How to Troubleshoot a Tecumseh Lawn Mower

Place the lawnmower on a clean, flat surface when troubleshooting possible problems, as hot oil spills can damage the grass. Don a face mask and gardening gloves.

Change the oil in the Tecumseh lawnmower if it has start-up problems or keeps turning off during operation. Disconnect the spark plug wire from the spark plug before placing the mower's wheel onto two blocks of wood. Enlist a helper to tilt the mower up onto its two hind wheels while you locate the drain bolt situated in the center of its deck. Loosen the plug by turning it in a counterclockwise fashion, but don't remove it.

Place the wheels back onto the wood blocks. Position an oil pan under the loosened oil plug. Turn the plug counterclockwise to loosen it completely, allowing oil to drain into the pan. Replace the plug once the oil is completely drained and tighten with a wrench. Refill the Tecumseh lawnmower with fresh oil, reconnect the spark plug and set it back on the ground.

Replace the filter if the lawnmower fails to start. Remove the oil drain plug and let excess oil collect in a pan. Replace the plug and tighten it. Using an oil filter wrench, turn the oil filter located on the side of the engine and set it aside. Oil the rim of the new filter before replacing it on the mower. Tighten the new filter with a wrench and add oil into the engine according to the specifications on the owner's manual.

Replace the spark plug if it is damaged, rusted or corroded. Sand burned or rusted electrodes until they are shiny again. Using the spark plug gap tool, reset the spark gap according to the specifications on the owner's manual. Bend the upper electrode over the plug and tap it.

Add more oil if the engine of the Tecumseh lawnmower overheats. Lower a dipstick in the oil reservoir to determine the current level. Remove the oil plug located near the top of the mower and pour oil into the reservoir until the dipstick indicates the ideal level for your mower as specified in the owner's manual.