Contaminated Diesel Sample

Water, Condensation & Rust

Heavier than fuel is found under the fuel at the tank bottom.

Bacteria & Fungi

Heavier than fuel but lighter than water and will be found at the fuel/water interface as shown in the photo.

As much as 90% of the upper fuel in a storage tank may not be contaminated if left undisturbed.

CONTAMINATED DIESEL FUEL

Contaminated fuel can damage your engine. Today’s diesel engine manufacturers call for fuel to meet or exceed ISO cleanliness levels of 18/16/13 with a water content of less than 0.05%. Not long ago diesel engines were simple and inefficient. They emitted smoke, and burned high sulfur fuel which contained as much as 5,000 parts per million of contaminants. The older diesel injection systems only used about 1⁄2 the fuel pressure modern engines do, and older injectors send the fuel through much larger passages. If there was a little moisture in the storage tank, the high sulfur content killed most of the filter clogging bacteria and fungi. Today’s diesel fuel is ultra-low sulfur, about 15 parts per million, which allows filter clogging bacteria and fungi to grow rapidly if any moisture is in the fuel storage tank. Modern diesel engines use high pressure, 27,000 to 35,000 psi fuel injectors with tiny fuel passages which are easily clogged with dirty fuel and damaged by water. The old-style fuel filters and gravity water separators that remove 75% to 99% of the contamination are not sufficient for today’s diesel engines. Magnets and filter-less devices won’t clean fuel to ISO 18/16/13 or remove water to less than 100 PPM.

Water & Gasoline

Water in gasoline doesn't just cause issues in the cylinder; it can easily damage injectors if it expands rapidly in the injector tip (due to the inherent heat of the injector).

If water sits in the fuel system for a long period of time, it can even cause rust in your fuel system.