Basic Parts of an Engine – Engine Components

Car Engine Parts

A car engine is a complex mechanism, design with multiple internal parts that work like clockwork to create power that runs your vehicle. All parts must be in good condition for the engine to work properly.

Let’s discuss basic parts of an engine – Engine Components. The engine block houses the parts such as the crankshaft, camshaft, crankcase, spark plugs, cylinder heads, valves, and pistons.

The list of Engine Components

Let’s discuss them one by one :

1. Engine block

The engine block is the main part of an engine. Often made of aluminum or iron, it has several holes to contain the cylinders as well as provide water and oil flow paths to cool and lubricate the engine. Oil paths are narrower than water flow paths.

The engine block also houses the pistons, crankshaft, camshaft, and between four and twelve cylinders depending on the vehicle, in a line, also known as inline, flat, or in the shape of a V.

All other parts of the motor are essentially bolted to it. Inside the block is where the magic happens, such as combustion.

2. Piston

A piston is a moving disk enclosed in a cylinder that is made gas-tight by piston rings. The disk moves inside the cylinder as a liquid or gas inside the cylinder expands and contracts. A piston aids in the transformation of heat energy into mechanical work and vice versa.

Pistons move up and down as the spark plugs fire and the pistons compress the air/fuel mix.

This reciprocating energy is converted to rotary motion and transferred to the tires by the transmission, via the driveshaft, to make them spin.

Pistons on engines rotating at 1250 rpm move up and down 2500 times per minute. Inside the piston are piston rings, which are used to generate compression and reduce friction through constant rubbing of the cylinder.

3. Cylinder head

The cylinder head sits above the cylinders on top of the cylinder block. It closes at the top of the cylinder, forming the combustion chamber. This joint is sealed by a head gasket to prevent the loss of gases.

The cylinder head contains many elements, including valve springs, valves, lifters, pushrods, rocker arms, and camshafts to control passages that allow intake air to flow into the cylinders during the intake stroke, as well as exhaust passages that remove exhaust gases during the exhaust stroke. 

4. Crankshaft

The crankshaft is a moving part of the internal combustion engine. Its main function is to transform the linear motion of the piston into rotational motion. The pistons are connected to the crankshaft through the connecting rods. The crankshaft is mounted within the engine block.

The crankshaft is located at the bottom of the engine block, within the crankshaft journals (an area of the shaft that rests on the bearings). This keenly machined and balanced mechanism is connected to the pistons through the connecting rod.

The crankshaft turns the pistons up and down motion into a reciprocal motion, at engine speed and converts energy from reciprocating motion into rotation.

5. Camshaft

A camshaft is a rotating object usually made of metal that contains pointed cams, which convert rotational motion to reciprocal motion. Camshafts are used in an engine to operate the intake and exhaust valves, mechanically controlled ignition systems, and early electric motor speed controllers.

Camshafts in automobiles are made from steel or cast iron and are a key factor in determining the RPM range of an engine’s power band.

The camshaft can vary from vehicle to vehicle and is located either in the engine block or in the cylinder heads. Many modern vehicles have them in the cylinder heads, also known as Dual Overhead Camshaft (DOHC) or Single Overhead Camshaft (SOHC), and are carried by a series of bearings that are lubricated in oil for long life.

The function of the camshaft is to regulate the timing of opening and closing of valves and to transfer the rotary motion from the crankshaft to an up and down motion to control the movement of the lifters and to move the pushrods, rockers, and valves.

6. Timing Belt/Chain

A timing belt, timing chain, or cambelt is a part of an engine that synchronizes the rotation of the crankshaft and the camshaft so that the engine’s valves open and close at the proper times during each cylinder’s intake and exhaust strokes.

In an interference engine, the timing belt or chain is also critical to preventing the piston from striking the valves. A timing belt is usually a toothed belt, a drive belt with teeth on the inside surface. A timing chain is a roller chain.

The belt is made of heavy-duty rubber with gears to grip the pulleys from the camshaft and crankshaft. The chain, much like your bike chain, wraps around pulleys with teeth.

7. Engine Valves

Engine valves are mechanical components used in engines to regulate the air, fuel, and exhaust gas flow in the combustion chambers or cylinder head during engine operation.

The valve operation is very simple: the cam pushes the valves down into the cylinder against the spring, opening the valve so gases can flow, and then lets the valve shut under the force of the spring. The pressure in the combustion chamber rather neatly helps seal the valve shut.

8. Oil Pan

The oil pan is vital, though simple, part of your engine’s lubrication system. Oil circulates through parts of your engine to keep them lubricated. It reduces friction so everything works smoothly. Without oil, friction would quickly destroy your engine.

The oil pan keeps that oil contained in the lubrication system, so it’s important that the oil doesn’t leak out. Since it’s a metal part attached to another metal part, there is a gasket between the oil pan and the part of the engine it attaches to.

