Is your lawnmower crankshaft bent?

Is your Lawnmower Crankshaft bent? Find out now!


Is it normal to have the bent in the crankshaft of lawn mowers? But many of us are confused about telling if the lawnmower crankshaft is bent? For example, you are mowing your lawn and suddenly appear an unusual voice when its something like rock or metal pieces. Usually, we don’t care and restart the mowing process. 

Well, it’s the primary reason for significant damages, including the bent in the crankshaft. It is a problem causing damage, that reduces the working of lawn mowers. 

However, if you are also facing the same issue, this guide is for you. Here we will share, how to tell if the lawnmower crankshaft is bent? Its primary reasons and how to fix it?

Now let’s dive into its details. 

How to tell if the lawnmower crankshaft is bent?

There are a few of the primary reasons for bent crankshaft that you should know. The primary symptoms of a bent lawn mower crankshaft are vibration, grinding noises, starting issues, stalling or uneven cuts during working, and others. 

These are the signs from which you can easily tell your lawn mower crankshaft is bent. So before the query how to tell if a lawnmower crankshaft is bent, you need to know its symptoms. 

Here we will share some common signs and methods for inspection to identify these signs. It will help you understand the issue in your lawn mower and crankshaft. 

Search for the symptoms

Usually, there are two types of issues in the crankshaft of a lawnmower, including excessive vibrations and transmission issues. 

Follow the below-mentioned methods for inspecting the issues as soon as possible. 

Symptom 1 : Excessive vibrations

If you notice the grinding sound in your mower with the high vibration, there must be a reason. Check your crankshaft for its bent. Usually, these are the signs of the bent crankshaft that produce high noise and vibration during mowing. Closely inspect the lawnmower for its voices before and during the mowing work. 

Symptom 2 : Transmission issues

Modern lawn mowers work on the engine, battery power, or gas. It may cause transmission issues, especially during the start and running time. The typical sign of crankshaft bent also leads to messing up in ignition or flywheel hits. 

Symptom 3 : Physical issues

It is also essential to physically inspect the crankshaft and lawnmower for possible issues or damages. 

Here are the four standard methods to physically assess the lawnmower crankshaft:-

Method 1 : Disconnect Spark Plug

It is the first method you can follow to know about the bent in the crankshaft. If you notice the spark in the plug then turn off the mower. Take a marker and mark one end of the mower blade. You can also clump the ruler with your mower edge that touches the crankshaft. Now manually start turning the crankshaft and notice the gap between ruler and crankshaft. You can catch the gap with one rotation. If there is a gap, it is clear that the crankshaft has bent and needs repair. In addition, it’s better to wear safety gloves while performing this inspection. 

Method 2 : Look at the center bolt

Center bolts also help to diagnose the bent lawnmower crankshaft. However, remove the spark plug from the lawnmower and start pulling the starter cord of your mower. When drawing the line, ensure that you have an eye on the bolt that holds the blade and check for any wobbles in it. If you find any wobbles with the moving blade at any side, it is clear that it has a bent crankshaft. 

Method 3 : Tie the brake handle down

It is another inspection method that helps the mower to prevent crankshaft spinning. Tie the brake handle down so that there is no movement. You can use handy materials like rope to avoid the action and then go through observation. Ensure that you park the lawnmower on a flat surface without debris disturbing you during the inspection. However, check for the signs of blade shaking. If you find any wobbles then there is a bent crankshaft. 

Method 4 : Tilt your mower

Here is the last inspection method for bent in the crankshaft. You need to flip the lawnmower and tip it back on the back wheel in this method. You can also take the help of a third person to hold it back with you and maintain the position. Moreover, you can also tilt the lawnmower on the right side and then inspect the crankshaft clear. It will give you the precise inspection of the viewer carburetor and air filter at your front. 

How to repair the bent crankshaft of the lawnmower?

There are many professional services available that help you repair your lawn mower crankshaft. Professionals have special tools that make it easy to fix the crankshaft. 

However, these professionals methods include:-

Method 1 : Shaft Straighteners

Shaft straighteners help repair the bent of the crankshaft. It provides a mechanical press that helps regain the crankshaft’s straight position. It is an efficient automated method to repair lawn mowers. 

Method 2 : Sledgehammers

Sledgehammers also help remove the bent from the crankshaft and regain its original position. It applies the impact force that clears the bent. You may find it more complex than the shaft straightener. 

Method 3 : Replacement of crankshaft

Sometimes the shaft bent in too bad a shape that it is impossible to repair. The only solution for this situation is to replace the crankshaft with a new one. You can replace the crankshaft with easy-to-follow guidelines by professionals. Ensure that your crankshaft is according to the requirements of the lawnmower. It helps you gain the whole working experience better.


Now you know how to tell if the lawnmower crankshaft is bent? It is essential to inspect the crankshaft with different methods and then use the appropriate repairing method. As mentioned earlier, a lawnmower with a bent crankshaft shows vibration, noise, and some other signs. 

We hope this article helps you to understand the bent crankshaft and how to repair it.

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