Fix lawn mower blade. How to Sharpen Your Lawn Mower Blade for a Cleaner Cut

Lawn Mower Blade Spins Freely: Maintaining a Blade

A lawn mower is a handy homestead tool that utilizes revolving blades to cut grass. As such, the blades of your mower must be sharp, in good shape, and secured in place to cut grass effectively, neatly, and evenly. Normally, lawn mower blades are connected directly or indirectly via belts or other mechanisms to the engine. If you notice that your lawn mower blade is spinning freely (without cutting grass), then this is an indicator that there is a problem.

Lawnmower blades normally should not spin freely, so you need to look into what is causing your mower blade to spin. The causes can vary greatly, depending on whether you have a push or ride-on mower.

If your lawn mower has recently started producing a rattling sound and its blades are spinning freely, it is important to identify the root problem and address it before it worsens. In this post, you will find potential reasons why your lawn mower blade is spinning freely, along with feasible solutions.

Why is your lawn mower blade spinning freely?

If you own a lawn mower, it is imperative to gain insight into how the components of your mower operate. Understanding how each component works will make it easier for you to find problems and fix them whenever they show up.

Lawn mower blades are an essential component of any lawn mower. To cut grass evenly and neatly, they must be securely attached so that they don’t move freely. However, how tight your lawn mower blade should be will depend on the type of mower you have.

On the other hand, a loose mower blade is a recipe for an accident. Besides causing your mowing machine to operate inefficiently, a mower blade that’s spinning freely can easily come off during mowing, posing a serious safety hazard. Here are possible reasons for a mower blade to spin freely, depending on the type of mower you have.

Push mowers

Push mowers usually have an internal combustion engine that relies on compression to transfer energy. As such, the principle of compression is critical to the functioning of your lawnmower. If the blade of your push lawn mower is spinning freely, low engine compression is most likely to be the culprit. This is because their blades are usually connected to the engine by an axle.

Lack of compression often results from leaks in one or more of your mower cylinders. While there are many causes of compression loss, the most common is normal engine wear and tear. However, you may want to check just to ensure that the engine problems are not a result of another issue.

Riding mowers (Tractors)

Unlike push lawn mowers whose blades are directly connected to the engine by an axle, riding mower blades are normally powered by a belt connected to the engine. As such, if the blades spin freely, a faulty or missing belt is likely to be the cause.

Over time, the belt that brings the engine power to your mower blades can break or wear out to a point where it is loose and can’t turn the blades. If you notice your lawn mower blade is turning freely, check if the belt is in good condition.

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Fixing loose blades in push lawn mowers

Lawn mower blades are meant to be secured properly and should never spin freely, except ONLY when the mower has a clutch. If your push lawn mower blade is spinning freely, follow these steps to fix it:

  • Empty the gas tank. You can use a hand siphon.
  • Turn your mower over.
  • Inspect your lawn for things that may cause the blade to spin freely. Possible causes include compression loss, the blade not being centered, the bolt not being tight enough, and deformations.
  • Place a wedge between the blade and deck to stop the blades from spinning.
  • Fix the problem. If you have compression loss, the best solution is to replace the leaking component — piston, piston ring, valve, or head gasket. Most of the other issues require tightening.
  • Turn the mower to its wheels.

Fixing loose blades in riding lawn mowers

When it comes to fixing loose riding mower blades, the most important thing is to identify whatever causes your mower blade to spin freely. Follow these steps to fix your riding lawn mower.

  • Park your mower on flat ground and away from obstacles
  • Raise the deck to the highest position and turn it off.
  • Inspect your lawn mower. A torn or worn-out belt is likely to be the problem. If the belt that drives the lawn mower blade is in good shape, check if the bolts are tight.
  • If your lawn mower belt is too old, missing, or worn out, replace it with a new one. You may also want to tighten the bolts.

Once you have fixed your lawn mower, keep it in a safe place. Lawn mower components can be hurt by inclement weather, so it is best to keep your lawn mower in the garage or garden shed.


