What You Need To Know About Diesel Engines?

Many motorists who have already opted for vehicles equipped with Diesel engines are well informed about their advantages and distinctive features. On the other hand, anyone dealing with this type of engine for the first time may have many doubts. In this article, we will try to answer some of these questions.

Diesel engine

The history of the diesel engine begins in 1824, the year in which the French physicist and mathematician Sadi Carnot put forward the theory that for the most efficient operation of a heat engine it is necessary to heat the working medium up to the combustion temperature of the fuel by means of quick compression. Later, this principle became the basis of the first diesel engine.

Over the years, numerous scientists, including Herbert Akroyd-Stuart and Gustav Trinkler, have been involved in the design of diesel engines. However, it was Rudolf Diesel in 1887 who created the first practical and efficient prototype.

Initially, the inventor believed that the best fuel for his engine was coal dust. However, due to its abrasive characteristics and difficulties in feeding the trolls, the decision was made to abandon this material. On the other hand, the Diesel prototype proved to be very efficient when fed with vegetable oil and light petroleum products.

Thereafter, diesel engines were constantly perfected. Nowadays, these powerful, economical, and reliable devices are installed in numerous passenger cars and most commercial vehicles.

Principle of operation

Currently, four-stroke engines are used in most passenger cars. Their operating cycle includes four phases:

  • Suction phase. It corresponds to the rotation of the crankshaft from 0 to 180 °. In this phase, the air enters the cylinder via an open valve.
  • Compression stage. During this phase, the crankshaft rotates from 180 to 360 °. Under the influence of the piston, the air already present in the chamber is compressed 16-25 times and its temperature rises to 700–900 ° C.
  • Combustion phase. In this phase, which corresponds to the rotation cycle 360–540 °, the injection and combustion of the fuel take place. Substances resulting from this process move the piston down.
  • Discharge phase. During the rotation of the crankshaft up to 540–720 ° from the initial position, the piston moves upwards and the flue gas is released.

In diesel engines, fuel is transported through a fuel pump. In modern cars, different types of fuel pumps are used:

  • On line. These pumps have the same number of retention pairs as they have cylinders in the engine. The retainer moves under the influence of the camshaft connected to the crankshaft, opening and closing the inlet and outlet holes. As a result, pressure is created which opens the pressure valve and fuel enters the respective injector. These pumps are very reliable, but they are mainly installed in the means of transport of goods. In passenger cars, they have not been used since 2000.
  • Their structure includes one or two check valves that perform a rotary and reciprocating movement, distributing the fuel between all the cylinders. This ensures a more even distribution of the fuel but accelerates the wear of the components involved. For this reason, metering pumps are mainly used with passenger cars.
  • High pressure. These pumps are used in Common Rail fuel systems and have the function of transporting the fuel in the supply channel, inside which high pressure is constantly maintained, regardless of the engine operating speed. The use of this system allows to increase the engine torque at low revs by 25% and reduce fuel consumption by 20%.
  • Injection pump. Each cylinder corresponds to a single injection pump, which simultaneously performs two functions: compression and injection. The use of this system makes it possible to increase fuel efficiency and reduce the toxicity of the flue gases since the injection process itself comprises three stages. Pre-injection ensures smooth combustion of the fuel-air mixture, while post-injection contributes to the regeneration of the particulate filter.

5 key benefits of diesel engines

They consume much less fuel than gasoline engines (on average, 30%). This is due to the presence of high pressure inside the combustion chambers, the structure of the engine, its principle of operation and a number of other factors. In addition, in most countries, diesel is cheaper than petrol.

In diesel engines, fuel is subject to combustion as it is transported, ensuring high torque at low rpm. This contributes to the improvement of the dynamic and traction characteristics of the vehicle.

They offer a high return, sometimes as much as 50%. Thanks to the glow plugs and heated injectors, diesel engines start smoothly regardless of the ambient temperature. They have a service life almost twice as long as gasoline engines.

9 rules for efficient use of diesel engines:

Follow these simple rules in order to reduce engine and fuel system repair time:

  1. Replace the fuel filter and filter drier promptly. Diesel engine components are very sensitive to water and mechanical particles. Due to their complex structure, injectors and pump components tend to get dirty very quickly. In addition, the sulfur present in the fuel, upon coming into contact with water, is converted into sulfuric acid, which has a destructive influence on the engine unit components.
  2. Pay attention to the quality of the fuel. The high sulfur content in low-quality fuel significantly reduces the efficiency and service life of engine oil and can lead to the deterioration of the particulate filter.
  3. Avoid driving at high speeds. It increases the loads on the engine.
  4. When choosing fuel, always take the ambient temperature into consideration. Diesel fuel contains paraffin, a substance that tends to freeze at low temperatures. Therefore, during the cold season it is recommended to use diesel in winter (suitable for use with temperatures between -25 ° C and 0 ° C) or arctic, which maintains its viscosity at temperatures between -35 ° C and 0 ° C. Normally, the temperature range suitable for the use of the fuel is indicated at the filling stations.
  5. Choose your diesel additives carefully. If the car is driven in cold climates, compounds that prevent freezing and thickening of the fuel should be used. In addition, there are additives that allow you to increase the engine torque and power by making the combustion of the fuel-air mixture more efficient, as well as solutions for cleaning the engine and fuel lines.
  6. Alternate urban travel with extra-urban travel in order to increase the engine rpm values ​​up to 2,500. In this driving mode, the soot and carbon deposits that have previously formed tend to burn, which considerably reduces the risk of coking of the injectors, sticking of the piston rings and failure of the catalyst.
  7. An engine equipped with a turbocharger will not stop immediately after stopping the vehicle. It is important to let it idle for another 2-5 minutes.
  8. Buy only the engine oil recommended by the vehicle manufacturer and never mix lubricants that have different degrees of viscosity.
  9. It accelerates smoothly to avoid the destruction of the sliding bearings in the turbine.


Modern diesel engines are economical and powerful. Despite the stereotypes, they work quietly and are environmentally friendly. Cars equipped with Diesel engines are perfectly suited for suburban trips, convenient for large groups and families, reliable even with constant loads. In addition, they are very reliable in off-road conditions, which is why they enjoy great popularity among lovers of fishing, hunting and other outdoor activities.

However, if you are a sports car lover and you have a driving style characterized by sharp acceleration and braking, a diesel car will hardly be for you. An aggressive driving style could prove fatal to the engine.

Repairing a diesel engine is expensive. However, if you follow the advice above, this will rarely happen.