Must-Read for Shipowners: 6 Major Engine Failures Possible from Improper Spark Plug Maintenance

Among the many critical components of a marine engine, the marine spark plug is a small but crucial component. As the heart of the ignition system, its working condition directly impacts engine performance and lifespan. However, many shipowners often neglect regular spark plug inspection and maintenance, ultimately leading to serious engine failure. Understanding the six major engine problems that can result from improper spark plug maintenance can help avoid unnecessary repair costs and navigation risks.

1. Difficulty Starting or Failure to Start

When marine spark electrodes are worn, heavily deposited, or have excessive gaps, ignition energy is significantly reduced. This is particularly common in humid marine environments. The engine may require multiple attempts to start, or even fail to start at all, especially on cold mornings or after extended periods at anchor.

2. Lack of Engine Power

If the spark plug ignites unstably, the fuel cannot be fully burned, resulting in reduced engine power output. You may notice a loss of acceleration, a reduction in top speed, or a noticeable power loss under heavy loads. Long-term problems can also increase fuel consumption and operating costs.

3. Abnormally Increased Fuel Consumption

A damaged spark plug can cause incomplete combustion, reducing fuel efficiency by 10%-15%. If you notice your fuel tank draining significantly faster than usual and there's a strong gasoline odor or black smoke emanating from the exhaust, a faulty spark plug is likely the culprit.

4. Engine Shake and Abnormal Vibration

When a spark plug in a cylinder fails, it can cause malfunction in that cylinder and lead to unstable engine operation. This shake is particularly noticeable at low speeds. If left untreated, it can damage the engine mounts and even cause premature wear of other related components.

5. Exhaust Pipe Backfire or Backfire

Inaccurate ignition timing (such as an abnormal spark plug gap) can allow unburned air to enter the exhaust pipe, causing explosions in high-temperature environments and producing a loud "backfire" sound. Even more dangerous is backfire, where the flames travel backward into the intake system, potentially damaging the air filter and even posing a fire hazard.

6. Catalytic Converter Damage (For Vessels Equipped with It)

For modern vessels equipped with exhaust aftertreatment systems, prolonged use of defective spark plugs can cause large amounts of unburned fuel to enter the catalytic converter, causing it to overheat and gradually fail. The cost of replacing a catalytic converter is often dozens of times greater than the spark plugs, a significant expense that can be avoided with regular maintenance.

Preventative Tips:

Check spark plugs every 100 hours of operation or at least annually.

Use marine-grade, corrosion-resistant spark plugs.

Maintain the correct electrode gap.

Clean or replace any carbon deposits promptly.

Keep spare spark plugs on board.