Do you drive a Cummins, Duramax, or Ford Power Stroke diesel truck? If so, then you have probably already discovered that not all mechanics can work on diesel engines. Sure, they may be able to handle non-engine repairs and maintenance. However, they may lack the training and expertise to handle your diesel engine.
You may not know why there is a difference. In this blog, we will break down the differences between gas and diesel-powered engines. Our goal is to help you understand Why You Need a Diesel Mechanic to take care of your truck.
How Engines Work
Both gas and diesel engines work by converting fuel into energy. They use combustion for the conversion. Combustion is a fancy name for repeated small explosions. These explosions occur in your engine as it converts fuel to move your vehicle. Therefore, they are both types of internal combustion engines (ICE). The difference is that gas engines require a spark, while diesel engines use compression.
Gas-powered engines have a lower flashpoint but a higher volatility point than diesel engines. The fuel mixes with fresh air, compressing the air. Then, a spark ignites the fuel, providing the engine’s power.
Diesel engines do not require a spark. Instead, the air and fuel are squeezed or compressed and explode on their own. That is why diesel engines are also called compression engines. Why You Need a Diesel Mechanic? Because we know how engines work.
Are All Engines ICE?
Not automobiles have historically been ICE vehicles. However, until recently, all engines on automobiles available in the United States were some ICE variation. Today, there is more variety because of hybrids, electric vehicles (EVs), and plug-in hybrid electric vehicles (PHEVs). Despite these changes, most vehicles are still ICE vehicles.
The Four Stroke Combustion Cycle
For passenger vehicles, the most common engine combustion cycle is the four-stroke combustion cycle. The four strokes are the intake stroke, the compression stroke, the power stroke, and the exhaust stroke.
The stroke refers to the path the piston takes. The piston starts at the top dead center (TDC) and travels to the bottom dead center (BDC). That creates a vacuum inside the cylinder, which draws in fresh air. On the return from BDC to TDC, the piston compresses that air (which may also have fuel present). The compression causes combustion. The combustion moves the piston back from TDC to BDC. Moving from TDC to BDC turns the engine’s crankshaft. Finally, the piston returns from BDC to TDC, pushing exhaust gasses out of the cylinder.
The significant differences in diesel and gas engines occur in the compression stroke. Gas engines utilize sparks to ignite a fuel/air mixture. Diesel engines rely on compression alone.
Liters and Engine Sizes
You have heard the term liters used to measure engines. The number of liters measures the volume of the cylinders. Each liter is 1,000 cubic centimeters, rounded up to a tenth of a liter.
More liters usually mean a more powerful engine. Engine size refers to engine capacity or displacement.
In a gas engine, a standard 6 cylinders might be 2.5 to 2.5 liters. For larger diesel trucks like the Ford Power Stroke, the engine might be 8 cylinders with a 6-to-7-liter capacity.
You cannot directly compare engine size or capacity between diesel engines and gas-powered engines. The better fuel economy in a diesel-powered engine prevents that comparison. Diesel engines are more powerful than comparably sized gas-powered engines.
If you want to compare the engine capabilities across fuel types, you need more information. Look at things like horsepower (HP), torque, and towing capabilities.
Diesel Engines are More Efficient
Why do people choose to drive diesel vehicles? Fuel efficiency is one reason. Diesel engines have about 20% greater fuel economy than gas-powered engines.
Their efficiency is due to many things. There is more energy in diesel fuel than in the same amount of gas. Diesel engines also have a high internal heat efficiency.
Even the best-designed gas-only engines cannot meet a diesel-powered engine’s efficiency. However, gas hybrid engines or PHEVs can approach, and in some circumstances even surpass, the fuel economy of a diesel engine. This is why you need a diesel mechanic?
Diesel Engines are More Powerful and Offer More Torque
People think fuel-efficient engines mean less power. However, diesel engines can offer more power and torque at lower RPMs.
Torque has a generic meaning in physics. When talking about cars, torque refers specifically to the force created by an engine’s crankshaft.
The more torque, the more work the vehicle can do. The power is available for towing and for acceleration. Torque is what makes diesel engines perfect for towing, whether towing for commercial applications or recreational ones.
Diesel Engines and Horsepower
Another measurement that people often hear applied to engines is horsepower. Horsepower as a term of measurement came about because of an early comparison to draft horses. However, you do not need to know how powerful a horse is to understand HP.
One HP is the power required to move 550 pounds the distance of one foot in one second. Horsepower is a rough approximation of a vehicle’s speed. However, a diesel engine may be lower HP and still offer more immediate acceleration. This initial acceleration is the result of how a compression engine converts fuel to energy.
Diesel Engines are More Reliable
Reliability is one of the big reasons that diesel engines remain popular for commercial use. Diesel engines are considered more reliable than gas-powered engines.
They operate at lower RPMs than gas-powered engines. Lower RPMs mean less wear and tear on the engine, which means a longer life. Gas-powered engines may start to be questionable around 125,000 miles, depending on the model. Well-maintained diesel engines can handle 200,000 to 300,000 miles without any significant issues.
Diesel engine construction also increases their lifespan. Diesel engines have thicker cylinder walls, thicker castings, and higher-capacity oil systems. All of this leads to less chance of a major engine failure.
Diesel engine design means they are easy to repair. Constructed with a replaceable lining, mechanics can fix diesel engines without rebuilding them.
Downsides to Diesel
While diesel engines are more fuel-efficient and more powerful than gas-powered engines, they have a few downsides. As a result, auto manufacturers have limited their production of diesel-powered vehicles, at least for the U.S. market.
Diesel vehicles were once worse for the environment than gas-powered vehicles. Changes in engineering have corrected that issue. However, these exhaust gas recirculation (EGR) systems have created new challenges. EGR systems can be challenging to maintain, diagnose, and service.
Diesel trucks may be louder than gas-powered trucks. Engineering changes have also helped with noise pollution concerns.
Diesel fuel is usually more expensive than gas. However, for long-distance driving, diesel vehicles’ fuel efficiency eliminates these cost differences. This is why you need a mechanic to tell you the good and the bad.
Maintenance for Your Diesel Vehicle
Engine maintenance requirements are becoming more forgiving. Your vehicle comes with a recommended maintenance schedule. Recommended maintenance is appropriate under usual driving conditions. If you drive outside of those conditions, you may need more frequent maintenance.
Regular maintenance includes:
- Oil and oil filter changes;
- Monitoring gaskets for leaks;
- Ensuring you always have proper coolant levels and no leaks in your coolant systems;
- Changing your air filter;
- Changing your fuel filter; and
- Regularly inspecting your glow plugs.
Specialized Care from Specialized Truck and Auto
Hopefully, you now understand a little more about the differences between your diesel engine and a gas-powered engine. These differences are why diesel engines need experienced diesel mechanics. Our hope is that we become your mechanic of choice.
Good mechanics will give you an honest opinion if you are contemplating purchasing a new or used diesel vehicle. They can provide you with the maintenance you need to keep your vehicle in top shape. Also, they are there when you need affordable, reliable, and speedy repairs.