Tips, Tools & Home Improvement

Why is My Lawn Mower Making a Loud Noise?

Don’t pay attention for a short moment when mowing the lawn and the knife crashes into a stone or other hard obstacle. As a result, the mower makes loud, rattling noises. This guide explains how to solve the problem in a detailed and practical way.

Damaged cutter bar increases the noise level

The blades of a lawnmower are not prepared for a violent impact on stones and similar obstacles. A single collision is enough to seriously damage the cutter bar. Loud crackling noises and strong vibrations are the results. Adversity does not mean, of course, that you dispose of the entire lawnmower. By replacing the stripped cutter bar, you can eliminate the problem.

New lawnmower knife lowers the noise level – so the change is successful

To replace the damaged cutter bar, you need a new lawnmower blade and a wrench that match the type. Turn off the fuel tap on the petrol mower and pull the plug from the spark plug. Pull the power plug on the electric mower and remove the battery on the cordless mower. How to change the lawnmower blade correctly:

  • Tilt the petrol-powered lawnmower up with the carburetor
  • Put on gloves and block the cutter bar with a piece of wood
  • Use the wrench to remove the old lawnmower knife including washers
  • Hold the knife and remove the piece of wood
  • Pull off the cutter bar with a rotary movement

Place the new lawnmower knife on the screw opening. First, use two fingers to tighten the screws on the washers so that they no longer fall down. Then pick up the wrench to tighten the screws. Ideally, use a torque wrench to screw the knife exactly according to the manufacturer’s instructions. For safety reasons, we recommend using new screws and washers.

Finally, put the lawnmower upright again. Open the fuel tap on the petrol mower and replace the spark plug connector. Put the battery back in your cordless lawnmower.


If a collision of the lawnmower blades with an obstacle that can be ruled out as the cause of the noise, you should thoroughly clean the lawnmower once. Also include the air filter and the spark plugs, as deposits of dirt particles drive up the noise level of the engine.

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