Spark Plug Maintenance

Regular maintenance keeps your John Deere equipment running quietly and efficiently. If your John Deere lawn mower, snow blower, or other outdoor power equipment won’t start, a damaged spark plug may be the problem. Worn or dirty spark plugs cause issues for your machine, so be on the lookout for these as well.

As a rule of thumb, you should check and/or replace the spark plug on your small engine machine every year. Also check the spark plug every season or every 25 hours of use to determine whether it should be replaced. If your John Deere equipment won’t start, check and/or replace your spark plug.

To check for a damaged spark plug:

  • Turn your John Deere machine off and allow the engine to cool to the touch. Disconnect the spark plug wire to prevent accidental starting.
  • Blow or clean off the area around the plug with compressed air or a brush, making sure the area is clean. This will prevent debris from getting in the combustion chamber when removing the spark plug.
  • Remove the spark plug with a spark plug socket and clean any deposits from the plug.
  • Use a wire brush or spray-on plug cleaner to remove the deposits, or a sturdy knife to scrape off tougher deposits.
  • Check the spark plug for cracked porcelain, electrodes that have been burned away, or stubborn deposits. If you find any of these issues, change the spark plug.
  • Check the spark plug gap and adjust if necessary. Many manufacturers package new spark plugs with the cap pre-set, but it is still a good idea to double-check the gap and torque according to your John Deere owner’s manual.
  • If the spark plug is in good shape, re-attach. Make sure you don’t over-tighten the plug when replacing it.
  • Reconnect the spark plug wire and start your machine’s engine.

To replace spark plugs:

  • Disconnect the spark plug wire and clean the area around the spark plug.
  • Use a spark plug socket to remove the spark plug.
  • Check the gap on the new spark plug and replace it.
  • Tighten the spark plug but don’t over-tighten it.
  • Reconnect the spark plug wire.