How to Service Your Lawn Mower

Cleaning your lawn mower

One of the most crucial aspects of lawn mower maintenance is cleaning.  

Leaving your mower dirty can affect its performance, cause metal parts to rust, and promote the growth of mould and fungus which can easily be spread across your lawn causing unsightly damage. 

Cleaning your lawn mower can help prevent these issues and extend its lifespan, giving you years of trouble-free mowing.  

Here are the key steps to follow: 

1. Disconnect the spark plug – Before you start cleaning, disconnect the spark plug to make sure the engine can’t accidentally start. 
2. Remove the blades – Remove the blades by unscrewing the bolts that hold them in place. 
3. Clean the blades – Use a brush to remove any debris or grass clippings that may be stuck on the blades. If the blades are rusty, blunt or damaged, consider replacing them. 
4. Clean the deck – Use a scraper or a stiff brush to remove any dirt, grass, or debris from the deck. Avoid using a wire brush which can be too rough and damage the paint. 
5. Clean the catcher – Unhook the catcher or clippings bag from the mower and brush out any dried lawn clippings. Use a garden hose to wash it out if it’s dirty. 
6. Wash the mower – Use a garden hose to wash the mower. Avoid using a pressure washer as it can damage the engine or electrical components. Use a mild detergent or degreaser to clean away stubborn grease stains or dirt. 
7. Dry the mower – Once you have finished washing, dry the mower with a towel or leave it to air dry. 

Cleaning the air filter

The air filter is an essential component of your lawn mower’s engine as it prevents dust and debris from entering the engine.  

A dirty air filter can interfere with the mower’s performance and cause the engine to overheat. It is advisable that you check the air filter every season. The key steps to follow when cleaning the air filter are: 

1. Find the air filter – The air filter is usually located near the engine and covered by a plastic or metal cover. 
2. Remove the cover – Unscrew the bolts or clips holding the cover in place and remove the cover. 
3. Remove the filter – Remove the air filter from the housing and inspect it for damage or wear. 
4. Clean the filter – Tap the filter and use compressed air or a soft brush to remove any dust or debris. Avoid using water or cleaning agents which can damage the filter. 
5. Reassemble – Once you have finished cleaning the filter, or decided it needs replacing, reassemble the cover and bolts or clips. 

Changing the spark plug

The spark plug is responsible for igniting the fuel mixture in the engine’s combustion chamber. 

A damaged or worn spark plug can cause your lawn mower to run poorly or not start at all. We recommend spark plugs be replaced every 12 months or sooner if your mower gets a lot of use. 

Here are the key steps to follow when changing the spark plug: 

1. Disconnect the spark plug – Before you start, disconnect the spark plug to make sure the mower doesn’t start accidentally. 
2. Remove the old spark plug – Using a spark plug wrench, undo and remove the old spark plug from the engine. 
3. Inspect the new spark plug – Check the gap between the electrodes of the new spark plug using a spark plug gap tool. 
4. Install the new spark plug – Lubricate the spark plug with a small amount of oil, then install it into the engine and use the spark plug wrench to tighten it. 
5. Reconnect the spark plug – Reconnect the spark plug wire to the new spark plug. 

Changing the oil

Regularly changing the oil in your lawn mower can help it run more smoothly and last longer.  

Most manufacturers recommend changing the oil after every 50 hours of use or at least once a year.  

This applies only to four-stroke mowers which have a separate reservoir for oil. Mowers with two-stroke engines require a mixture of petrol and oil to be added to the fuel tank. 

There’s more information about the differences between four-stroke and two-stroke lawn mowers here. 

Key steps to follow when changing the oil are: 

1. Disconnect the spark plug and turn the mower onto its side with the air filter facing up.  
2. Remove the oil cap and tilt the mower towards the oil drain plug to drain the old oil into a container.  
3. Once the oil has drained out, replace the drain plug and refill the engine with the recommended amount of new oil. You’ll notice it’s a brighter, clearer colour than the old oil. 

Be sure to check the owner’s manual for the exact type and amount of oil needed for your lawn mower. 

Sharpening the blade

A dull blade can damage your lawn and make your mower work harder than it needs to, leading to decreased performance and a shorter lifespan.

Sharpening the blade is an essential part of lawn mower maintenance and should be done at least once a year, more often if you have a large lawn or frequently encounter rocks or other debris.

Key steps to follow when sharpening the blade are: 

1. Disconnect the spark plug and turn the mower on its side.  
2. Use a socket wrench to remove the blade and clamp it in a vice.  
3. Use a metal file or grinder to sharpen the edge of the blade.  
4. Be sure to maintain the angle and balance of the blade while sharpening, and ensure it is properly balanced before reattaching it to the mower. 
5. Always wear safety gloves and eye protection when working with mower blades. 

Checking the fuel system

Over time, dirt and debris can accumulate in the fuel system, leading to blockages and poor performance.  

To prevent this, it’s important to regularly check the fuel system and clean or replace any parts as needed.  

Key steps to follow when checking the fuel system are: 

1. Disconnect the spark plug. 
2. Remove the fuel cap to release any pressure in the system.  
3. Remove the fuel filter and check for dirt or debris. If the filter is dirty, clean or replace it, as needed.  
4. Inspect the fuel lines and connections for any cracks or leaks.  
5. Check the carburettor for dirt or debris and clean or replace it, if necessary.

Inspecting the belts and cables

On larger mowers such as ride-ons, the belts and cables in your lawn mower can become worn or damaged over time. This will lead to reduced performance or even complete failure.  

To prevent this, it’s important to regularly inspect the belts and cables and replace any that are worn or damaged.  

Key steps to follow when inspecting belts and cables are: 

1. Disconnect the spark plug. 
2. Remove the mower deck.  
3. Check the belts for signs of wear, such as cracks or fraying. 
4. If the belts are worn, replace them with new ones of the same size and type.  
5. Inspect cables for signs of wear or damage, such as fraying or corrosion.  
6. If the cables are worn, replace them with new ones of the same length and type.

Apply lubricant

Spray a lubricant such as WD40 onto moving parts, including the wheels, throttle cable and height adjustment lever, using a rag to wipe off any excess. 

Once you’ve finished servicing your mower, store it in a safe, dry place when not in use. 

This article contains general information that might not apply to all mowers. 

If you need information specific to your particular model, refer to the owner’s manual or go online to check the manufacturer’s instructions and recommendations. 

Or if you’re in the market for a new mower, take a look at our Lawn Mower Buyers Guide. 

Conclusion  

Regular lawn mower maintenance is essential for keeping your mower running smoothly and efficiently for years to come.  

By following these simple steps for cleaning, oiling, sharpening, and inspecting your lawn mower, you can ensure it’s always in top shape and ready to tackle any job.  

Remember to always wear proper safety gear, such as gloves and eye protection, when working on your lawn mower.