Why Is My Mower Deck Cutting Lower on the Side?

Bent Blades

• Before performing any service adjustments on your mower, park it on flat ground, engage the parking brake, put the clutch into neutral, and take the key out of the ignition. Also, unhook the electrical wires from the spark plugs.

  Before adjusting the mower deck, raise up the deck and check the condition of the cutting blades. If these blades have been bent, they can also cause an uneven cut. If the blades look damaged or bent, follow your mower’s procedure for blade removal and replacement.

Check Tire Pressure

• Another common problem that may cause an uneven or a lower cut on one side occurs when the tires don’t have equal pressure in them. Most tires require consistent pressure checks, usually after every 25 service hours. With a tire gauge, unscrew the caps on fill nozzles and check each tire’s pressure. On most tires, the required pressure, in psi, will be stamped along the sidewall. Most often, these indicate maximum pressure. Fill the tires close, within 2 to 5 psi, to this recommendation and make sure the tires are all equal in pressure.

Side-to-Side Leveling

• The mower deck offers a way to adjust it horizontally, or from side-to-side. With mower deck at mid-cutting height, point the blades so they also point from side-to-side. If the distance between the bottom of the cutting deck and the ground is more than 1/8-inch different on each side, the mower deck will need adjusting. This process can vary considerably from mower to mower, but usually involves the gradual loosening of a few bolts and rechecking the measurement.

Front-to-Back Leveling

• The mower deck also offers a way to adjust it from front-to-back. However, the mower blades should be set just slightly higher in the front than in the back. Similar to the side-to-side adjustment, the blades need to be pointing front-to-back, and the operator should measure them at the tip of the front and the tip of the back blade. This will ensure an accurate measurement, and if the front tip isn’t one-eighth to one-quarter higher, the mower deck will cut uneven and lower to one side.