How to turn the bolt to remove a lawnmower blade? (walk and riding)

Change Your Mower Blade

How to turn the bolt to remove lawnmower blade? Secure your mower so it won’t start accidentally, unplug the spark plug boot, turn it over, secure the blade and use a breaker bar to turn the bolt counter clockwise (to the left). This is the quick and dirty answer to the question but there are a lot of details to make the removal go smoothly.

We show you the complete process and focus on how to do it safely. The last thing you want is to try to quickly get the blade off and end up cutting your hand. This happens more than you think.

Follow these tips if you want to learn how to turn the bolt to remove a lawnmower blade.

Push or Self Propelled Mower -Remove the blade safely

Prepare the lawnmower

  • Remove the spark plug boot from the spark plug. For your safety, you should remove the spark plug to prevent the engine from starting accidentally. Most mowers start by centrifugal force, so it doesn’t take long to start the combustion process.
    • To disconnect the spark plug, locate the spark plug book which is usually on the front side of the engine.
    • Pull the boot firmly so it disconnects from the spark plug. You can use your hand to pull it off. No tools needed for this step.
      • Why? This ensures there’s no electrical flare-up in case the spark plug comes into contact with oil or gas & your blade won’t accidentally start up the engine.
  • Next, turn the lawnmower with gas tank and air cleaner facing up to prevent spillage. All mowers are different, so you may want to refer to the user manual before you start the process. Most toro and honda mowers should be turned to the right as shown in the picture below.
  • Then secure the mower blade. You simply wedge a piece of wood between the mower deck and the blade. Any attempt to turn the mower will be difficult. This way you won’t accidentally turn the blade and possibly cut yourself.
  • Put on the socket and socket wrench.

Pro Tip: Use a breaker bar that is at least 20″ long to give you additional leverage on your socket wrench. If the bolt is really stuck on there you should use a longer bar 30″ to give you more leverage.

When breaking the bolt loose it make take a bit of force. You want to make sure you don’t slip and cut your hand. A breaker bar helps provide the extra force while safely loosing the bolt.

Turn the lawnmower blade bolt counterclockwise

  • The bolt is loosened by turning left (counterclockwise) using a 16mm socket.
  • But depending on the model of the mower, the bolt head can be 1/2″inch or 5/8-inch.

The bigger the socket wrench, the more leverage you’ll have. Pay close attention to the position of the blade as you remove it because you’ll mount a new one in the same orientation.

The blade bolt will turn as you turn the socket. You may be forced to use your hand to hold it when loosening. In this regard, you should wear gloves to protect your hands. It’s good to note that some models use blade-lock gadgets to keep the mower in one place. This prevents the blade from rotating when trying to remove the bolt.

The nut may get smaller due to corrosion, so you should use an appropriate tool. For example, a 16 mm socket may be a better fit for 18-20 mm bolt. After that, look for a long-handled ratchet or a breaker bar to assist with leverage. If the tension suddenly becomes soft, the bolt could be stripping the threads. Make sure you wear some garden gloves to reduce skinned knuckles.

Riding Lawnmower process…

Riding lawnmowers are more complicated and much larger that simple push mowers. Make sure you change the blade on a flat surface. Ensure the parking brakes are engaged to prevent the mower from moving when working on it. Generally, you should lift the mower deck to expose the blade.

The best thing to do is to prop it with some kind of weight. For example, you can use a car jack to raise the mower in order to reach the blade and bolt. Or use ramps to drive the mower up on and chock the rear wheels so it won’t roll off.

How to remove rusted and frozen mower bolts

While rusted bolts can be tough to take off, you can tackle the challenge with the right tools. A general rule of thumb is not to force anything. As with any other situation, you must assess the situation beforehand. If the bolt is rusted, try to remove as much rust as possible from the threads.

Use grease and a stiff wire brush to get the job done. The idea is to soak the bolt down to allow the oil to creep into the threads. Just use WD-40 and it will do the job.

Obviously, you should take great care to avoid any damage. Use wielder proof fire blankets to cover the plastic parts and paint. Once you turn off the heat, try to remove the bolt immediately as the heat can dissipate fairly easily. For blades that are tightly seated, you may have to work it up after you remove them.

Lawnmower blade bolt size

The bolt size depends on the model of the mower. It will also determine the size of the socket needed to remove the blades. Be sure to refer to the manufacturer’s manual before you decide to change the mower blade. If the bolt is 15mm you should use a corresponding metric wrench.

Are riding lawnmower blades reverse thread?

Most lawnmower blades are also reverse-threaded. This means that when the blade rotates, it does not loosen the bolt. It’s worth mentioning that not all blades use a reverse thread bolt to secure them. Before you begin the process, find out the direction of shaft rotation.

If the blade in your mower turns clockwise, then it’s a reverse thread. However, if it rotates counterclockwise it has the common threads that tighten when you turn the wrench in a clockwise direction. Make sure you place the bolt in a safe place so that you can easily find it when you’re ready to return the blade.

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Other considerations

Before you change the blades on your mower, make sure you have all the tools you need. Here are the pros and cons of changing lawnmower blades.


  • Sharp blades guarantee a clean cut
  • Increases fuel efficiency
  • Reduces mowing time
  • Increases durability of the mower


• Using the wrong bolt can make the blade wobble

Final thoughts

Does your lawn look torn or ripped after mowing? Well, chances are that your mower blades need to be replaced. This is an easy task as long as you approach it correctly. When you loosen the bolt, you can easily remove the nuts from the mounting bracket. And once you’re done, lower the mower, reattach the spark plug and check the oil level. If you keep the blades sharp, you’ll extend the life of your mower, increase fuel efficiency and achieve a clean cut in your lawn.

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D. Hahn

DIY guru, dad, husband, blogger. When I'm not creating life hacks I'm teaching my kids how to fix stuff after their dad breaks it.

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