It can be annoying to have your lawnmower blade spinning freely. No matter the cause, you should consider fixing it immediately. Hopefully, this post will help you fix your loose lawn mower blade.

How to Sharpen Your Lawn Mower Blade for a Cleaner Cut

Follow this easy guide to sharpening the business end of your mower and your grass will look tidier and stay healthier all season long.

Lawn Mower Blade balancer

Viveka Neveln is the Garden Editor at BHG and a degreed horticulturist with broad gardening expertise earned over 3 decades of practice and study. She has more than 20 years of experience writing and editing for both print and digital media.

When your lawn mower isn’t making the cut anymore, usually it’s because the blade has lost its sharp edge from use. Removing the blade and sharpening it yourself can seem intimidating if you’ve never done it before. But it’s actually a simple process, and you’ll only need two tools to do it.

Once you know how to sharpen your lawn mower blade, it’ll take you a fraction of the time it takes to mow your lawn. So, just follow this step-by-step guide to give your grass a crisp, clean cut again. Or, if you don’t want to worry about sharpening the blade, you can just remove it and bring it to a lawn mower repair service near you to take care of it.

Test Garden Tip: When grass blades have torn, ragged ends that turn brown after a mowing, chances are it’s time to give the blade some attention. Most experts recommend sharpening power mower blades once or twice a season, depending on how often you use your mower.

Step 1: Remove Blade from Mower

Disconnect the spark plug on a gas mower or unplug an electric mower (to ensure the machine won’t accidentally start while you’re working on it). Next, gently lay the mower on its side and use a wrench (27, The Home Depot) to remove the nut that attaches the blade to the motor. Then, remove the blade from the mower. To make sure you replace it the right way in the machine, mark the bottom of the blade with spray paint so you know that it should face the ground when you’re done.

Step 2: File Blade

Clean any dirt or grass clippings off the blade with a dry cloth. Stabilize the blade in a vise and use a medium file (10, The Home Depot) to smooth out imperfections along the blade edge (at the ends of mulching blades). Follow the existing angle of the blade, holding your file or sharpening tool at about a 45-degree angle. Move the file in one direction, gliding out toward the edge, much like you would sharpen a kitchen knife. However, your goal is to make the edge about as sharp as a butter knife rather than your favorite chef knife.

Step 3: Check for Balance

After you hone the cutting edge on both halves of the blade, check to see if the blade is balanced. An easy way to do this is to pound a long nail into a wall in your garage and rest the blade’s center on the nail. If the blade isn’t balanced, file a little more metal from the heavier side until it balances.

Step 4: Reassemble Mower

When the blade is correctly balanced, put the mower blade back onto the machine using a wrench. Be sure to tighten the nut securely back into place. And don’t forget to reattach the spark plugs.

Lawn Mower Leaving Uncut Grass – The complete fix with pics

It’s a common source of frustration, and ARGH!! But more than likely, the solution is a simple one, and you can fix it right now.

So why is my lawnmower leaving uncut grass? The most common cause of uncut grass is a dull blade, but it’s not the only possible reason:

This problem has many possible causes, but a dull blade is a usual suspect. Check your engine performance; if you feel the engine doesn’t sound right or it’s sluggish, go ahead and solve engine-related issues first.

Very often, uncut grass is simply caused by a dull blade. If you need help inspecting and safely sharpening your blade, check out “How to sharpen mower blade video”.

Check For Blade Damage

A defective blade will cause all kinds of problems in the grass-cutting and collection department. Examine your blade checking for loose bolts, and damaged, misaligned, bent, or broken blade tips.

Mower blades have it tough, and hitting stones, sprinklers, stumps, and dog toys is all part of the job. Mower blades turn about 50 times a second – that’s 200 mph at the tip.

So when you hit something, it’s going to damage even hardened steel. Bending and gouging chunks from the metal blade will cause uneven cutting and a horrible vibration.

