Lawn Mower Maintenance: All You Need to Know
Are you tired of your lawn mower breaking down and your grass looking worse after mowing? It could be a sign that your lawn mower maintenance routine needs an update.
Whether you have a rotary or cylinder mower, follow our step-by-step guide below to keep both your lawn and machine in top condition.
1. Why Is Lawn Mower Maintenance Important?
To have a nice lawn, you need to look after your lawn mower.
An unkempt lawn mower is likely to have dull blades that tear the grass, instead of cutting it. This can cause your turf to look untidy and make it more susceptible to fungal infections and diseases. It will also slow the recovery process after mowing, meaning your grass will grow more slowly.
Regular care also helps your mower last longer. It reduces wear and tear, and you are less likely to deal with expensive repairs later on.
For best results, you should carry out a full lawn maintenance routine at least once a year. We also strongly recommend using gloves to protect your hands during this process.
2. Rotary Mowers
There are two different types of rotary mowers - electric and petrol. They both have different advantages and care needs.
- Petrol mowers are best for large gardens or areas with steep slopes. They can run for 1-2 hours per mow and have more power than electric models, making them ideal for tough terrain. To learn how to maintain a petrol mower, go to step 2.1.
- Electric mowers are quieter and work well for small, flat gardens. They come in two types: corded and cordless. Corded models are the most affordable but have a limited range due to the power cord. Cordless models offer more flexibility, running for 45-50 minutes per charge. To learn how to maintain an electric mower, go to step 2.4.
2.1 Remove and Inspect the Spark Plug
Start by removing the spark plug cap from your mower. This is done to make sure that your machine cannot start on its own unexpectedly, preventing potential hazards.
Next, closely inspect the spark plug. If it has some brown or grey deposits on the electrodes, this is completely normal. You can brush off any light dirt with a brush and reinstall it. However, if the spark plug has blisters on the insulator tip or melted electrodes, then the part is burned and must be replaced. Worn and eroded electrodes are another sign that the part needs replacing.
Spark plugs can also tell you a lot about the overall health of your machine. If you can see black soot on the electrodes and insulator tip, this indicates a carbon-fouled plug. This is often caused by a dirty air filter, so make sure to clean or replace it when changing the plug. Another thing to look out for are oily deposits on the electrodes and insulator tip. These could be a sign of the oil leaking into the cylinder. If this happens, ask a professional to help you find the source of the leak and only replace the spark plug once the issue has been fixed. Alternatively, if the electrodes are flattened or broken, then your spark plug may not be the right size for your engine. Check your owner’s manual to make sure that you order a correct replacement.
Sometimes, even a spark plug that looks fine still needs replacing. This happens because the part wears out over time. There is no set timeframe when this will happen as it depends on several factors, including how well the mower is maintained, how often you use it, and how long each mowing session lasts. Usually, if your engine starts running roughly, it is a sign to investigate if you need to get a new one.
For step-by-step instructions on fitting or replacing the spark plug, check your owner’s manual.
2.2. Check the Oil & Fuel Level.
To check the oil level, make sure to pull out the dipstick from the oil reservoir, wipe it clean, and then put it into the reservoir again. Once you take it back out, it should now show you whether the oil reaches the designated mark on the dipstick. If not, make sure to top it up following the instructions given in your machine’s manual. This is important as not having enough oil can result in your mower overheating, which could permanently damage it.
If you do have to buy a new oil, make sure to check the machine’s manual to get the right type. While it is a common belief that a car oil can be used, this is false as it can damage your machine.
This is also a great time to check the fuel level and top it up if necessary. Since September 2021, the petrol you get at UK petrol stations has changed to E10. It has 10% ethanol, instead of 5% that the old petrol, E5, did. This change was to help lower the amount of CO2 that cars and machines release. Unfortunately, E10 petrol doesn't last as long as the old E5. This is because ethanol soaks up moisture from the air. This water can then cause rust inside your petrol tank, your machine might also not run properly on petrol that's been watered down.
To stop this from happening, you should always use a petrol stabiliser. This is especially important when you are not planning to use your lawnmower for a long time, like over the winter. This will ensure that your machine stays in the best condition.
2.3 Check the Air Filter
The air filter helps the engine get the right amount of air that it needs to run properly. Over time, it can get clogged with grass clippings and dust. To keep your mower in good shape, clean the filter regularly with soap and water.
Alternatively, if the filter is too dirty, it’s best to replace it since new filters usually only cost around £10.
Check your owner's manual to find out which type of air filter your mower needs.
2.4 Clean the Underside of a Mower
Cleaning the underside of your mower, also known as the mower’s deck, is a key part of lawn mower maintenance as it improves airflow and prevents your mower from rusting.
If you have a petrol mower, then you have already taken the necessary safety precautions for this step. For electric mower users, make sure that your machine is not plugged in if you have a corded model or that the battery has been removed if you have a cordless one. This ensures that the machine does not start unexpectedly.
Start by tipping your mower to the side. If you have a petrol mower, make sure to tip it carburetor side up to prevent the oil and fuel from flooding your machine, then use a brush to remove any remaining grass clippings. Failing to do so can cause your machine to overheat and potentially break down. Next, make sure to wipe the area with a damp cloth to prevent grass buildup in the future and stop the machine from rusting.
This is also a great time to check the condition of your mower’s belt if you have a petrol-powered machine. The belt should be partially exposed when looking at the underside of the mower, giving you a chance to look for any cracks, cuts, or tears. If you notice any of these, then it is time to replace it. Refer to your machine’s guide to find out how to do this.
Finally, check that the wheels are working properly and tighten any bolts or screws as necessary.
