Noisy Mower Deck on a John Deere L120

Low Tire Pressure

• Whenever the tires on the mower are low on air, the entire John Deere unit will vibrate more and will create excess noise in the mower deck. You can use an automatic or manual air pump to inflate each tire, but make sure the mower is parked and turned off before you inflate the tires. Do not exceed 83 kPa (12 psi) on the front tires or 69 kPa (10 psi) on the rear tires.

Mower Wheels

• Sometimes the mower wheels have been set to the incorrect position, which may also result in noise from the mower deck. Remove the bolt, bushing and nut from each wheel and move the wheel to the bottom hole on the left of the wheel bracket. Reinstall the bolts, bushings and nuts firmly with an adjustable wrench to make sure the wheels are fastened securely to the mower.

Mower Deck Height

• The mower deck may be out of position for the lawn height, creating noise. Push the attachment lift lever, which is located to the left side of the seat, forward until the adjustment lift lever is positioned next to the desired cutting height indicator. Move the mower deck height reminder tab, which is located next to the adjustment lift lever, to the corresponding cutting height. Note that setting 1 corresponds to an approximate cutting height of 1 to 1.5 inches, setting 2 corresponds to a cutting height of approximately 2 to 2.5 inches, setting 3 is for a cutting height of 3 to 3.5 inches, and setting 4 is for transport or storage of the machine.

Mower Deck Debris

• Occasionally, debris or excess clippings can get caught in the mower deck, creating vibration and sound. Park the mower and wait for the mower to come to a complete start before getting off the mower and removing the key. Open the cover on the hopper and look inside at the chute outlet. If necessary, pull the chute out from under the mower deck and clean the chute out to remove excess grass or debris, and then look underneath the mower deck for debris as well. Clean the mower deck as needed, and then reassemble the chute and the hopper cover.