9. Combustion chamber

A Combustion Chamber is the area within the Cylinder where the fuel/air mix is ignited. As the piston compresses the fuel/air mix and makes contact with the Spark Plug, the mixture is combusted and pushed out of the Combustion Chamber in the form of energy.

The Cylinder houses many of the important components of an Internal Combustion Engine including the Injector Nozzle, Piston, Spark Plug, Combustion Chamber, and others.

10. Intake manifold

The intake manifold in a car is the part of the engine that distributes the air flow between the cylinders. Often an intake manifold holds the throttle valve (throttle body) and some other components.

In some V6 and V8 engines, an intake manifold can be made of several separate sections or parts.

The intake air flows through the air filter, intake boot (snorkel), then through the throttle body, into the intake manifold plenum, then through the runners, and into the cylinders. The throttle valve (body) controls the engine rpm by adjusting the amount of air flow.

11. Exhaust manifold

The exhaust manifold is generally simple cast iron or stainless steel units that collect engine exhaust gas from multiple cylinders and deliver it to the exhaust pipe. It is connected to exhaust valves. Its construction is the same as the inlet manifold.

The exhaust manifold has the same function in both petrol and diesel engines, in both cases, it carries exhaust gas.

12. Intake and Exhaust valves

Inlet and exhaust valves are used to control and regulate the charge (or air) coming to the engine for burning and exhaust gases going out from the cylinder respectively.

They are provided either on the cylinder heads or on cylinder walls. They commonly have a mushroom-shaped head.

In the case of Petrol engines, air and fuel mixture enters through the inlet valve. But in diesel engines, only air enters through the intake valve. The exhaust valve in both cases is meant for letting exhaust gases out.

Intake valves are connected to the intake manifold and exhaust valves are connected to the exhaust manifold. Both intake and exhaust manifolds are discussed above.

13. Spark plug

A spark plug is a device for delivering electric current from an ignition system to the combustion chamber of a spark-ignition engine to ignite the compressed fuel/air mixture by an electric spark while containing combustion pressure within the engine.

A spark plug has a metal threaded shell, electrically isolated from a central electrode by a ceramic insulator. The central electrode, which may contain a resistor, is connected by a heavily insulated wire to the output terminal of an ignition coil or magneto.

14. Connecting Rod

A connecting rod is the part of a piston engine that connects the piston to the crankshaft. Together with the crank, the connecting rod converts the reciprocating motion of the piston into the rotation of the crankshaft.

The connecting rod is required to transmit the compressive and tensile forces from the piston. In its most common form, in an internal combustion engine, it allows pivoting on the piston end and rotation on the shaft end.

The predecessor to the connecting rod is a mechanical linkage used by water mills to convert the rotating motion of the water wheel into reciprocating motion.

15. Piston Ring

A piston ring is a metallic split ring that is attached to the outer diameter of a piston in an internal combustion engine or steam engine.

The main functions of piston rings in engines are:

  • Sealing the combustion chamber so that there is minimal loss of gases to the crank case.
  • Improving heat transfer from the piston to the cylinder wall.
  • Maintaining the proper quantity of the oil between the piston and the cylinder wall
  • Regulating engine oil consumption by scraping oil from the cylinder walls back to the sump.

Most piston rings are made from cast iron or steel.

16. Gudgeon pin

A gudgeon pin, also known as a wrist pin, is an important component in an internal combustion engine. It creates a connection between the connecting rod and the piston. Gudgeon pins can also be used with connecting rods and wheels or cranks.

17. Cam

These are an integral part of camshafts. Due to cams, a camshaft is known as a camshaft. The cams are mounted on the camshaft to control the inlet and exhaust valve timing.

18. Flywheel

A flywheel is a mechanical device that uses the conservation of angular momentum to store rotational energy; a form of kinetic energy proportional to the product of its moment of inertia and the square of its rotational speed.

The torque provided by the engine is not uniform and is fluctuating in nature. If a vehicle continues to move with this fluctuating power. It will cause huge discomfort to the rider and also it will decrease the life of its different parts.

Hence to deal with the problem of fluctuating load a flywheel is used. A flywheel is generally mounted on the camshaft.  It stores torque when its value is high and releases it when its value is low in a cycle of operation. It acts as a torque buffer.

19. Gasket

A gasket is a ring or sheet composed of a supple material used in static applications to seal joints, flanges, and other mating surfaces to prevent leakage.

