Diesel engines were revolutionary when first introduced around the turn of the 20th century. They were so much more efficient than steam-powered engines. Today, the diesel engine is the top source of power for the commercial trucking industry. Over its years of evolution, proper diesel maintenance is has remained essential to keep the engine working in top form. 

How does a diesel engine work?

Rudolf Diesel developed the diesel engine prototype in 1893, and the first engine in production in 1897. Credit also goes to Swiss engineer Alfred Büchi. In 1925 Büchi turbocharged the engine to improve its efficiency substantially, creating the modern diesel engine. German engineer Robert Bosch’s 1927 improvements to the fuel injection pumps helped too. However, as the engine developed, the answer to “how does a diesel engine work?” has remained the same.

A diesel engine is an internal combustion engine that takes air, compresses it, and then injects fuel into the compressed air. The heat of the compressed air ignites the fuel without the need of a spark plug, as in a gasoline engine. 

The combustion cycle is a four-step process that repeats:

  1. The piston moves down to take in air.
  2. The piston moves up to compress the air in the fuel cylinder. Before it reaches top-dead-center, diesel fuel is injected into the cylinder for combustion.
  3. The piston draws down again, with intake and exhaust valves closed.
  4. The piston forces the combusted fuel out of the cylinder as exhaust.

Since the diesel engine only compresses air, its compression ratio is much higher than gasoline engines, which leads to better efficiency. As the Department of Energy further notes, “Unlike the emission control systems on gasoline vehicles, many diesel vehicles have additional after-treatment components that reduce particulate matter and break down dangerous nitrogen oxide (NOx) emissions into harmless nitrogen and water.”

How long does a diesel engine last?

Does a diesel engine last longer? That depends on several factors, but it’s estimated that a diesel engine can run continuously for 1,000,000-1,500,000 miles before it needs major work. That means a well-maintained diesel engine might be on the road for 30 years or more.

Does a diesel engine last longer than a gasoline engine?

For comparison, a car’s gasoline engine might last for around 200,000 miles before it needs serious work or replacement. That’s substantially less than the diesel engine’s 1-1.5 million miles.

What makes the diesel engine more resilient? The longevity is due to:

  • The overall design of the engine
  • The fuel used
  • The vehicles using diesel engines that tend to be built with more heavy-duty components
  • The engine’s self-cooling ability

Tips to make your diesel engine last longer 

The spontaneous combustion diesel engine has a lot going for it in its design. Still, drivers and fleet managers can help make a diesel engine run longer. Top tips include:

  • Choosing the right fuel. Use the best quality you can afford and fill the tank instead of using just a few liters.
  • Allowing the engine to cool down after every trip. Putting it in neutral when you come to a final stop helps keep your turbochargers in top shape.
  • Maintaining a moderate revolutions per minute (RPM). Prevent damage to the engine and protect the gearbox from vibrations.
  • Keeping diesel filters properly cleaned.
  • Giving your vehicle more TLC in the winter months to help keep it in optimal condition.

Want to know more about preventive maintenance? Check out Motive’s guide on preventive maintenance.

Why is diesel engine maintenance important?

Avoiding unscheduled vehicle downtime is critical to the commercial fleet’s success and driver revenues. Especially in the midst of the supply chain crisis of the COVID-19 pandemic, proper diesel maintenance can make a big difference in navigating the uncertain environment.

An improperly maintained diesel engine will have a shorter lifespan and decreased fuel efficiency. Depending on the type of roads and weather conditions, the engine’s parts may also wear down more quickly, which means more downtime for that vehicle. 

Diesel maintenance is also critical to road safety. A vehicle operating in unsafe conditions is a hazard to your driver, your cargo, and your business. With a fleet safety solution, drivers and fleet risk managers can better prevent undesired incidents such as collisions and breakdowns.

Common diesel engine problems

Failure to keep up with routine servicing. Neglecting oil and filter changes and fluid analysis doesn’t help you take care of your engine.

Overheating. Diesel engines run hotter than gas motors, which means the radiator is subject to higher temperatures. Proper cooling system maintenance is important. Don’t neglect your coolant as it will turn acidic over time, which has a negative effect on the engine.

Filthy filters. If you aren’t replacing the diesel filter regularly, it can “choke” your engine. This forces the engine to use more fuel to get power and acceleration, and wears the engine down. You’ll know to check your filter when you notice weak acceleration or decreased engine power.

If you have an older diesel engine, be sure to empty the water separator to avoid leaks or moisture residue that can damage the engine. You’ll also want to let the engine reach the proper operating temperature to get efficiency. 

With new diesel engines, don’t forgo oil additives. Since these engines create a lot of heat and water residue, it can help to enhance engine lubrication with fuel additives. In winter, you’ll want to use winterization additives to prevent fuel clogs and reduced efficiency.

Diesel engine maintenance checklist

Stay on top of diesel engine maintenance with this simple-to-follow checklist.

  • Change oil and filters regularly.
  • Check and preserve water control components.
  • Keep water out of the fuel tank.
  • Maintain fuel injectors.
  • Check the alternator, radiator, compressor, and condenser mountings for looseness or cracks.
  • Check vibration damper for cracks, bulges, shifting, or damage.
  • Watch out for unusual sounds and basic warning signs that indicate the need for repairs, such as fuel contamination, oil oxidation, or a black exhaust problem.

Learn about California’s smog check rules for fleet vehicles.

Keep on top of your diesel engine maintenance schedule with Motive

Knowing how to maintain a diesel engine is only part of keeping them running as smoothly as possible. Keeping up with a diesel engine maintenance schedule can help ensure your vehicle operates efficiently and cleanly.

Motive’s complete maintenance solution makes it easier for you to uphold proper diesel engine maintenance.

  • Vehicle inspections are customizable to each type of vehicle, helping drivers easily track defects. 
  • Vehicle diagnostics allow managers to identify and resolve issues before they compromise other parts or result in a breakdown.
  • Maintenance reminders automatically track upcoming vehicle service needs to help ensure vehicles stay healthy and generate revenue. They’re also available to customers with Pro and Enterprise plans. 

Motive’s platform offers drivers and fleet managers an even deeper look into equipment health. This allows both to recognize problem areas before they affect daily operations and take a proactive stance on road safety too. Learn more today.