A riding lawn mower is a major investment, and as such, it should be well maintained throughout the mowing season to ensure there are no major breakdowns. One often overlooked element of maintenance on a riding lawnmower is the mower deck, the housing that holds the blades. If the mower deck is uneven, your grass cutting will also be uneven. An uneven mower deck will also cause the blades to wear out quicker, costing you more time and money than a simple leveling of the deck.
Engage the parking brake of the mower to prevent the machine from rolling while working on the deck.
Disengage the clutch, and remove the mower key in the "Off" position.
Disconnect the spark plug wire from the spark plug, and move the wire to a position where it will not come in contact with the spark plug while you're working on the mower.
Raise the mower deck to the highest position using the height lever at the side of the mower.
Fill the tires of the mower to the highest pressure possible so that the tires are even.
Position the blades of the mower so that they are facing left to right, and take a measurement from the tip of the blade to the ground. Subtract the two measurements from each other to get the difference in height between the two blades.
Adjust the mower deck in front of the wheel by using a crescent wrench to lower the lift link lock nut. One full turn of the nut will adjust the mower deck about 3/16 inch. Turn clockwise to raise the mower deck and counterclockwise to lower the deck.
Measure the blade on each side to make sure the blade is even.
Rotate the blades of the mower front to back, and take measurements from the bottom of the blade to the ground.
Loosen the jam nut on the front of the mower deck to access the adjustment nut, which sits right behind it. Turn counterclockwise to drop the front of the mower deck and clockwise to raise it up.