How to Troubleshoot Gas Lawn Mowers

A number of things that go wrong with a lawn mower can be repaired by you.

Lawn mowers break down over time for a variety of reasons. Some regular maintenance can keep you from experiencing a broken mower just when you need it. Checking a mower that is already experiencing problems can lead to easy solutions for the average owner, but some repairs call for a professional.

Things You'll Need

• Stiff brush
• Oil
• Solvent
• Water
• Detergent
• Wrench
• 2-by-4-inch wood
• Compression gauge

Instructions

1. Clean grass and lawn debris from the air intake screen, muffler and oil filler if you notice that the lawn mower is acting sluggishly. Use a stiff brush to clean away debris. Remove the screen so that you can clean the flywheel fins.

2. Check the oil level to make sure you've got enough oil for the engine to operate. Pull out the dipstick to test for oil level in some mowers. Open the oil fill cap if your mower is not equipped with a dipstick. Make sure the oil reaches the high-level mark, and add oil if it doesn't.

3. Locate the cables attached to the clutch and throttle control. Lubricate the exposed cable and the pivot points with a couple of drops of oil.

4. Check the spark plug for signs of dirt buildup or a cracked porcelain insulator. Clean a dirty spark plug with a commercial solvent and a wire brush. Replace a spark plug that has a cracked insulator or if the electrodes have become rounded.

5. Inspect the lawn mower engine's air filter. Lightly smack a paper air filter against any hard surface to dislodge the dirt. Wash a foam filter with water and detergent.

6. Look over your lawn for signs of blade problems. Vibration and torn grass indicates a nicked blade. A dull blade tears grass rather than cutting it. A twisted blade will unevenly chop your grass. Disconnect the spark plug and use a 2-by-4 to wedge the blade so that it remains stationary. Loosen the bolt and check the blade for signs of damage.

7. Insert a compression gauge into the spark plug hole and test the starter if the engine is difficult to start or reveals an increasing loss of power. Consult the service manual of your specific model of mower for information on what the normal compression should be. Remove the compression gauge if the reading is lower than this normal figure, add engine oil and test again. An improved compression figure points to worn piston rings and the need for overhauling the engine. A continued low compression figure points to cracks in the gasket or damage to the valves. Cracked gaskets and damaged valves should be repaired by a professional.

Tips & Warnings

• Do not do any repair work to your lawn mower with the engine running.

References

• Repairfaq.org: Lawn Mower Troubleshooting
• "Reader's Digest New Fix-It-Yourself Manual;" Joseph Gonzalez, Ed.; 1996
• "Yard and Garden Owners Manual;" Marilyn Rogers, 2005