How to Start a Diesel Truck in Winter: What You Should Know

As the weather gradually turns colder and the temperature drops day by day, we are about to welcome the coldest winter of the year. During this season, when truck drivers are driving outside, they often encounter a headache-inducing problem – difficulty in starting the truck. This is mainly because diesel engines mainly rely on the heat generated by a high compression ratio to ignite fuel. When the temperature drops sharply, the low temperature can cause the engine oil to thicken, the battery performance to decline, and diesel to solidify, making it more difficult to start the truck in winter.

This not only affects the driver’s driving plan but may also cause potential damage to the vehicle. So, in the face of this common malfunction phenomenon, how should we deal with it? Next, we will explore together effective ways to solve this problem.

Why Diesel Trucks Are Hard to Start in Winter

The operation mode of diesel engines is different from that of gasoline engines. The winter environment will have the following impacts on them:

Low Ambient Temperatures Reduce Combustion Heat

Diesel requires a high compression temperature to ignite. In winter, the cold metal engine block absorbs heat during startup, causing the combustion chamber to fail to reach the temperature required for ignition. This is one of the main reasons why diesel engines are difficult to start in sub-zero temperature environments.

Engine Oil Thickens

Low temperatures will thicken the engine oil and increase the internal resistance of the engine. Starting the motor requires more effort to turn the engine. If the engine oil is too thick, the starting speed will be too low and ignition will not be possible.

Diesel Fuel Gels in Low Temperatures

Diesel contains paraffin wax, which solidifies at low temperatures. After solidification, the fuel filter may get clogged and the fuel flow will be restricted. If no appropriate additives are added or winter-specific diesel is used, the condensation phenomenon will cause a complete failure of cold start.

Batteries Lose Power in the Cold

The starting power required by diesel engines is much higher than that of gasoline engines. Below freezing point, battery capacity will decline. A battery with insufficient power may not be able to provide enough current to quickly start the engine.

Glow Plug or Grid Heater Performance Declines

The preheating system – the preheating plug in light diesel engines and the preheating plate in many Cummins engines – is used to heat the intake or combustion chamber to assist in starting. If these components wear out or their circuits malfunction, cold starting will become extremely difficult.

Diesel engines operate differently than gasoline engines, and winter conditions affect them in several ways:

Step-by-Step: How to Start a Diesel Truck in Winter

Following these steps can increase the chances of a successful start, even in extremely cold weather:

1. Allow the Glow Plugs or Grid Heater to Complete Preheating

Turn the key to “ON” and wait until the preheating plug indicator light goes off. In most heavy-duty trucks fitted with Cummins engines, the preheating plate will start heating the intake air on its own. In such instances, you may want to wait until preheating is complete to ensure that the engine gets enough initial heat.

2. Cycle the Preheat System Twice if Needed

Under very cold conditions below -10°C, double circulation of the preheating plug or the preheating plate can greatly optimize cold start performance.

3. Warm the Battery Before Cranking

You can switch on the headlights for 10 seconds to enable the battery and enhance its chemical reaction. If the power in the battery is not enough, then use the starting power supply or connect your truck to an external power source.

4. Use the Correct Winter Diesel Fuel

Using wing-specific diesel or adding antifreeze can prevent the wax in the fuel system from solidifying. This is one of the key steps that help ensure reliable operation in winter.

5. Use the Engine Block Heater

Most trucks have original cylinder block heater interfaces, especially Cummins diesel engines. If the cylinder block heater is connected for some hours, it will preheat the coolant and the engine block to greatly improve its cold start performance.

6. Crank the Engine Properly

Each of these startups should not take more than 10 seconds, with an interval of from 10 to 15 seconds between each startup. Continuous starting can cause the starter motor to overheat or deplete the electrical power in the battery.

7. Let the Engine Idle Before Driving

After starting, let the truck idle for a few minutes to improve lubrication and preheat the fuel system. Immediately driving under heavy load could be harmful to the engine.

Maintenance Tips to Prevent Hard Starts in Winter

Preventive maintenance is the best means of avoiding problems when trying to start in winter. Please pay close attention to the following aspects:

Use the Right Engine Oil

Low-viscosity engine oil should be used in winter. For example, many diesel trucks use 5W-40 synthetic engine oil. The right engine oil can ensure that the engine starts more smoothly and reduce engine wear. Using original factory-quality oil filters, such as Cummins brand filters, can keep the lubrication system clean.

Replace Fuel Filters Regularly

A blocked fuel filter will eventually lead to a serious power loss and poor cold starts. Diesel oil is more viscous at low winter temperatures, so this filter needs to be clean.

Maintain a Strong Battery

Check the condition of the battery before winter. Since diesel trucks require high CCA (cold start current), replacing aged batteries before the temperature drops can avoid unexpected malfunctions.

Inspect Glow Plugs or Grid Heaters

These components determine whether your diesel vehicle can start at freezing point temperatures. If you drive a truck with a Cummins engine, take the time to ensure the preheating plug, relay, and wiring harness are operating as they should.

Keep the Air Intake and Fuel System Clean

Regular maintenance of sensors, fuel injectors and intake components will keep the engine in good operating condition, even at very low temperatures.

When to Consider Upgrading Your Engine or Components

If your diesel truck still has a hard time starting in winter, after you have it properly maintained, it may be time to consider upgrading some components, or even replacing the entire engine.

As time progresses, older diesel engines will begin lowering their compression ratio, which in effect reduces their capability to build the initial heat they need to start their cold engine. Moving to newer technologies, such as a modern high-pressure common rail fuel system, can enhance performance in low-temperature environments significantly.

In this respect, Cummins diesel engines are doing a great job. Cummins engines enjoy a reputation for being solid, boasting advanced fuel injection systems and efficient preheating systems. These features inherently place trucks with Cummins engines in a favorable position during cold startups. Its rigid and durable design enables it to maintain stable performance in extreme winter environments and makes it suitable both for mining trucks and for fleets that are commercially used in northern climate regions.

If your truck has difficulty starting every winter, please consider replacing the following parts:

• Preheating plug or preheating element
• Fuel injector
• High-pressure oil pump
• Starting motor
• Engine control sensor

Or, for severely worn engines:

• Upgrading to a refurbished or replaced Cummins diesel engine can restore reliability, improve fuel efficiency, and significantly enhance cold start performance.

Keeping Your Diesel Ready for the Cold

In the cold winter, truck drivers may encounter the problem of difficulty in starting their vehicles, which is undoubtedly one of the situations they are most worried about. However, as long as the correct methods are mastered and proper maintenance is carried out, most cold start problems can be avoided.

Therefore, when a vehicle fails to start, we need not be overly anxious. By making adequate preparations and maintenance, we can ensure that the diesel system operates smoothly, efficiently and without faults even in the coldest weather.