Frequently asked questions about diesel engines

The lifespan of an average diesel engine is anywhere from 400,000 miles to 1,000,000 miles, while the average lifespan of a gas engine is around 200,000 miles.

Diesel engines are designed differently from petrol engines, meaning they have more room within the engine for more oil to move freely. This allows the components of the engine to run longer at optimal levels.

Other key factors in the durability of diesel engines are their overall design, and their application uses compared to other engines.

The most accurate method of diagnosing engine problems is to contact the engine manufacturer to get their insight on solutions. Beyond that, here are a few common diesel engine problems.

• Black Smoke: A common feature of the old locomotive engines, black smoke is a clear sign of a serious problem with your diesel engine. There are several causes for black smoke, like a faulty injector pump, a bad EGR valve, or something as simple as low operating temperatures. Cleaning out the air system is an excellent first step to combat this, but ultimately you should consult with a specialist.
• Hard Starts: Colder conditions can commonly lead to hard starts for diesel engines. The weather is only a catalyst that leads to the issue of hard starting the engine. A hard start or no start can be caused by faulty glow plugs, defective battery, or a problem with the fuel system, to name a few.
• Contaminated Fuel: Due to its higher viscosity, diesel fuel has a higher chance of becoming contaminated. Water, soot, and other debris are common fuel contaminants. Refueling is a simple fix, but if you cannot catch this problem early enough, you will need to bring the engine to a professional to be fixed.

These diesel engine problems and solutions are difficult to manage on your own. Any time you can identify a serious issue with the engine, it is advised to take it to a specialist or contact the manufacturer. Engines can be fixed, but only correctly by professionals. For industry trusted professionals, consider taking all your diesel engine troubles to Cummins. Our engines and service are best in class.

Depending on the performance of the engine, how often it needs to be serviced will vary. A safe practice would be to have a diesel engine serviced every six months. At the very least, it should be looked at once a year to make sure everything is in working order. This is not a concrete rule, as the type of diesel engine and what it is used for will have a significant impact on how often it will need to be serviced. Cummins’ service manual is a great resource that provides maintenance schedules based on product type.

One other key aspect for servicing a diesel engine is variation. A long-haul truck operating daily over several hundred miles would have distinct service and maintenance requirements compared to a personal car with a diesel engine that only needs servicing every six months.

Another example of this variation would be for mining trucks. They haul amazon loads almost all day long for weeks and months in very direct environments. Their maintenance and service needs therefore are different from that of a long-haul truck or every day commercial car.

Cummins is one of the world’s leading manufacturers of diesel engines. In 2018, Cummins supplied the most Class 8 diesel engines. There were 309,701 diesel engines used in Class 8 trucks that year, and Cummins was responsible for 38.3% of them.

Diesel engine types are most commonly designated by size. There are three types:

• Small: Small diesel engines are classified as outputting at most, 288 horsepower. These are also either direct injection, in-line, four- or six-cylinder engines. Due to their relative size and power, they are most commonly found on smaller trucks or automobiles. Of the three types, this is the most common diesel engine produced.
• Medium: Medium diesel engines are a step up from small ones. They can produce up to 1,000 horsepower. Some V-8 and V-12 engines belong to this group. This engine type is commonly used in heavy-duty trucks.
• Large: At this level, we are discussing serious power. Large diesel engines are used to power trains, ships, and other large vehicles or equipment. They operate at an excess of 1,000 horsepower.

Diesel engines are made up of dozens of parts. However, the engine parts list below provides information about nine of the most vital components.