A blade may look OK, but they do wear. If it’s more than four seasons old, it’s probably worn out. The leading edge cuts the grass and is easy to see when it’s worn. The trailing edge stuffs the bag, and as that edge wears, it becomes much less efficient. The solution – replace the blade.

Never attempt to repair or bend a blade; the metal has been specially treated, and interfering with this can cause them to shatter.

When replacing the blade, go ahead and get a new bolt and washer. They’re mower-specific and also specially treated, so a bolt from the local hardware store won’t be up to the job.

A torque wrench should be used to tighten the bolt to the correct specification. A quick check of your mower manual or on the dealer site will give the spec.

Blade Orientation

It’s possible to fit a blade backways, so if you fit a blade recently, just check that the orientation is correct. Hey, it could happen a Bishop, don’t worry about it!

Imagine looking down at the blade from above – the leading edge of the blade will turn clockwise.

Bent – A bent blade is dangerous, and it will cause lawn scalping and vibration and, if ignored, will damage the mower engine.

Replace – A new blade will solve many problems; when changing the blade, replace the bolt and washer too.

If you need video help replacing the blade, check out the “Replacing blade video” and if you need mower blades, check out the Amazon link below.

Dull Blade

Is your blade sharp? A dull blade is the number one reason for leaving uncut grass. The blunt blade will damage your lawn in no time at all; it tears the grass and leaves a jagged edge which turns the grass tips yellow.

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The recommended way to repair the yellow grass damage – regularly cut with a sharp lawnmower blade. I tell my customers to sharpen at least once per season, and more depending on how often you cut and terrain type. A sharp blade is the secret to a healthy, beautiful green lawn.

Check out “Blade maintenance tools” here; they make the sharpening process a ton easier. And if you need video help sharpening the blade on or off the mower, check out the “Blade sharpening video”.

Sharpen – Your blade needs a sharpening once per season, at least. If you file your blade regularly, it won’t take much effort to keep sharp.

What Blade Type?

You may have a blade that doesn’t suit your climate or your needs. So what’s in a blade? Quite a lot of clever engineering, actually. A blade looks pretty unimpressive, but change it out for a different type or a new one, and you’ll be surprised at the difference in cut and finish.

There are two main blade types, the lift blade, and the mulching blade; each has its own strengths. How you intend to handle your clippings and your climate will likely dictate which blade suits you.

Lift Blade

The Lift blade, also known as the 2 in 1 (collecting or discharging), vacuums the grass upright, before cutting and moving it to the bag. These lift blades are designed for collecting grass and come in low, medium, and high lift.

Lift means sucking power, and a higher lift blade will require a more powerful engine. The lift is created by curving upwards of the trailing edge of the blade; the steeper curve, the more powerful the lift. These blades love to bag grass, wet or dry.

Lift blade – Also known as a 2-in-1, it loves to bag grass, wet or dry.

Mulching Blade

A true Mulching blade is designed to finely chop and disperse grass clippings, not collect them, a proper mulching mower won’t have a grass bag.

Many of the latest mowers are fitted with a hybrid mulching blade, also known as a 3-in-1 (collecting, discharging, or mulching). It’s sort of half lift blade, half mulching blade – Jack of all trades if you like.

These blades are not designed specifically to collect and are really best suited to very regular dry weather cutting; if the grass is tall, a 3 in 1 mulching blade may struggle to bag efficiently.

Mulching – 3 in 1 blade is good but has limited success in more challenging conditions.

Check Engine Power

Check if the throttle is set correctly; it should be set to fast/run when cutting. Does your throttle cable need adjustment? Is the engine running as it should? If the engine power is reduced, the mower will not cut well, especially when it hits a patch of heavy grass.

Lawnmowers are generally very reliable; give them a tune-up and blade sharpening at the start of every season, regardless of how it’s running. The oil should be changed every 50 hours, and clean the air filter every 25 hours, and more often in dusty dry conditions.

