How to Service a Lawn Mower

How to Service a Lawn Mower

A lawn mower is an essential piece of equipment when caring for your lawn.  Like all machinery, it may need service and maintenance in order to keep it running and in tip top shape. If you’re wondering how to service a lawn mower to make your machine last, I’ve got you covered.

While it may seem obvious that your lawn mower will need maintenance, the lawn mower is one of the least maintained pieces of machinery in most people’s homes and is one that takes most of the beating during peak seasons.

In this in-depth article I’ll explain how to service a lawn mower, covering just about every aspect of routine maintenance you need to know about.

So without delay, here are a few tips to ensure your lawn mower is in working shape when you need it:

Get to Know Your Lawn Mower

Knowing your lawn mower inside and out is a great way to ensure that you not only know how your lawn mower works, but that you know when your lawn mower isn’t working correctly. 

I recommend that you read your lawn mowers owner’s manual before using it and before storing it for long periods of time.  It also might be a good idea to brush up every couple of years by leafing through it at the beginning of a new season.

If you’re like me, you tend to forget things, especially things that aren’t on the top of your priority list. Reading your lawn mowers owner’s manual will ensure that you are able to take the best care of your lawn mower possible.

It’s a great first step to protect your investment.

Store Your Lawn Mower Properly

Taking good care of your lawn mower doesn’t stop when the mowing season stops.  It is important to care for your lawn mower all year round, especially when it is going to sit for a long period of time, or when you first pull it out after it has been sitting.

When storing your lawn mower for long periods of time, be sure to drain the gasoline from the mower.  Old gasoline in your lawn mower could cause it to not start when peak mowing season comes around.

It’s more expensive, but you can also buy gas that is ethanol-free. This type of gasoline you can leave in your machine year-round and you don’t have to worry about it going bad. For me, it’s worth the extra money (at least early in the spring and late in the fall).

If you forget to drain the gas our of your lawn mower, here are some tips for getting your mower started again when peak season comes around:

How to Drain Bad Gas From Your Mower

  1. Clean out your lawn mower’s gas tank.  You can refer to your lawn mowers owner’s manual for instructions on how to get inside of your mowers fuel tank.
  2. Remove any remaining gas from your gas tank.  Once the gasoline build up is gone, siphon all of the old gas into a container before adding new gas.
  3. Ensure that the spark plug is installed properly.  Often, the spark plug in your lawn mower can come loose.  After draining the old gas out of your lawn mower, be sure the spark plug wire is all the way in.  This will give you the best chance at restarting your lawn mower.
  4. Add the new gas and start slow.  After adding the new gasoline, start slow when starting your lawn mower.  When the smell of gas becomes strong, stop.  A strong smell of gas means that you have flooded your carburetor.

Check your Lawn Mower’s Oil

Oil in a lawn mower is essential for proper functioning, and if you want to learn how to service a lawn mower, learning to change your mower’s oil is the first step. 

You should change the oil in your lawn mower once every other mowing season minimum (I recommend doing it once a year because it’s easy and inexpensive to do).

How to Change the Oil in Your Lawn Mower

  1. Drain all of the gasoline from your lawn mower (optional – I usually don’t do this, but some people recommend it)
  2. Disconnect the spark plug wire (good safety practice)
  3. Check to see if your lawn mower has an oil drain plug.  Some lawn mowers, especially larger ones and riding mowers will have an oil drain plug.  Smaller walk-behind lawn mowers generally do not have an oil drain plug.
    1. If your lawn mower has an oil drain plug, pull the plug and drain the oil into a pan or container like you would with a car.
    2. If your lawn mower does not have an oil drain plug, tip your lawn mower on its side, being sure to keep the carburetor on the raised side, and drain all of the oil out of the mower. In a push mower this is usually done right through the hole where the dipstick is where you add oil. They’re almost always built with the carb on the other side.
  4. After draining all of the old oil out, tilt your lawn mower upright and add the new, clean oil.

Clean the Mower’s Undercarriage

One common lawn mower maintenance item that is often overlooked is cleaning out the undercarriage. 

Grass, especially if you mowed wet grass, can get caked to the underside of your lawn mower and clog up your lawn mower’s discharge chute. 

It can also rust your mower deck and your blades.

Lawn Mower Service Regimen

Cleaning the undercarriage of your lawn mower is easier if you have a smaller, push mower.  If you have a larger, riding mower, I recommend seeking professional help.

For smaller, push mowers, unplug the spark plug wire and tip your mower on its side.  Using a wire brush, scrape the grass clippings and dirt off the undercarriage.  Be careful not to scratch the painted finish much because that’ll result in easy spots for rust to develop.

Once the majority of the buildup has been scraped off, use a hose to spray the remaining debris off the undercarriage of your lawn mower and let it dry.

Your Lawn Mower Needs Clean Air

Your lawn mower’s air filter picks up a lot of dirt and dust, especially if you live in a dry, dusty climate or your lawn has bare spots. 

It is important to clean the air filter in your lawn mower, just like it is important to clean the air filter in your car.  A dirty air filter will put more stress on your lawn mower and waste gas.

I clean mine by removing it, shaking it gently and then blowing on each side to remove any larger dust particles before each use.

I also replace my air filter annually. It’s easy to do and inexpensive and when you’re first learning how to service a lawn mower, this is one maintenance step that is easy to master.

