filter.

After each use, you should also check for check all the fasteners (nuts, bolts) and make sure that they are tight. If not, use the appropriate tool (such as ratchet wrench or screwdriver) to tighten them. Check and clean the wheels too since they have to be clean to rotate smoothly. If they are staggering use few drops of oil to lubricate the axis.

Blade maintenance

When you are doing maintenance job like this be sure to remove spark plug lead from the spark plug. Always remove spark plug lead before such repairs. It is also good to know that if you cannot start your mower then first check if spark plug lead is on the spark plug. Otherwise, the gas lawn mower will not work. A blade is usually strongly fastened to the rotor so there is no need of checking or fastening the bolts on the blade. Check them only if your mower rattles.

No matter how good you care for mower deck cleanliness you will need to make the blade sharp again sooner or later. You can buy a new blade or you can sharpen the existing one. Please be very careful while removing the old blade from the mower deck. Although it seems to be dull it can be very sharp so try not to cut yourself. The blade is usually fastened with a bolt in the middle so you will have to unscrew it with a ratchet and six-point socket of appropriate size. If a blade is circling in the same direction you are spinning a ratchet then try to put a wooden piece between blade and mower deck to hold a blade in position. Now when your blade is off the lawn mower inspect where the blade is ruined. If you can repair it use appropriate tool and make it sharp again. Best way to sharpen mower blade is to do that manually with a metal file or with a machine, such as a bench grinder or belt sander. Take care of your protection (gloves, eye protection, long sleeves) while doing this.

After a couple of sharpening cycles, your blade will not be suitable to sharpen it again. At this point, you will have to buy a new one. Remove old blade from your lawn mower and line it with a new replacement blade. Be sure that they are same in size and that holes for bolts are in the same position. Mount new blade in the same orientation and make sure it does not wobble up and down. It has to be firmly fastened. Be sure that clearance between blade and mower deck is the same everywhere around. After the blade is fastened back to its place put your mower back on its wheels, attach spark plug lead back on the spark plug and start the lawn mower. Leave it working on a place for a couple of minutes and carefully listen to the sound of the working lawn mower. If it sounds strange, turn off the lawn mower and find out the reason.

How to drain oil from lawn mower?

You will also have to check lawn mower oil level from time to time. If you have too little oil in the system add some and if your oil is old it is best to remove all of it from the oil fill and replace it with new oil. Remove spark plug lead from the spark plug and slowly lean the lawn mower to the side. Remove oil fill plug and drain oil in an appropriate container for disposal. You should also drain any redundant oil if you have too much oil in the lawnmower. Many new lawn mower models have oil drain plug so they do not need to be leaned in order to remove old oil. Go to local store and ask for suitable new lawn mower oil.

How to drain gas from lawn mower?

Gas can also become stale, especially during winter months when the lawn mower is not used. Old gas is a common reason why lawn mower will not start at the beginning of the new season after winter storage period. To prevent such problems you can start your mower every week or two during winter months and leave it working for five to ten minutes on a place. Stale gas is slowly producing sediments in carburetor and gas lines during the winter months. If you need to drain old gas from the gas container in order to replace it with the fresh one, you can use the same method as draining the oil – lean the lawn mower and drain gas in an appropriate container for disposal.

Replacing spare parts

Some parts of the lawn mower will become old or damaged over time and you will need to replace them. It is good to replace any rusted bolts or nuts. Buy new pieces of the same size and replace them since rusted bolts and nuts do not fully perform its function anymore. You can also replace dull blade as mentioned and described above. There are also many plastic parts that can be replaced if you lose them or they become damaged. You can buy spare gas cap or wheels if you need to replace them.

Winterize gas lawn mower

After the last mowing of a season, you should prepare your lawn mower for storage. It is recommended to clean your mower thoroughly. This means that you remove any excess residue of grass and dirt. Fast and very efficient way to do this is by using a compressor, that way you will easily remove dust and dirt. Water, soap and cleaning cloth can also be used, but you have to be careful not to expose motor directly to the water. When your mower is cleaned leave it in the sun so it can properly dry or use a clean cloth to remove any water by yourself. Fold mower’s handle if needed and put mower into the dry storage – moisture and humidity can harm any steel parts of lawn mower by rusting.


Taking care of your lawn mower is a very important process and by proper maintenance, you will prolong its lifespan. That way you will also save money in the long term since you will not be needed to buy spare parts so fast. Therefore it is recommended to consider our maintenance guide and keep your lawn mower in better condition.

Freelance writer with over 5 years experience in multiple niches. Specialist in personal care and men's grooming. Outdoor tools are something I'm pashioned about since I can remember. Other than that I do also like to travel and meet new people. "Research is creating new knowledge" - Neil Armstrong

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