These are different types of gasket generally used in an engine:

  • Head gasket: A head gasket provides the seal between the engine block and cylinder head. Its purpose is to seal the combustion gases within the cylinders and to avoid coolant or engine oil leaking into the cylinders. Leaks in the head gasket can cause poor engine running and/or overheating.
  • Intake manifold gasket: The intake manifold gasket seals off the small gap between the manifold and the engine, preventing air, coolant, and oil from leaking. Over time, the intake manifold gasket endures a lot of wear and tear. Eventually it may crack or warp in ways that allow leaks to occur.
  • Exhaust manifold gasket: The exhaust manifold gasket is usually a multi-layered gasket that contains metal and other materials that are designed to provide the best seal possible. As the exhaust manifold gasket is the first in the exhaust system, it is a very important seal that should be inspected if any problems arise.
  • Water pump gasket: The water pump gasket is a ring-like part made of a durable material that can withstand varying temperatures. The water pump is one of the main components that pushes coolant around the engine, so a leak could start between it and the engine block if it does not have a well-fitting water pump gasket to keep it sealed.
  • Oil pan gasket: The oil pan gasket itself seals the oil pan to the bottom of the engine block and prevents oil from leaking as it moves from the pan to the engine and back. Because oil is constantly flowing, no vehicle is impervious to oil leaks, though. Often oil leaks stem from the oil pan or from a worn oil pan gasket.

20. Cylinder Liner

A cylinder liner is a thin metal cylinder-shaped part to be fitted into an engine block to form a cylinder. It is one of the most important functional parts to make up the interior of an engine. The cylinder liner, serving as the inner wall of a cylinder, forms a sliding surface for the piston rings while retaining the lubricant within.

During use, the cylinder liner is subject to wear from the rubbing action of the piston rings and piston skirt. This wear is minimized by the thin oil film which coats the cylinder walls and also by a layer of glaze that naturally forms as the engine is run in.

21. Crank Case

A crankcase is the housing for the crankshaft in a reciprocating internal combustion engine. In most modern engines, the crankcase is integrated into the engine block.

Two-stroke engines typically use a crankcase-compression design, resulting in the fuel/air mixture passing through the crankcase before entering the cylinder(s). This design of the engine does not include an oil sump in the crankcase.

Four-stroke engines typically have an oil sump at the bottom of the crankcase and the majority of the engine’s oil is held within the crankcase. The fuel/air mixture does not pass through the crankcase in a four-stroke engine, however, a small amount of exhaust gasses often enters as “blow-by” from the combustion chamber.

The crankcase often forms the lower half of the main bearing journals (with the bearing caps forming the other half), although in some engines the crankcase completely surrounds the main bearing journals.

22. Engine Distributor

A distributor is an enclosed rotating shaft used in spark-ignition internal combustion engines that have mechanically timed ignition. The distributor’s main function is to route secondary, or high voltage, current from the ignition coil to the spark plugs in the correct firing order, and for the correct amount of time.

Except in magneto systems and many modern computer-controlled engines that use crank angle/position sensors, the distributor also houses a mechanical or inductive breaker switch to open and close the ignition coil’s primary circuit.

23. Distributor o ring

Distributors commonly employ a specifically sized o-ring that fits on the distributor’s shaft to seal it with the engine referred to as the distributor o-ring.

The distributor o-ring simply seals the distributor housing with the engine to prevent oil leaks at the base of the distributor. When the o-ring fails it can cause oil leaks from the base of the distributor, which can lead to other problems.

24. Cylinder head cover

In many modern four-stroke engines, the cylinder head cover houses the upper actuation elements of the engine control unit as well as the valves in the crankcase ventilation with all its peripheral devices. Additionally, it protects the engine from dirt or other foreign objects.

25. Rubber grommet

Rubber grommets are used to protect or cover holes and reduce vibration. Inserting a rubber grommet will help eliminate sharp edges and protect the engine valve to pass through a hole. The rubber grommet will help shield the valve from damage.

26. Camshaft Pulley

A cam pulley is part of the timing system in an engine used to control the rate of rotation of the camshaft, the component that controls the poppet valves responsible for air intake and exhaust in the cylinders.

The cam pulley articulates with the timing chain to rotate the camshaft in synchronicity with the crankshaft.

27. Oil Filter

Your car’s oil filter removes waste, too. It captures harmful debris, dirt, and metal fragments in your motor oil to keep your car’s engine running smoothly. Without the oil filter, harmful particles can get into your motor oil and damage the engine. Filtering out the junk means your motor oil stays cleaner, longer.

28. Timing belt drive pulley

A timing belt pulley is a specialized pulley system with teeth or pockets along the outside of the pulley body’s diameter. The teeth or pockets on the outside of the pulley are not used for power transmission. Rather, they engage the pulley belt, assisting with timing and averting misalignment.

29. Water Pump

A vehicle’s water pump is a belt-driven pump that derives its power from the crankshaft of the engine. Designed as a centrifuge, the water pump draws the cooled fluid from the radiator through the pump’s center inlet. It then circulates the fluid outward into the engine and back into the car’s cooling system.

30. Oil pan drain bolt

The oil drain plug is typically located on the bottom of the engine on the oil pan. It is used to drain the oil from your pan during an oil change. If you notice a leak at the oil plug, in some cases it can be as simple as replacing the gasket.

If the bolt or oil pan has been cross-threaded, you may need a new oil drain plug. In some cases, an oversized oil drain plug will cut new threads to help you avoid replacing the entire oil pan.