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Diesel engine do’s and don’ts for a trouble-free winter

Diesel engine do’s and don’ts for a trouble-free winter

The best solution to cold weather diesel starting problems in your vehicle is to avoid them by being prepared for cold weather before it happens. 

Diesel engines are harder to start in cold weather because they depend on high temperatures created by compression to ignite the injected fuel. 

In fact, it is five times harder to start a diesel engine at 0° F (-17° C) than it is to start one at 80° F (26° C).

The top reasons for this are gelled fuel, cold cylinder walls and electrical failure. There are, of course, many others but addressing these three is a good place to start getting your diesel engine ready for winter weather conditions.

Tips on fuel handling for your diesel engine

  • Do use winter blended diesel fuels which is less likely to gel.
  • Do store full portable diesel fuel cans in a temperature-controlled area to avoid condensation.
  • Do drain the water from the diesel engine fuel filter daily, preferably when the machine is shut down for the day so the water does not sit in the filter overnight.
  • Don't forget to drain the water separator on diesel fuel storage tanks every day.
  • Do fill the fuel tank at the end of the working day, as a full fuel tank doesn't leave room for water to condense overnight.
  • Don't neglect the diesel fuel filter – it's the most common place for fuel to gel.
  • Do change the diesel fuel filter before winter weather sets in. That makes it less likely to freeze and avoids the need to do the job in the cold.
  • Do keep a spare diesel fuel filter and/or water separator on hand. It's often easier to replace a frozen one than it is to thaw it.
  • Do park your diesel truck and equipment in a sheltered location whenever possible. A heated shelter is best, but simply parking your vehicle where the wind can't blow snow and ice under the hood can make a big difference when you start the engine.

Other important fluids beyond fuel for diesel engines

Tips about engine oil

  • Do switch to a lighter weight engine oil in your vehicle during cold weather. A cold engine needs adequate lubrication especially when you start the engine.
  • Don't use engine oil lighter than the diesel engine manufacturer recommends as it may not provide adequate lubrication when the engine is hot.


  • Do check your coolant regularly with a hydrometer. The glycol in your coolant is there for a reason, it doesn't boil off and it lowers the freezing temperature of the mixture.
  • Don't top off the coolant with some plain water. Make sure to use a proper water/glycol mix every time. You do not want water to freeze in your machine or truck engine or radiator.
  • Do pay attention to vehicle temperature gauges and avoid overcooling which can be caused by long periods of idling or excessive airflow. Overcooling can cause poor combustion leading to white smoke, increased fuel consumption, and inefficient aftertreatment system performance.

Diesel Exhaust Fluid

  • Don't store diesel exhaust fluid (DEF) at below freezing temperatures. DEF is about 50 percent water and will freeze.
  • Don't worry about DEF in the tank on the machine; the system automatically circulates engine coolant to thaw it so it's ready for use when the machine warms up to temperature.

Cold Engines

  • Do inspect and, if necessary, check glow plug status and change them if needed. Also review air inlet heaters before cold weather sets in. It's another job more easily done in warmer temperatures.
  • Do consider using engine block heaters if one is installed or installing an aftermarket unit. A warm engine is much easier to start and avoids many of the issues related to cold weather operation.
  • Don't use starting fluid unless the machine or truck engine is equipped with a factory installed kit that precisely controls the amount used. Simply spraying starting fluid into the air cleaner carries a high risk of causing a fire or even an explosion.

Electrical Systems

  • Don't ignore your battery. After a hot summer that encourages corrosion and fluid evaporation the added strain of a cold weather start can kill a battery. A battery can lose 35 percent of its power at 32° F (0° C) and as much as 60 percent at 0° F (-18° C).
  • Do consider using a battery warmer, either a "hot plate" type that slides under the battery or an "electric blanket" type that wraps around the battery will help the battery retain its charge.

Some other considerations

Parasitic loads

Parasitic loads can include: engine and transmission oil viscosity, fan drive, clutch engagement, hydraulic pump engagement, belt drive systems and anything else that's driven by the engine or consumes some engine power. Any parasitic load during cranking can be a major contributor to the engine's inability to start.

Warm-up time

Always let a cold machine or truck engine warm up for at least five minutes before putting it to work. That gives the coolant, engine oil, hydraulic oil and DEF time to come up to operating temperature so they can function efficiently.

Benefits from testing in cold weather environments

Diesel engine builders know their products will be used in virtually every environmental condition found on Earth and they go to great lengths to test them under extreme conditions. 

Perkins, for example, has completed billions of hours of engine tests across different environments including cold testing at a Perkins facility in Arjeplog, Sweden, 100 km from the Arctic Circle where air temperatures drop to -49° F (-45° C).

A modern diesel truck or piece of equipment will start and run under all extreme conditions with very few things going wrong, but ignoring those challenges in your vehicles can be expensive. 

Proactive preventive action may seem like an extra expense or time spent on something that isn't a problem, now, but it makes economic sense in the long run. 

The consequences of ignoring winter diesel fuel problems in your equipment or truck can range from losing all or part of a day's work to repairing expensive engine damage. 

Simple steps like keeping your fuel tanks and cans filled, plugging in heaters, using weather-appropriate fuels, strategic equipment parking and regular battery care can all make a big difference in how winter impacts your business.

Julian Wood is Perkins Product Manager for Aftermarket.

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