Lawn Mower1/05/2024

How to check and replace a spark plug in your lawn mower

In order for your lawn mower to function optimally, make sure that the spark plug is clean and working properly. If the spark plug is dirty or damaged, this can cause issues with starting your walk-behind mower, or you can experience loss of power while using it.

How to check and replace a spark plug

Check the spark plug if the engine

  • is low on power
  • is not easy to start
  • does not operate correctly at idle speed

For this you will need:

  • A cloth
  • A spark plug spanner
  • A steel brush
  • A new spark plug, if your old spark plug is damaged; make sure to use the right type of spark plug for your lawn mower engine model.
    CAUTION: Always use the correct type of spark plug. Using an incorrect spark plug can damage the product.
  1. Remove the ignition cable.
  2. Remove the spark plug using a torque wrench.
  3. Examine the spark plug; replace it if the electrodes are burnt or if the insulation has cracks or is damaged.
  4. If the spark plug is not damaged, clean it with a steel brush.
  5. Measure the electrode gap and make sure it is correct; refer to the operator's manual for the correct electrode gap for your walk-behind mower model.
    How to set the spark plug gap on your lawn mower
  6. Put the spark plug back in if it is not damaged, otherwise use a new spark plug of the same type. Turn it until it touches the spark plug seat.
    CAUTION: Spark plugs that are not tightened correctly can cause damage to the engine!

How to decrease dirt buildup on a spark plug

  • Make sure that the fuel mixture is correct
  • Make sure that you use the correct oil and have the correct oil level
  • Make sure that the ignition cable is fully connected and that there is not debris around it
  • Make sure that the air filter is clean
    How to clean or replace an air filter on your lawn mower
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