John Deere mowers are high-performance machines and, like any mowers, need regular maintenance to maintain peak operations. Dirty air and oil filters, bad spark plugs and dull blades can reduce the mower's efficiency. A tune-up reduces unnecessary wear on the engine and keeps your mower running. Failure to maintain the engine through regular tune-ups may void the warranty from John Deere. Refer to your owner's manual for recommendations on when to service parts, usually expressed in running hours.
Set a tarp onto a flat surface. Roll your mower onto the tarp and engage the parking brake.
Remove the cord for the spark plug to prevent the engine from starting during maintenance.
Set a drain pan under the fuel filter. Pull the two clips holding the fuel filter to the hoses back from the filter using a pair of pliers. Drain the filter into the drain pan. Replace the old filter with the new filter, the arrow on the filter pointing towards the carburetor. Pull the clips towards the fuel filter to hold it in place. Run the engine to get fuel flowing through the filter. Dispose of the fuel according to the local regulations.
Lower the mower deck and remove it. Each mower deck is removed differently, so refer to your owner's manual. Lift up the mower deck and inspect the blades for wear. Remove the nut from the center of the blade if dull. Remove the blade and replace, or sharpen it. Scrape excess grass from the underside of the deck with a dull paint scraper. Reassemble.
Remove all grass from the air intake on top of the engine. Remove the air filter cover. Remove the paper air filter if dirty. Replace it.
Turn on the engine for a few minutes, then shut it off. Place drip pan under the engine's oil plug. Remove the drain plug and drain the oil. Turn the oil filter with an oil filter wrench. Pour out the oil in the filter into the drip pan. Run a bead of new oil onto the rim of the new oil filter and install it. Clean the air filter compartment with a clean rag. Tighten down the filter on the engine. Refill the oil crankcase.
Remove the spark plug from the engine. Check the plug for cracks or signs of corrosion. Replace the spark plug if necessary.