5 Main Parts of a Car Engine (and their Functions)

Vehicle movement is the result of a combination of two processes occurring in the internal combustion engine: ignition and combustion of fuel occur in the engine itself. The engine then converts part of the energy generated by combustion into heat and mechanical torque. In order to achieve this, the engine is composed of several independent components (all essential) that work simultaneously. In this section, we will discuss the five most relevant main components of an automobile engine and find out their functions.

Engine Block

The first is the engine block. The engine block refers to a cylindrical metal part that guides the piston to perform linear reciprocating motion in the cylinder. The engine block is the pillar of the automobile engine, usually made of aluminum or iron. It accommodates almost all core components of the engine, such as piston, crankshaft and connecting rod, and is divided into three fixed components: cylinder head, cylinder block and crankcase. Its hole contains cylinders, and the engine can contain 4-16 cylinders, depending on the size. Most vehicles on the road today have four, six or eight cylinders. The engine displacement is determined according to the cylinder diameter. The air is expanded in the engine cylinder to convert thermal energy into mechanical energy, and the gas is compressed by the piston in the compressor cylinder to increase the pressure, thereby causing fuel combustion and piston reciprocating motion. Other holes in the engine are coolant and oil flow paths that are urgently needed for cooling and lubrication.


The second important component is the piston. The piston is the “heart” of the truck engine, which bears alternating mechanical and thermal loads. It is one of the key parts in the engine with the worst working conditions. The piston is generally cylindrical. According to the working conditions and requirements of different engines, the piston itself has various structures. Generally, the piston is divided into three parts: head, skirt and piston pin seat. The rotational force generated on the wheel begins with the movement of the piston. The piston is responsible for transferring the energy generated in the combustion cycle and transferring it to the crankshaft, thus driving our truck. The piston achieves this by moving up and down in the cylinder, driven by heat and expansion gas. The piston contains piston rings to ensure proper sealing and oil control. The pistons on many modern trucks are also coated with anti-friction materials, so the service life of the pistons is longer. These pistons move up and down in the cylinder twice per revolution of the crankshaft. This means that the engine speed is 2500 rpm and the piston moves up and down 5000 times per minute.


The third important component is the crankshaft. It receives the force transmitted from the connecting rod and converts it into torque to output through the crankshaft and drive other accessories on the engine to work. The crankshaft moves in the lower part of the engine block and in the journal. The crankshaft is subjected to the combined action of the centrifugal force of the rotating mass, the periodically changing gas inertia force and the reciprocating inertia force, so that the crankshaft bears the bending torsional load. Therefore, the crankshaft is required to have sufficient strength and rigidity, and the journal surface needs to be wear-resistant, uniform and balanced. The crankshaft is connected with the piston through the connecting rod, which undertakes the up and down motion of the piston and converts it into rotary motion or reciprocating motion. It rotates at the engine speed. Because of the hole, the crankshaft will not lose balance when rotating at high speed.


The fourth important component is the camshaft. The camshaft is the main body of the engine. Depending on the engine style, the camshaft can be located in the cylinder block or cylinder head. When the camshaft is located in the engine block, it is called the cam in the cylinder block engine. However, the camshaft of most modern engines is located in the cylinder head. Its main function is to adjust the opening and closing timing of the valve by pressing the end of the valve stem, that is, to obtain the rotational motion of the engine and convert it into up and down motion. This up and down movement controls the movement of the elevator, which in turn moves the push rod, rocker arm and valve. The camshaft is supported by a series of bearings that are lubricated in oil to ensure long engine life. Without the camshaft, it is impossible to start the engine. On the other side, the camshaft absorbs the rotational motion of the crankshaft and transmits it back to the linear motion.

Cylinder Head

The last important component of the engine is the cylinder head. Although the above components can be considered as an important part of the automobile engine, the cylinder head is much more accurate than them. The cylinder head contains many items, including valve springs, valves, lifters, push rods, rocker’s arms and so on. The cylinder head also controls a passage that allows intake air to flow into the cylinder during the intake stroke and an exhaust passage that allows exhaust gas to be removed during the exhaust stroke. The cylinder head is connected to the engine by so-called cylinder head bolts, and the sealed area between the two is sealed with cylinder head gaskets. Head gaskets can be a common source of engine problems.

The above components are the main components of the truck engine. The truck engine also contains many other components to hold everything together. Although modern truck engines seem daunting, I hope you can learn more about all these components to better understand your truck.