Fleet Maintenance: Fuel Tank Preparation for Long-Term Storage

Quick Summary:

• The Rule: Always fill the fuel tank to 100% capacity before parking a truck for more than a week.
• The Enemy: Air inside the tank leads to condensation (water) and oxidation.
• The Risk: Water breeds bacteria (“diesel bug”) and causes pitting corrosion in aluminum tanks.
• The Expert: Advice provided by Andrey Romanov, Commercial Director at ITALON.

As fleets prepare for seasonal rotation or extended downtime, ITALON has released a technical advisory addressing a common maintenance error. Andrey Romanov, Commercial Director of the company, emphasizes that leaving “air space” in a fuel tank is the primary catalyst for fuel system degradation.

The Physics of the “Empty Tank” Problem

According to Romanov, the danger lies not in the fuel itself, but in the empty space above it. When a truck is parked with a partially empty tank, the following process occurs:

1. Temperature Fluctuation: As ambient temperature drops at night, the metal walls of the tank cool down faster than the air inside.
2. Dew Point: Moisture in the trapped air condenses on the inner walls of the tank.
3. Water Accumulation: Droplets roll down into the diesel. Since water is heavier than fuel, it settles at the bottom.

“There will be no corrosion, no air entering the fuel system, and no condensation,” Romanov states, explaining the benefits of a full tank. By displacing the air volume with diesel, you physically remove the source of moisture.

Aluminum Tanks: Rust vs. Oxidation

While modern European trucks (like the one featured in the video) are equipped with aluminum tanks that do not “rust” in the traditional sense, they are highly susceptible to oxidation and pitting corrosion.

• The Reaction: Water reacting with aluminum creates aluminum oxide (a white powder).
• The Damage: These particles clog fuel filters and damage high-pressure injectors. Furthermore, the water interface promotes microbial growth (the “diesel bug”), which creates acidic sludge.

Protecting Your Fuel Sensors

For ITALON clients, this maintenance step is crucial for the longevity of capacitive fuel level sensors.
Water accumulating at the bottom of the tank has a high dielectric constant compared to diesel. If the sensor probe sits in water:

• Readings become erratic or show “full” incorrectly.
• In winter, this water layer freezes, potentially damaging the sensor tube.

Conclusion: The cost of filling a tank is significantly lower than the cost of flushing the fuel system, replacing filters, or recalibrating sensors after downtime.

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