Lawn Mower Blade Spinning But Not Cutting – Why And How?

Lawn mower blade spinning but not cutting? Meanwhile, the lawn mower’s engine is still running and operating normally. This is so confusing!

It’s great that you’re here to join us in solving a very common lawn mower question. Most people will feel confused when faced with a situation where the blade is still spinning but cannot cut the grass.

Is this because the knife is not sharp for cutting grass or is the distance between the blade and the grass not suitable for cutting? Let’s find out some causes related to the operating mechanism of the blade in the lawn mower.

Lawn Mower Blade Spinning But Not Cutting – What Is The Cause?

One of the most common causes of blades turning but not cutting in lawn mowers is the motor, belt, or pulley. However, determining the exact cause depends on whether the lawn mower blade is directly or indirectly connected to the motor

Direct Connection Lawn Mower

A direct connection lawn mower is a blade that connects directly to the engine by the connection of a screw to the crankshaft. So the only reason the blade is spinning but not cutting the grass in this situation is definitely that the blade is loose.

If the connecting pin is loose, the blade will look like it is spinning when the engine is running. However, it will be stopped immediately upon contact with grass. Then when you lift it up, the blade keeps spinning causing this confusing situation.

To remedy this situation, you can remove the lawn mower starter, including the spark plug and deck. If you rotate the blade without the crankshaft moving, you need to tighten the screws between the blade and the crankshaft.

lawn mower blade spinning but not cutting

Indirect Lawn Mower

Indirect lawn mowers are motorized that will attach to a series of pulleys and deck belts. In this situation, you need to check both the pulley and belt system because they work together to create the blade mechanism that rotates and cuts the lawn.

Is the blade installed correctly? This is the first question that you need to check. If the blade is already in the correct position, let’s check out some specific causes below.

Is the belt too wide?

Since the pulley and belt work together to make the machine rotate and mow the lawn, you need to check if the belt is stretched. If the belt is tight and in place, the cause is the blade. However, it is stretchy and loose, which is caused by the belt being overstretched.

Did the belt fall out of place?

If the belt has fallen out of place, you need to check for several potential causes. Make sure that the pulleys remain firmly connected and in their original fixed position. In addition, the pulley on the drive shaft and the blade must be firmly connected and the guide pulley must rotate freely.

At the same time, check if the pulley wire is stretched, the spring is loose, and the parts are not connected.

Some of the issues you need to check for include:

  • Blade position
  • Belt Condition (Sturdy or Loose)
  • Deck belt position
  • Pulley operation
  • Springs are tense or loose

Read more: How To Save Grass That Was Cut Too Short?

How To Fix The Blade Rotating But Not Cutting?

After you’ve learned some of the basic causes of your lawn mower spinning but not cutting, you can come up with some remedies below.

Tighten The Loose Blade

A loose blade won’t be able to cut grass while it’s still spinning since there’s no downforce from the motor. First, you need to tilt the lawn mower in the correct direction for easy access to the blade. Use a wrench or special tool to tighten the center pin.

Adjust The Belt Tension

Some lawn mowers will have an option to adjust the belt tension after a long period of operation. You just need to use a screwdriver or a small wrench to adjust the belt tension.

In particular, you should not put too much pressure on the belt as it can lead to new pulley problems or even break the lawn mower belt.

Replace Worn Belts

To replace a new belt, you need to remove the old belt by cutting it or removing it from the pulley because it is stretched and loose. Use gloves to avoid direct contact with belts and pulleys that could injure you.

Then you replace the new belt in the same position as the old belt. This job can take time if your lawn mower has a lot of pulleys. Try to thread it into a fixed position without causing it to stretch due to strong pulling.

Replace New Pulley

The pulley needs to be replaced when it is loose, or the bearing is damaged or stuck. First, you need to remove the belt, then the pulley. Use specialized tools such as screws, wrenches, and adhesives.

To ensure that the new pulleys do not loosen due to the constant vibrations when the engine is running, you should use adhesives to bond them together.

Replace The New Spring

Springs will also be stretched and loose after the lawn mower is operated for a long time without maintenance. To replace a new spring, you need to be skilled at removing and installing the belt.

After removing the belt, you will find the spring hanging loosely in its holder, so it will be easy for you to replace it with a new one since one end of the spring is hung over the pin or through the hole. Lift the old spring out of place, then place the new spring by attaching the 2 ends to the pin or hole.


There are several underlying causes of a blade turning but not rotating whether it is a pulley, belt, or motor. First, you need to determine whether the blade connects directly to the motor or the pulley and belt.

If the blade is directly connected to the motor, the leading cause is a loose blade. So you just need to tighten the screw between the blade and the motor for it to work.

If the blade is indirectly connected to the motor via a pulley and belt, then you need to check the position of the blade, the stretch of the belt, pulley, or spring. Adjusting belt tension or replacing pulleys and springs will help you overcome this situation.

Do not forget to use labor protection tools such as gloves, wrenches, screwdrivers, and specialized adhesive scissors to overcome this situation.

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