2.5 Sharpen the blades
To sharpen your blade, you must first take it off. Make sure to check your owner’s manual for specific instructions on how to do this, but generally, you can use a wrench to loosen the blade. You can also use a permanent marker to mark the underside of the blade to make sure that you re-install it correctly, but this step is optional.
Once this is done, remove any dirt and leftover grass clippings. This can be done with a brush, dish soap, and a putty knife, depending on how dirty your blade is. A brush is enough to tackle light dirt, while for heavier dirt, it is best to soak the blade in a mixture of dish soap and water overnight, then use a putty knife to remove any leftover debris.
It is also worth inspecting the blade itself at this stage- if it is badly damaged, then it may be best to replace it instead following the instructions given in the manual for your machine.
If it is still in good condition, it is time to sharpen it. Clamp the blade within a vice so that it is stable, then use a file or a grinder. Since your blade is already angled, it is important to keep that same angle as you sharpen it. Make sure to move your file or grinder from the inside of the sharp edge to the outside. You should be aiming for a butter-knife level of sharpness for best results.
Once you have done the first side, make sure to flip the blade over and do the exact same thing on the second side. Next, use a blade balancer or balance the blade over its centre to see if it's evenly balanced. If not, then sharpen the side that tips it over until it does not anymore.
Lastly, reinstall your blade referring to your mower’s manual for further instructions on how to do this.
2.6 Wipe the Mower’s Exterior with a Damp Cloth
To keep your mower looking its best and prevent rust, finish your lawn mower maintenance routine by wiping it down. Use a damp cloth to clean the outside, especially the wheels and the area around the engine. This helps remove dried mud, dirt, and grass clippings. This method allows for better control than washing your mower directly using a garden hose, which could result in water damage. If there is still some dirt left afterwards, you can use mild dish soap or car wash soap to get rid of it.
We recommend doing this after every use to keep your mower in top shape.
3. Cylinder Mowers
There are three different types of cylinder mowers – hand push (manual), electric and petrol.
A hand push mower refers to a lawn mower that is pushed along the ground to cut grass and does not require any electricity or petrol. Because of this, it is considered an eco-friendly option. It also needs minimal maintenance.
An electric cylinder mower does have an engine that is powered by electricity which helps the blades to rotate. Some electric mowers are also self-propelled, which is when the motor also drives the wheels or rollers. This makes it easier to push the machine. This type of mower requires more maintenance than a hand push one, but less maintenance than a petrol model.
A petrol cylinder mower works the same way as an electric one and can be either a push or self-propelled. These mowers need additional maintenance that the hand push and electric mowers do not, including checking the spark plugs, oil, petrol levels, and changing the air filters.
If you have a petrol cylinder mower, read through steps 2.1 - 2.3 and then follow the rest of the steps below for a full maintenance routine.
3.1 Readjust the Cylinder
To check if your cylinder needs adjusting, do a simple paper test. Place a piece of printer paper between the bedknife and cylinder blade. Slowly turn the cylinder with your other hand, moving the paper up as each blade cuts. Test the left, middle, and right sides to see if it cuts cleanly. If it does, your mower is set up correctly and no further action is needed. On the other hand, if the cuts are not even, the cylinder blade will need readjusting to make sure that it is able to give your grass a clean cut instead of tearing it. Most mowers have screws or bolts on the sides for this but make sure to check your owner’s manual first before touching these. After adjusting, repeat the paper test to make sure the blades cut evenly. If not, readjust it again.
For best results, we recommend you perform the paper test before each mow.
If you have a petrol cylinder mower, adjusting the cylinder blade may have affected the chains’ tension. These are usually located on both sides of the blade. First, remove any covers to access them. Then, press lightly on each chain with your thumb. The correct tension depends on your mower’s model, but generally, you should be able to move them in and out by at least 5 millimetres without too much effort. If the chain is too loose or too tight, you need to readjust it. Make sure to check your owner’s manual to learn how to do this.
Lastly, before putting the covers back on, make sure that the chains are well-lubricated.
3.2 Back Lapping
Back lapping is a process used to sharpen the cylinder blades and bedknife of your mower without having to take them off. It is done using a water-soluble grinding paste, called back lapping paste. Depending on the condition of your lawn and how often you mow, this process can be done before every use or every few weeks.
To start turn your mower backwards to access the cylinder blades and bedknife easily, then use a file to sharpen the edge of the bedknife. Once this is done, use a back lapping machine or a cordless drill with a socket attachment to spin the cylinder in reverse. While it spins, spray it with water to spread the grinding paste evenly. Then, use a paintbrush to apply the paste to the blades, covering them fully. Let the cylinder spin for up to 10 minutes, making sure your hands are kept away from the blades during this time. Once this is done, wash off any paste with a hose.
After your mower is dry, spray all the moving parts, including the cylinder and bedknife, with WD-40. This will stop them from rusting and keep your mower working well for longer.
If your blades aren't sharper after doing this, they might need to be re-sharpened. Make sure to check your mower's handbook for advice on this.
3.3 Clean your mower
To finish your lawn mower maintenance, clean your mower properly. Wipe off any grass clippings and dirt with a damp cloth. Then, use a leaf blower to dry it. This helps stop water from sitting on it for too long, reducing the risk of rust or water damage.
We recommend doing this after every use to keep your mower in top shape.
Keeping your lawn mower in good condition is key to having a beautiful, lush lawn. If not taken care of regularly, your machine’s blades can go dull, tearing the grass instead of cutting it. This can make your lawn look yellow and untidy. The mower is also more likely to break down, resulting in costly repairs.
This is why knowing how to take care of your mower is so important. By following the right steps for your model, you can avoid these problems and keep your mower working well for many years.
