As iridium spark plugs become worn and dirty, more electrical power is required to produce the spark necessary for ignition. This reduces efficiency and increases fuel consumption – and can eventually lead to misfires and electrical short-circuits. It follows that the cleaner the spark plug’s electrodes, the more powerful a spark the component will produce, at a lower voltage.


Cleaning, gapping, and testing spark plugs regularly improves engine efficiency and reduces the risk of engine failure. In this article, we explain how to clean an iridium spark plug without using specialist equipment.

How Should I Assess The Level Of Fouling And Wear?

Remove the spark plug from the cylinder head . A visual inspection will reveal the level and type of fouling. This will help you diagnose other potential issues with the engine (see below). Check for wear on the electrode tip. If the tip is worn down, the spark plug needs replacing. If wear is minimal, cleaning the spark plug will restore performance.

What Causes Spark Plug Fouling?

Fouling refers to any build-up of carbon, oil, grease, dirt or soot around the spark plug electrodes.

The causes of fouling vary, depending on what gases are been burnt many special gases contain siloxanes which leave a very stubborn deposit on and around the electrodes.

What Is The Cleaning Process?To clean the spark plug, first use a carb spray cleaner to remove gunk, grease, and oil from the electrode tip

  1. Excess grease can be removed with a soft rag/cloth or additional spray cleaning
  2. These two steps are generally sufficient to restore performance. However, if you wish to deep clean your spark plug , ingrained dirt can be removed using a wire brush . Be careful when doing this, as some abrasive brushes can damage the spark plug electrodes and compromise performance.
  3. Re-gap the spark plug to the manufacturers recommendation, replace spark plug washer/ gasket and in reinstall, tighten to recommended torque .

    If performance issues or misfires continue, your iridium spark plugs should be tested and replaced if necessary.

    What Next?

    At R&M Walsh, we stock a wide range of premium spark plugs for industrial gas-fired engines. To discuss your requirements or for a free quote, please contact us!

    Download Your Guide
    Image source: Pixabay

    follow us