What Is Diesel Bug?

Also known as microbial contamination, is a common problem in diesel fuel systems. It is caused by the growth of microorganisms, such as bacteria and fungi, in the fuel tank. These microorganisms can clog filters, corrode metal surfaces, and degrade the quality of the fuel. In this article, we will explore the causes of diesel bug and the various treatment options available.

What Causes It?

Diesel Bug

There are several factors that can contribute to the growth of diesel bug in a fuel system. One of the main causes is the presence of water in the fuel tank. Water provides a perfect environment for microorganisms to thrive, as it contains nutrients and oxygen that they need to survive. Water can enter the fuel tank through condensation, leaks, or contaminated fuel.

Another factor that can contribute to the growth of diesel bug is the quality of the fuel. Low-quality fuel may contain impurities or contaminants that can encourage the growth of microorganisms. In addition, if the fuel is stored for long periods without being used, it can become stale and provide a breeding ground for diesel bug.

With the nature of the slow-paced life on the canals and rivers and the large tanks we carry narrowboats can be at high risk of getting diesel bug in their fuel. This goes for any diesel fuel tank that does not have a high turnaround of fuel being used.

Treatment Options

There are a number of treatment options available, and the choice of treatment will depend on the severity of the contamination.

  1. Biocide treatments: Biocide treatments are the most effective way to treat diesel bug. These treatments are designed to kill the microorganisms that cause the contamination.
  2. Fuel polishing: Fuel polishing is a process of removing water and contaminants from the fuel tank. It involves circulating the fuel through a series of filters and separators that remove debris and water. Fuel polishing can help remove diesel bug, but it may not be as effective as biocide treatments.
  3. Tank cleaning: If the contamination is severe, it may be necessary to clean the fuel tank. This involves draining the tank, removing any debris, and cleaning the tank walls and floor. Tank cleaning can be a complex and expensive process, and it should only be done by a professional.

How to Treat Diesel Bug Using Marine 16

Marine 16 is a popular treatment for managing the issue of diesel bug, a collective term for microbial contamination such as bacteria, yeast, and mould, in fuel systems. Here’s a consolidated guide on how to treat it with Marine 16:

  1. Understanding Marine 16: Marine 16’s Diesel Bug Treatment is a broad-spectrum biocide designed to prevent and eliminate microbial contamination in diesel fuel. The product is well-regarded and used by reputable organizations like the RNLI, The Royal Marines, Sea Start, and River Canal Rescue.
  2. Dosage:
    • For preventive measures: A 100ml bottle of Marine 16 is sufficient to treat 2000 litres of fuel, maintaining a concentration of 50 parts per million (ppm).
    • For serious contamination: The dosage should be increased to 100ml for every 100 litres of fuel, achieving a concentration of 1000 ppm. This dosage guideline ensures effective treatment, whether you are looking to prevent or eradicate diesel bug​.​​
  3. Application: The treatment disperses into both water and fuel phases in the tank, remaining active for over a year at both high and low temperatures. This means that once applied, Marine 16 will continue to protect your fuel system for a considerable period.
  4. Safety Precaution: Overdosing with Marine 16 is not harmful to your engine. However, it’s essential to manage water in the tank, as diesel bug thrives in the presence of water. Regular draining of water from the tank, at least once a month, is advised. If your tank lacks a drain plug, consider acquiring tools like a Diesel Dipper to remove water while the boat is underway.

By adhering to the proper dosage and application instructions, along with regular water management, treating diesel bug with Marine 16 can be a straightforward and effective process.

This can be fixed by yourself but if matters persist or worsen seek advice from a professional. If left alone this can seriously damage your engine.

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Prevention of Diesel Bug

Prevention is the best way to avoid contamination.

  1. Keep the fuel tank clean and dry: Make sure the fuel tank is free of debris and water. Water can be removed from the fuel tank by draining the water separator regularly.
  2. Use high-quality fuel: Use fuel from a reputable supplier that meets the necessary standards. High-quality fuel contains fewer impurities and contaminants that can encourage the growth of diesel bug.
  3. Add a biocide treatment: Adding a biocide treatment such as marine 16 to the fuel on a regular basis (every 6 months to a year if no problems are showing).
  4. Keep your fuel tanks full: A full tank minimizes the amount of air, and consequently, the amount of moisture that can condense and accumulate at the bottom of the tank. Microbial growth occurs at the fuel-water interface, and reducing water in the tank minimizes the risk of contamination. This is especially true on the canal system in narrowboats that have large fuel tanks and a slow turnaround of fuel.
  5. Educate Yourself: Understanding the nature of diesel bug, its causes, and signs can equip you with the knowledge to take preventative measures proactively.

The video below shows the process of having your fuel polished to get rid of diesel bug.

Conclusion

Diesel bug is a common problem in diesel fuel systems that can cause damage to the engine and reduce the quality of the fuel. Treatment options for diesel bug include biocide treatments, fuel polishing, and tank cleaning. Prevention is the best way to avoid the problem and this can be achieved by keeping the fuel tank clean and dry, using high-quality fuel, keeping your tank full and adding a biocide treatment to the fuel on a regular basis. If you suspect that your fuel system is contaminated, it is important to take action as soon as possible to prevent further damage.

There are many resources and marine engineers available to provide advice and services to prevent and treat diesel bug. If you are unsure of how to proceed speak to a professional.

If you have any questions about diesel bug you can ask away in our NEW Boat Maintenance Forums Here

Let us know how you dealt with it in the comments below.