Home Garden

Lawn Mower Engine Tips

Lawn mower engines, though simple, require regular maintenance and repairs to run properly. Most mower engine maintenance revolves around routine inspection and cleaning of associated engine parts. Keeping up with a maintenance schedule ensures you will have limited costs for major repairs over the life of the mower. As the homeowner you can do most maintenance of this type without special knowledge other than the specifications associated with the mower.
  1. Starting

    • You can determine starting issues using a simple troubleshooting process. Spray the carburetor with carburetor cleaner to check the fuel. A popping noise indicates fresh fuel is needed; no noise indicates an airflow problem. Change the air filter and start the mower. Check the spark plug if the engine fails to start. If the spark plug and chamber are good, check the blade and shaft for damage.

      Riding mowers have an additional problem similar to automobiles. Riding mowers have a starter that can fail. Attach jumper cables to the battery and the starter directly. Set the positive and negative cables properly on the battery and set the other positive end on the starter and the negative end on metal as a ground. Start the mower; if the engine fails replace the starter.

    Cleaning and Maintenance

    • Reduce the number and frequency of repairs by using a regular maintenance schedule. Brushing off grass and debris from visible parts such as the blades, engine and deck removes the potential for debris to damage moving parts or hoses. Annual inspections of the carburetor, engine, filters and fuel line for grime or damage allows you to catch potential problems before they occur or become serious. Inspecting blades, plugs and cables before each use ensures no sudden malfunctions occur and alerts you to potential problems.

      Clean carburetors, fuel filters, gas tanks and spark plugs with gasoline. Gas acts as both a lubricant and an abrasive material for removing dirt and grime. Clean fuel lines, hoses and air filters with soap and water because these are more fragile than metal parts.

      Adjust the mower cables and wires leading to the engine according to the manufacturer's specifications. These loosen over time causing improper ratios in power and speed. Tighten bolts and nuts surrounding the engine and engine housing. Vibrations and corrosion cause nuts and bolts to loosen or lose their hold. Moving parts can be damaged through vibrations as they increase in intensity.

    Preventative Measures

    • Minimize future problems with the proper amounts of clean fluid in each chamber at the start of the mowing season. Use the dipstick in the oil and fuel reservoirs to ensure correct amounts of each. Overfilling fuel causes potential for backfires and engine flooding; overfilling oil causes spark plug fouling and ignition failure. Drain all fluids at the end of the season to ensure no spent liquid remains. Fuel or oil left over time hardens into a sludge that prevents moving parts or airflow from properly functioning. Use a fresh spark plug and charged battery to ensure proper ignition each season. Use fresh fuel and oil to eliminate buildup and contaminates within the hoses and engine.

    Common Problems

    • Troubleshoot the engine for basic common problems. Look for cracks, holes or missing parts before disassembly. Check electrical connections, fuel, airflow and vibration due to loose housing and fasteners. Check the springs and cables such as the throttle, choke, governor and brake for tightness. Any loose cables or springs should be adjusted to eliminate more serious issues later.

      Spot potential engine trouble using visual indicators such as smoke and soot. Black smoke indicates fuel problems. Blue smoke indicates oil in the engine or crankcase. White smoke indicates either oil or airflow problems. Listen for audible signals such as sputtering, revving, racing, sudden stalling and backfires. Most often the initial cause of the problem is airflow or electrical related.


    • Turn off the mower and allow the engine to cool down before attempting any maintenance. Disconnect the spark plug and remove it to avoid accidental sparks. Set the mower on a hard level surface to ensure the mower doesn't move and you have access to all sides of the mower.

      Mowing wet, tall or thick grass allows debris to buildup in the engine housing and may cause moisture buildup within the engine. Check the blades for wet grass or grass wound around it as a reason for engine trouble.