How To Repair Lawn Mower With Excess Vibration

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If your mower begins to vibrate excessively, stop the engine immediately. This is usually a sign that the mower blade is damaged or out of balance. The vibration is a result of uneven weight distribution at either end of the blade while it spins (the same way a washing machine with a load that is distributed unevenly will knock around and make more noise than usual). This can be caused by a damaged blade, or one that has been sharpened incorrectly and is out of balance. If you suspect your mower is vibrating excessively due to an issue with the blade, inspect the blade for damaged and test for balance. If it is damaged, replace it. If it is out of balance sharpen the blade so it is balanced or replace it. Testing a blade for balance is as easy as hanging the blade on a nail driven into a wall through the center hole. The heavy side of the blade will drop lower than the lighter side. Continuing operation with an issue such as this could cause irreparable damage to the engine, and in some causes could cause injury to the operator.


Another cause for excessive vibration during the operation of a mower is that the crankshaft is bent. Much like damage to the blade, this can be caused by the mower suddenly striking something solid that it is not able to move past (rocks or a tree stump, for example). This sudden stop can cause damage both to the blade as well as the crankshaft. A bent crankshaft (even one that is just slightly bent) can cause excessive vibration when the mower is running, as the spinning blade will be unbalanced. This can be dangerous if not addressed immediately. If you believe your blade or crankshaft has been damaged and it is causing excessive vibration while operating the mower, discontinue use immediately and have the mower serviced by a professional.

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