Fuel Filter Problems in Cold Weather

The Filter Guys

Encountering poor quality or unconditioned fuel is inevitable, so some precautions should be made when operating in cold weather. Depending on the severity of winter operating conditions, many operators may choose to protect their equipment through the use of fuel additives, fuel heaters, and fuel water separators.

I use a good cold flow improver, so why do I continue to have so many problems in the winter?

Cold flow improvers, by design, stop small diesel fuel crystals from growing into large diesel fuel crystals (also known as gelling). This in turn lowers the temperature at which the diesel can still flow and be used in the fuel system. With today’s HPCR engines, filters are becoming more efficient, and the smaller diesel crystals that used to pass through filters now get trapped just as particulates do. This can cause premature plugging of the filter and decreased life. Most fuel related winter problems can be avoided using a #1 diesel or a winterized diesel blend.

Engine Power Loss

Diesel engine power loss during winter operation is a common occurrence. Unless there is a component failure within the engine, the problem can usually be traced back to paraffin crystal formation in the fuel which restricts the flow through fuel filters. Freezing temperatures can also cause emulsified water to form a fuel/ice slush, further restricting filters. Often, fuel filters are blamed for the problem when, in fact, the problem is caused by the effect of cold weather on grade #2 diesel fuel.

Cloud Point

The Cloud Point is the temperature at which paraffin or wax, which is naturally present in diesel fuel, begin to form cloudy wax crystals. When the fuel temperature reaches the cloud point, wax crystals flowing with the fuel coat the filter and quickly reduce the fuel flow, starving the engine. Typical cloud point temperatures range from -18°F (-28°C) to +20°F (-7°C), but may occasionally be as high as +40°F (4.4°C). Grade #1 diesel fuel (or kerosene) contains very little paraffin, and therefore has a cloud point near -40°F (-40°C).