• Block: As the foundation of the modern diesel engine, the block is where all the parts for the basic internal combustion process are contained. The block has an open space for each cylinder, where the combustion happens.
• Pistons: The pistons create the bottom of the combustion chamber, moving up and down in the cylinder while the engine is working. The movement of the pistons creates the compression of the air that leads to combustion.
• Cylinder Head: The cylinder head closes the top of the open space in the block to reach the chamber where combustion happens. This head can be one unit to cover all the cylinders or multiple units that cover a section.
• Valves: With the cylinder closed by the piston at the bottom and the cylinder head at the top, there needs to be a way to allow fresh air in and the leftover gasses out. This is where the valves come in. There are usually two valves for taking in air and two for the exhaust for each cylinder.
• Fuel Injectors: Now, there needs to be a way to get fuel inside the cylinder, so there is something to combust. These components are a complex part of the process, spraying fuel in very precise patterns with highly controlled timing.
• Camshaft: Rather than relying on an electrical system for opening valves and fuel injection, most engines use a mechanical process. The camshaft’s revolutions control the timing of these events by lobes on the shaft that set them into motion.
• Connecting Rods: These pieces connect to a piston at the bottom arm and carry the force of the combustion to the crankshaft.
• Crankshaft: The crankshaft transfers the linear motion of combustion (the up-and-down part of the combustion process) into a rotational motion.

Learn more about the components of a diesel engine.

In diesel engines, internal combustion results in expansion of high-temperature, high-pressure gases, which in turn move pistons, transforming chemical energy into mechanical energy. Learn more about how a diesel engine works.

The modern diesel engine starts with a block containing all the parts for the basic internal combustion process, with an open space for each cylinder where combustion takes place. Learn more about how a diesel engine works.

The engine must continuously deliver air, fuel, and lubrication to the cylinders. Engine emissions created as by-products of combustion must also be treated to meet global environmental standards, covering air, fuel, lubrication, cooling, and filtration systems. Learn more about how a diesel engine works.

Oxygen density changes depending on air temperature and altitude, making surrounding air non-ideal. To address this, Cummins introduced the first turbochargers in the 1950s. Learn more about how a diesel engine works.

While diesel engines are known to pollute by emitting fumes and soot during use, they are cleaner than you may think. A positive by-product of the Environmental Protection Agency (EPA) regulations is that diesel engines are cleaner than they have ever been. Due to healthier and more efficient engines being manufactured, they could last 30 years or more.

While no internal combustion engine (ICE) is operating 100% clean, the concept of clean diesel has been in the works at companies like Cummins for some time. Biodiesel is just one way in which we strive to create cleaner alternatives.

Cummins, in common with all other engine manufacturers, only certifies engines to meet the prescribed EPA (or other local regulatory agency) registered fuels.

Two advantages diesel engines provide is that they are more durable and reliable than petrol engines. They do not require spark plugs to ignite fuel. Diesel engines also have better fuel economy than petrol engines.

With that being said, diesel engines are used in vehicles, machines, and other projects where petrol engines simply would not be able to perform the tasks.

Diesel engines can last for more than 30 years which means these engines will be working longer and harder than its counterparts.

The advantages and disadvantages of petrol and diesel will more or less come down to the needs of the individual or organization's practical use. For large-scale operations, having large diesel engines at your disposal is necessary in most cases. In either case, working with a manufacturer like Cummins will ensure that you receive the best engine for your needs.

While diesel engines are the preferred option under specific circumstances, there are still some drawbacks to using them. For one, diesel engines, on average, cost more to fuel than petrol engines.

Another disadvantage of using diesel engines that most people associate with them is its environmental impact. Cummins is constantly at work with new initiatives to create a cleaner future for diesel engines.

Yes. Renewable diesel is suitable for use in diesel engines (please always check with your OEM and vehicle manual before trying a new fuel). We announced compatibility with select renewable diesel fuels for our B6.7 and L9 engines. This type of fuel is an excellent move in the right direction to combat the disadvantages associated with using diesel.

Diesel engines are classified by size:

• Small: Up to 288 hp, found in small trucks or automobiles
• Medium: Up to 1,000 hp, used in heavy-duty trucks
• Large: Over 1,000 hp, used for trains, ships, and other large vehicles

They can also be classified by combustion cycle:

• Four-stroke
• Two-stroke

Learn more about what makes diesel engines advanced diesel engines.

Four-stroke engines have four stages: intake, compression, power, and exhaust. Two-stroke engines combine these into two strokes. Two-stroke engines were phased out due to high pollution and frequent breakdowns, leaving four-stroke engines as the superior type. Learn more about what makes diesel engines advanced diesel engines.

