Grass Buildup in a Lawn Mower Deck

Results of Buildup

• The thick grass buildup underneath the mower deck overloads the mower, clogging the space around the blade and causing it to constantly shut off. The moisture held in the built-up grass clippings eventually lead to rust and corrosion on a deck that is made of metal. The grass and dirt on the deck and blade also prevent the blade from cutting the grass correctly. Instead, the blade ends up tearing the grass, which leads to a diseased, less healthy lawn. If the grass buildup keeps shutting off the lawn mower while you are mowing, especially in thick grass, stop the mower. Remove any built-up grass stuck in the mower's discharge chute, and raise the mower deck. With many mowers, you do this by adjusting a lever on the mower wheels.

Cleaning the Deck

• If you don't already know the location of the carburetor on your mower, consult the owner's manual. To clean the buildup from the underside of the deck, tilt the mower onto one side, with the carburetor on the top. This way the gas doesn't leak down into the carburetor. Disconnect the wire from the spark plug or remove the spark plug entirely to prevent the engine from starting if you turn the mower blade while you're cleaning. Tilt the mower and carefully remove whatever large clumps of grass you can, using your hands, then scrape off the buildup with a stiff brush. Use a scraper or putty knife if the buildup is particularly old or hard to remove. Spray the underside of the deck with a water hose. Make sure you spray the deck underside and not the side of the mower, or you might wet the air filter.

Cleaning Schedule and Tips

• To prevent grass buildup underneath the lawn mower deck, clean it off diligently after every mowing, if necessary. At the very least, you should clean it off at the end of the mowing season before you store it away until the next year. You will probably need to clean it more often than that, especially if you mow with it regularly. Use either a soft detergent or car shampoo and water to clean the deck. After cleaning, spray just a light amount of vegetable oil on the underside of the deck to cut down on the amount of grass building up on the underside of the deck.

Wet Grass

• Avoid cutting grass when it is wet, such as immediately following rainfall. Give the grass sufficient time to dry. If you cut wet grass, it sticks to the deck more easily and builds up a lot faster than dry grass. Even if the mower does not cut off from the buildup of wet grass underneath the deck, it will probably dump out large clumps of wet grass around the lawn as you mow. You may find yourself having to constantly stop and manually remove the large grass clumps from the mower's discharge chute.