How To SHARPEN And BALANCE A Lawn Mower Blade (The Correct Way)

Check throttle lever – If your engine seems to be a bit sluggish, first check that the throttle is set to full. The lever may be reading full throttle, but the cable may not be moving at the carburetor end.

Second, check the air filter is clean, try running the engine without the filter, and see if it makes any difference.

Gas – Old fuel is the number one cause of poor engine performance. Fuel older than a month goes stale and will gum up the inside of the carburetor.

This blocks the fuel feed ports and causes fuel starvation. This results in a sluggish engine and a poorly cut lawn.

Try using a fuel stabilizer, it will keep the gas fresh for up to two years, but more importantly, it will prevent gumming up of the carburetor. Check out the video showing how to mix and add gas stabilizer. The page includes a link to the gas stabilizer I use.

If you suspect bad gas is causing sluggish engine output, try draining the fuel tank, and carburetor bowl, and filling them with fresh gas. This will very often fix the issue, and if it doesn’t, a full carburetor cleanout will.

Clutch Slip

If you’re using a tractor mower, you may have a clutch system fitted. The clutch or PTO (power take-off) transfers the engine power to the blades. When the clutch starts to fail, it slips, which means the blades are not turning with the same power or speed as normal. It will be especially noticeable in taller, heavier grass.

Some walk behind lawn mowers (Honda) use a very similar clutch set up, so if you have a separate control to engage the blade, then it’s likely you have some form of the clutch system, but note these clutch systems are cable operated and the tension on the cable may simply need to be adjusted.

If you don’t have a clutch fitted, but you do have a separate lever to control the blades, then your blades are possibly controlled by a tensioned belt. The Toro Time-master is a good example. (see below)

Pulling the bail lever tightens the tension on the belt and makes the blades spin; the tension on the belt may simply need to be adjusted.

Clutch – Three types of clutch, the tractor PTO, the Honda blade clutch, and finally, the belt-type clutch fitted to the Toro Time-master.

Related Questions

What causes uneven grass cutting? The most common cause of uneven grass cutting is an uneven deck. Other possible causes include:

  • Damaged blade
  • Deck wheels are set at different height
  • Tire pressures are low (tractor mower)
  • Deck height needs adjustment (tractor mower)
  • Anti-scalpwheels are missing (tractor mower)

You may find this post helpful:

Hey, I’m John, and I’m a Red Seal Qualified Service Technician with over twenty-five years experience.

I’ve worked on all types of mechanical equipment, from cars to grass machinery, and this site is where I share fluff-free hacks, tips, and insider know-how.

And the best part. it’s free!

Riding Lawn Mower Blades Won’t Engage — How to Fix, Causes, and

If you buy something through our posts, we may get a small commission. Read more here.

It can be frustrating when your riding lawn mower blades won’t engage after powering it on. This won’t only make your day’s work difficult but ruin your other engagements and turn your work session into repair. Several factors can cause your lawn mower’s blades not to turn on. But how can you fix this issue? Our professional team has come up with solutions to try.

Riding Lawn Mower Blades Won’t Engage

Taking care of the lawn is made easy with a riding lawnmower. Like every other machine, you don’t expect it not to develop faults. From the belt to the battery, things can cause the riding lawn mower blades not to engage even when the mower blades are fully sharpened. When these problems arise, our technical expert advises that you should do the following.

Refer to Manual from Manufacturer

One of the first things to do when you discover that your mower’s blades won’t engage is to refer to the manufacturer’s manual. Lawnmowers differ from manufacturer to manufacturers, so as their manuals. You won’t expect a Craftsman mower manual to be exactly the same with Husqvarna, Cub Cadet, or Ryobi. For this reason, you must refer to the manual whenever the blades won’t turn or if you notice any fault.

Inspect Belt

One of the reasons why the blades on your newly purchased Troy Bilt lawnmower may not engage is the belt. It’s either stretched or too loose, worn-out, or damaged, causing it to fall off easily. It could also snap out of position, especially if you tried to cut more grasses at a time that’s beyond its capacity.

