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How to Replace a Lawn Mower Blade

A lawn mower is one of the best pieces of equipment to have in your arsenal this spring and summer. However, without a sharp lawn mower blade your machine is defenseless against rapidly growing grass. Since grass grows like crazy this time of year, having easy access to an efficient mower can make all the difference, but it’s not enough to just own a lawn mower. Your machine must undergo regular maintenance and upkeep, and replacing your lawn mower blade is a must so read our step-by-step guide to change the lawn mower blade and get your yard in tip top shape.

Before performing any maintenance on your lawn mower, refer to your owner’s manual for maintenance instructions and safety information. Maintenance instructions vary by model, so depending on your lawn mower model our instructions may vary slightly.

Here’s how to replace a walk behind lawn mower blade.

Before replacing or repairing anything on your mower, please follow these safety precautions: shut off the lawn mower engine and allow it to cool, disconnect the spark plug wire to prevent accidental starting and tuck it out of the way so the wire doesn’t make contact with the spark plug.

To carry out this task, you’ll need these tools: 5/8 socket, ratchet, breaker bar, torque wrench, and a block of wood.

To replace your lawn mower blade, tip the mower over to access the blade but keep the air filter side up to prevent the oil from going into the air filter and carburetor , which will prevent the mower from running when you tip it back over.

To remove the bolt off the bottom of the blade, take your block of wood and wedge it between the lawn mower blade and the frame of the mower.  Make sure it’s good and steady because you’ll be applying force when you loosen and remove the bolt. Once the block is firmly in position, use the 5/8 socket and ratchet to remove the bolt holding the lawn mower blade in place. If you have issues removing the bolt, use a breaker bar twist to loosen the bolt.

Remove the block of wood once the bolt begins to loosen. Set aside your breaker bar and socket, and use your hand to continue twisting the bolt loose. When you’re able to remove the bolt, check for any gnarring or missing threads. If any threads are missing there’s a chance that the bolt could come loose and the lawn mower blade could come off and injure you and others. If your bolt is worn or damaged, purchase a new one before putting it back on the mower.

Now that the bolt has been removed, you may remove the lawn mower blade adapter and the blade itself. Before installing the new lawn mower blade use your scraper to scrape out any type of debris from the mowing deck that can cause the mower not to recycle correctly.

With the lawn mower blade now off of the machine, you can either replace it or sharpen it. Feel free to visit us at any of our locations or order the lawn mower blade online at

When replacing the lawn mower blade, put the blade adapter back through. The adapter has 2 pins on it, and you should put those pins into the lawn mower blade. A lot of blades say “bottom” or “grass side.” When putting the blade back on the mower, make sure the grass side or bottom is facing you.

Put the bolt through the lawn mower blade and the adapter. On the mower, there is a plate that you’re going to bolt it to. Put that bow tie pattern into the lawn mower blade – this helps put the blade in place so when it’s spinning it does not come loose.

Thread the bolt in by hand to prevent t from cross threading, which will cause you to replace the crank shaft. Place the block of wood between the lawn mower blade and the mowing deck housing again. Use your 5/8 socket and torque wrench to torque down the blade bolt. Set your torque wrench for 40 to 50 foot pounds to torque it down.

Once you torque the lawn mower blade on, remove the block of wood and place the mower back on its wheels. Replace the ignition wire and start the mower to check for proper operation.

You May Also Enjoy These Articles:

Types of Lawn Mower Blades

Mower Maintenance

Lawn Mower Maintenance

Buyer’s Guide to Walk Behind Lawn Mowers

5 Lawn Mower Tune-up Tips for Spring

5 Reasons Pre-Mixed Fuel is Best


Why Weingartz?

Weingartz, family owned and operated, began in 1945 as a farm supply store for local Michigan families. In the 1970s, we began to focus exclusively on outdoor power equipment. Over time, we morphed into the “power equipment superstore” that now defines all of our locations. The staff and experts at Weingartz work diligently to provide the best service possible and give honest and helpful advice to each and every customer.

Weingartz also sells parts for all outdoor power equipment at

6585 Dixie Hwy.
Clarkston, MI 48346
(248) 620-5258

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