Spark plugs are consumable products and don’t last forever. Cleaning and re-gapping your spark plugs on a regular basis – and addressing the causes of spark plug fouling – will extend their working life and keep your engine running efficiently. Nevertheless, there comes a time when spark plugs should be changed, and it’s useful to know the approximate working life of each spark plug so that servicing can be planned and unexpected downtime avoided.


There is no absolute answer to how long an industrial spark plug will last. A spark plug’s longevity depends on several factors:

1. The make and model of the spark plug – some manufacturers produce better quality spark plugs than others, and some models are designed for a longer service life. Much of this comes down to the quality of the materials used, so it’s always worth spending a little more for a premium spark plug from a respected manufacturer.

2. The type and condition of the engine. Older engines, or more powerful engines, will put greater pressure on the spark plugs, causing them to wear out more quickly than in other circumstances. Keeping the engine in good condition and regularly maintained will maximise the performance and working life of the spark plugs.

3. The state of the spark plugs. Spark plugs lose efficiency as they become fouled by carbon, oil and gas deposits around the electrode. The greater the fouling, the harder the plug has to work to produce enough of a spark to fire the ignition. Eventually, this can wear out the electrode, ruining the spark plug and causing an engine misfire. Keeping your spark plugs clean as part of your regular engine service will maximise their working life. However, some abrasive cleaning methods – such as wire brushing – may damage the electrode and shorten the life of your spark plug.

When Do I Replace My Industrial Spark Plugs?

As every engine condition is different, keeping a log and monitoring when misfires happen due to spark plug failure will help you to become familiar with your engine. You will know when the best time is to replace your spark plugs and, as a result, reduce downtime. This will hopefully help you to meet the expected running hours – changing to a different spark plug may give you more running hours.

Why Is It Important My HT Leads Are Monitored?

Your HT leads should also be monitored; heat from the engine can dry out components and cause flash over or energy leakage, and this could be the cause of misfire and reduce the life of your spark plugs. For this reason, upgrading your HT Leads can help extend running hours.

Find Out More

At R&M Walsh, we stock a wide range of spark plugs, control systems and ignition equipment for a variety of industrial engines. Please browse our website to view our current availability, and call 01782 983376 to speak with one of our knowledgeable advisers.

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