I recommend that you replace the air filter in your mower once a year to ensure optimal performance. It’s usually wise to buy a couple when you go to the store so if you notice it’s dirty during lawn maintenance season, you have one handy to save you a trip to the store.

Spark Plug Replacement: A Satisfying Part of Servicing a Lawn Mower

Another thing that you should change annually is your spark plug.  Spark plugs ensure that your lawn mower will start up easily.

Here are some tips to change your spark plug:

Regular Lawn Mower Service - Spark Plug Replacement

How to Change a Lawn Mower Spark Plug

  1. Unplug the spark plug wire.
  2. Remove the old spark plug with a spark plug wrench or socket. Most people don’t have a socket long enough for this task in their set, so you might need to buy a new one. Your mower’s manual will tell you what size to buy.
  3. Place the new plug into the socket, ensuring that you do not tighten it down too much.  Overtightening your spark plug could prevent your lawn mower from starting. You want it just beyond finger tight.

Sharpen Your Lawn Mower Blades

Let’s face it … other than that guy or gal across the street nobody has a perfect lawn (every neighborhood has that neighbor).

Because nobody’s yards are perfect and most are filled with rocks, roots, sticks, and other hard, blunt objects, your mower’s blades can take a beating.  They endure a lot of stress, especially during peak mowing season. 

It is important to keep your mower’s blades sharp.

Dull lawn mower blades rip and tear the grass instead of cutting it, causing damage to your mower and to your lawn. Learning to sharpen your lawn mower blades will make a huge difference in your lawn’s performance.

Plus it’s super satisfying to learn and do. It was one of my favorite steps when first learning how to service a lawn mower.

If you are not handy, I recommend hiring a professional to help sharpen your lawn mower blades. 

Some people use a metal file to sharpen their lawn mower’s blades and others use an angle grinder. Doing this improperly can be dangerous. You could damage your mower, so gauge for yourself whether or not this is for you.

I found it pretty easy to master and I find it relaxing and fun. But I also have a blog about lawn care, so I may not be speaking for the masses. 🙂

How to Service a Lawn Mower: Explained

Regular maintenance routines on your lawn mower vary. What you need to do to regularly service your mower will depend upon:

  • the size of your mower,
  • how often you use it, and
  • the size and condition of your property.

Here is a summary of the basic service you should perform on your lawn mower:

Recommended Lawn Mower Service Items

  1. Understand how your lawn mower works and know how to tell when it is broken.  By reading your owner’s manual you can know when your lawn mower is working properly.  You can also know how it is supposed to feel and sound, so when it is not working properly, you can pinpoint the problem. Most manuals have a page dedicated to common problems and how to fix them.
  2. Don’t just abandon your mower after the final use of the year and let it sit during non-mowing seasons.  Your lawn mower needs attention even when you are not mowing.  Before you leave your lawnmower in the back of your garage for the winter be sure to drain all of the gasoline. Disposal is easy – just dump it into your car’s gas tank.  This will save you some headaches when it is time to pull the mower out again and use it.
    1. If you forget to drain your lawn mower of gasoline, don’t fret, use the tips in this article to get your lawn mower back up and running after a winter with old gasoline.
    2. If you use TruFuel or another ethanol-free gas, you don’t need to drain your tank. You can also treat your gas to winterize it, but many people do this incorrectly, so I don’t recommend it.
  3. Change the oil in your lawn mower annually.  Old oil can cause your mower to not start.  It is important to change your oil at least once a year to ensure that there are no particles in your oil and that your lawn mower runs perfectly. If your mower is smoking, or if you check the dipstick and see dark black oil, change it.
  4. Clean the underside of your lawn mower.  One neglected part of everybody’s lawnmower is the underside.  Wet grass clippings can build up on the underside of your lawn mower, causing reduced performance and clogging of the discard chute. It can also rust your mower deck.  Using a metal brush scrape the undercarriage of your lawn mower to clear up any build up.
  5. Clean your lawn mower’s air filter regularly and replace it annually.  This is especially important if you live in a dry area or have bare spots in your lawn.  Dust can build up on your air filter and cause the lawn mower to not start.
  6. Replace the spark plug.  You should replace your spark plug every other year (I recommend doing it every year before your first mow).  Follow the above steps to learn how to replace your spark plug.  Be sure to not tighten the new spark plug down too much.  Tightening it down too much can actually cause damage and cause the lawn mower not to start.
  7. Sharpen the blades.  Like most blades, your lawn mower blades can get dull from hidden debris and rocks.  I recommend that most people go to a professional to sharpen lawn mower blades, as this task can be dangerous.

The Satisfaction of Caring For Your Lawn Mower

Learn How to Service a Lawn Mower

Servicing your lawn mower is important if you want to keep it running well.  I’m a huge advocate for DIY, but if it seems overwhelming hire a professional to service your machine annually.

Protect your investment and take care of your lawn mower following these simple service tips. Your mower will remain in tip-top shape for years.


Sarah Jameson’s blog, Lawn Chick, is read by over 2 million homeowners each year and she is regularly cited as an expert source of lawn care knowledge by major publications. Her goal is to meet you where you are, and help you achieve a yard you’ll be proud of. Ready to take the next step toward improving your lawn? Grab her free lawn care cheat-sheet: What to Do When - Take the Guesswork Out of Lawn Care, or upgrade your garage by browsing her favorite DIY lawn care products.

Leave a Reply

Your email address will not be published. Required fields are marked *