Key advancements include improved fuel efficiency with fewer emissions, longer oil-drain intervals, and maintenance-free filters. In one study, diesel vehicles show 24% greater fuel efficiency in city driving and 29% on the highway. Learn more about what makes diesel engines advanced diesel engines.

Diesel engine pistons rise all the way to the top of the cylinder, creating a higher compression ratio than gasoline engines. This delivers air faster at quicker combustion rates, resulting in increased torque, horsepower, and overall efficiency. Learn more about what makes diesel engines advanced diesel engines.

Today's clean diesel engines emit 90% less harmful emissions than engines produced before the year 2000. Cummins produces engines capable of removing as much as 98% of particulate matter from exhaust. Learn more about what makes diesel engines advanced diesel engines.

Rudolf Diesel, a German inventor and mechanical engineer, patented the first compression ignition engine design in 1892 and successfully created the first diesel engine prototype in 1897. Learn more about the history of diesel engines.

One of the first fuels Rudolf Diesel considered was vegetable seed oil, which eventually led to the creation of biodiesel. Today, diesel fuel is created by refining crude oil and other biomass materials. Learn more about the history of diesel engines.

There are three common types:

• Diesel #1: Lower viscosity, better in cold temperatures, and burns faster
• Diesel #2: Thicker, less expensive, and more fuel efficient
• Biodiesel: Made from plant oils and/or animal fats

Learn more about the history of diesel engines.

Diesel engines used today are classified by size:

• Small: Light trucks, agriculture, and construction
• Medium: Heavy-duty commercial trucks
• Large: Trains, ships, and large generators

Learn more about the history of diesel engines.

Diesel engines power delivery trucks, trains, buses, boats, construction machinery, and military vehicles, and also run generators that provide electricity to remote locations and emergency power for large facilities like hospitals. Learn more about the history of diesel engines.

Clessie Cummins founded Cummins Engine Co. in Columbus, Indiana in 1919, in partnership with William G. Irwin. Learn more about the history of diesel engines.

Cummins is focused on increasing waste-heat recovery, reducing engine friction, offering a broad portfolio of power solutions, and supporting the use of biodiesel including B20 while continuing to look toward B50 and B100 diesel. Learn more about the history of diesel engines.

Cummins offers six current diesel engines:

• X15 Efficiency Series (400–500 hp)
• X15 Productivity Series (430–605 hp)
• X15 Performance Series (525–565 hp)
• X12 (350–525 hp)
• L9 (260–380 hp)
• B6.7 (200–325 hp)

Learn more about Cummins diesel engines.

Cummins diesel engines offer solutions for a wide variety of medium-duty and heavy-duty truck markets. Learn more about Cummins diesel engines.

Diesel allows you to go farther with less while delivering better acceleration, towing, and hauling potential when compared to gasoline counterparts. Learn more about Cummins diesel engines.

Yes. When paired with innovative aftertreatment systems and cutting-edge engineering, diesel engines can operate with net zero emissions and supplement operations with biodiesel blends. Learn more about Cummins diesel engines.

The Next Generation X15 is the next step in Cummins' fuel-agnostic 15-liter platform, offering up to 605 hp and 2,050 lb-ft of torque, demonstrating Cummins' continued commitment to the evolution of internal combustion technology.

The Cummins X10 is a next generation engine that bridges the gap between medium-duty and heavy-duty applications, designed to provide efficiency and dependability.

Cummins’ approach to the future of diesel is focused on increasing waste-heat recovery, reducing engine friction, offering a broad portfolio of power solutions, and supporting the use of biodiesel including B20 while continuing to look toward B50 and B100 diesel. Learn more about the history of diesel engines.

“We are committed to advancing diesel technology while our markets and our customers need it to run their businesses”

José Samperio, Vice President and General Manager for Cummins On-Highway Business in North America

Cummins also already offers a fuel-agnostic 15-liter engine platform that includes advanced diesel, hydrogen, and natural gas engines. Learn more about Cummins diesel engines.