The deck belt, located under the operator’s seat, works by engaging and disengaging the mower’s blade. The belt runs through a pulley system and spins the blades. If it has become damaged, the blades won’t engage.

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Before carrying out any replacement, you should inspect the belt first in case your Cub Cadet mower has belt that keeps coming off. The configuration depends on the model and manufacturer, but most lawn mowers have the same design. Reduce the deck to its lowest setting and check out if it’s damaged or has accumulated grasses.

The belt must be inspected at least every six months. This way, you won’t be surprised and frustrated when you want to take care of the lawn.

Replace Belt, Cables, or Clutches

If you notice any damage or excessive wear on the belt during the inspection, it is advisable to address the issue by replacing it. Similarly, if the belt appears loose or excessively stretched, it is recommended to return it to ensure optimal performance.

If the blades don’t still work even after replacing the belt, you should check the blade cable. The cable is made up of metal with cast metal ends, a plastic sheath, and a bracket. If the metal ends are damaged or the cable gets kinked, you should replace it immediately.

You can do the same to the clutches if you find any of the parts damaged. Lawnmowers have clutches that shut off the blades while the engine is running. This part can wear out over time, and when they do, they won’t be able to power the blades.

It’s necessary that you inspect them for proper diagnosis. Disassemble the mower to monitor the clutch better.

If any of the parts that make up the clutches develops a fault, the blades won’t engage. It means you should replace them.

Check Pulley

The pulley could be another reason why the riding lawn mower is having issues causing the blades not to engage. The mower’s pulley controls the tension in the drive belt, which in turn turns the blades. If the pulley freezes and doesn’t rotate, the blades won’t engage.

This is why you need to check the pulley to know its state. If it’s frozen, then you should replace it. You should also investigate if other pulleys on the deck are okay [1].

Check Power Source/ Battery

Lawnmowers use the PTO (Power Takeoff) clutch mechanism to engage the blades. PTOs are either manually operated or electric. Batteries run the electric PTOs.

If the battery has a weak charge or is dead, it won’t power the blades. So, if the blades refuse to engage after powering it on, ensure that you check the battery. You must fully charge the lawn mower battery, and if it’s faulty, you should replace it with a new one.

Tips and Reminders

Here are some tips and reminders you must have at the back of your mind when engaging the mower blades.

  • Check if the deck belt is installed properly.
  • Make sure that you charge the battery fully if the mower blades are electrically powered.
  • Ensure the deck is lowered to the desired height before starting it.
  • Allow the engine to warm up for a few minutes before using it. Replace all damaged belts, cables, and clutches after inspection.

Why won’t my riding mower blades engage?

Even if you have a reverse threaded mower blade, your riding mower blades won’t still engage if the clutches are broken and the cable is damaged. Additionally, if the deck belt is damaged, the pulley system is frozen, and the battery has a weak charge, the chances are that your riding mower blades won’t engage.

How do you engage the blades on a riding lawn mower?

To engage the blades on a riding lawn mower that’s manually operated, turn the key clockwise to power it on, increase the throttle to half speed, and allow the engine to warm up for two minutes.

Then, lower the mower to the preferred cutting height. Push the lever to the right of the steering to engage the blades.

It’s the same if you want to engage a lawnmower with electric blades, except that you don’t have to push the lever to the right of the steering to engage the blades. Just pull up on the yellow Power Takeoff switch to the right of steering.


Lawnmower blades are liable to damages, so it’s typical for them to have issues. However, the level of damages depends on how often you use the mower. This is why carrying out periodic inspections is necessary to prevent escalating the damages. With these practical solutions explained, you can fix the issue that arises.

If you are unable to fix them, contact a professional or if warranty still covers your lawnmower, contact the brand’s customer service. Some manufacturers that have good customer support include Husqvarna, Craftsman, Cub Cadet. and John Deere.