Power loss in diesel engines when operating in the winter is a frequent occurrence and source of the complaint. The issue is typically caused by paraffin crystal formation in the fuel, which restricts flow through fuel filters unless there is an engine component failure. Any emulsified water can congeal into a fuel/ice slush at freezing temperatures, further obstructing filters. When cold weather is to blame for a problem, it is frequently assumed that fuel filters are to blame.

The temperature at which paraffin, which is a naturally occurring component of diesel fuel, starts to crystallize into cloudy wax, is known as the Cloud Point. These wax crystals flow with the fuel as it reaches the cloud point, coating the filter element and drastically reducing fuel flow, starving the engine. Cloud point temperatures typically range from -18°F (-28°C) to +20°F (-7°C), but they can also rise as high as +40°F (4.4°C) on rare occasions.

The pour point is the temperature at which the fuel’s paraffin crystallizes to the extent that it gels and becomes flow-resistive. Pour points differ as well, but they typically happen between 10°F (5.6°C) and 20°F (11.1°C) below the cloud point.

Solving the problem

Most fuel-related winter problems can be avoided if diesel or a winterized diesel blend is used during winter conditions. However, it is inevitable to run into low-quality or unconditioned fuel, so when operating in cold weather, some safety measures should be taken. Many operators may decide to protect their equipment by using fuel additives, fuel heaters, and fuel water separators depending on how severe the winter operating conditions are.

Warning: Never mix alcohol or gasoline with diesel fuel to improve performance in cold
weather. The practice endangers the fuel injection system and raises the risk of
explosion.

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