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Your Guide to Car Engine Components and Functions

Not every motorist knows the car engine basics that will help them to keep their car running properly. In this guide, you will find out the basics of the internal combustion engine and the main difference between petrol and diesel engines and much more besides. This way, you will have a much better understanding of car engine parts and modern motor technology.

Read more: Guide: How to Maintain and Protect Your Car Engine

What are the basics of engines?

Searching for car parts online is now the norm for many motorists rather than seeking them out from individual car breakers which can be a time-consuming business. What you need to know is that many engine parts can be replaced quite easily so long as you understand the basics and have some rudimentary mechanical know-how.

Essentially, all engines are similar in nature. They mix fuel with air and release energy by burning them. This creates a linear force that is captured by multiple pistons, something that can be used to turn wheels and drive a vehicle forwards.

What are combustion engines?

There are two types of engines, the internal combustion engine and the external combustion engine. Both use combustion which simply means the process of burning something. With internal combustion engines, an air and fuel mixture is drawn into a combustion chamber where it is burned to force a cylinder forward.

Combustion gases expand in the combustion chamber which drives the engine’s cylinders outward, something that can be turned into rotational force to drive a vehicle forwards. This is how a car engine works. By comparison, external combustion relies on an outside ignition system, such as a coal fire to heat water. This is what you’d find in a steam engine.

What are the fundamentals of engine operation?

Modern engines, whether you are talking about a petrol or a diesel engine, have direct fuel injection systems that combine with an air intake system to create a combustible air fuel mix. This goes into the main body of the engine block, otherwise known as a cylinder block, usually made from a single piece of metal. In a spark ignition engine, the cylinder walls within the block contain the mini-explosion that occurs with each power stroke of the engine.


Intake valves help to shut off the combustion within the cylinder block so that the gas tank is not ignited. The fuel air mixture is ignited from spark plugs which operate from an electrical current. This forces a piston out because the ensuing burning gas tries to expand but is contained by the cylinder wall of the engine block in a gasoline engine.


With the piston pushed forwards, rotational motion can be obtained. This is called the combustion stroke but further energy can be obtained from a stroke engine if the compression stroke, when the piston returns to its former position, is captured, too. To do this, valve springs help exhaust valves to open and close depending on whether the piston is on its intake stroke or its exhaust stroke. In a four stroke engine, there are four phases:

  • The intake stroke which effectively sucks fuel in.
  • The compression stroke which closes the valves to create a momentarily sealed cylinder and to squash the fuel and air ready for combustion.
  • The power stroke which is caused by the combustion process itself.
  • The exhaust stroke which opens the exhaust valve in the cylinder head. When exhaust valves open they push exhaust gases into the exhaust system and eventually, the exhaust pipe.

Four cylinder engines have two pistons operating in tandem at any one moment. They use a timing belt to help ensure the pistons stay in alignment with one another.

What are the components parts of engine?

The cylinder head contains many of the components you will need for a car engine to run. For example, the cylinder head contains:

  • The head gasket
  • Spark plugs
  • Intake and exhaust valves

Other common engine components that are needed to improve the running of car engines so fuel economy can be maintained include the oil pan and the oil pump. The engine’s oil is essential so that engine performance can be maintained without overheating. The oil filter is also crucial in this regard.

As well as engine oil, all heat engine designs also need piston rings to keep them cool. A starter motor is essential to get the process of combustion up and running while the engine speed is maintained by a throttle body. Car manufacturers use connecting rods to transfer the back-and-forth motion of a piston to a crankshaft which drives the vehicle’s wheels via a camshaft. Many modern cars have a dual overhead camshaft these days to help with efficiency.

Searching for the right sort of car parts is not always easy because manufacturers use different ones and they are rarely interchangeable. Try searching with your car’s vehicle identification number so that compatible parts are easier to track down at places like Autoparts-24. Here, you can also find OEM car parts that have been made by third parties as well as manufacturers’ originals. Motorists can also use motorcodes to help them find the right sort of part for their engine. The common ones that people look for nowadays are listed below.

Engine Block

This is a single block of metal, usually steel, that creates the integral structure for the engine’s moving parts to work in.

Combustion Chamber

Made up of a cylinder, a piston and cylinder head, this is where the fuel is mixed with air and ignited.

Cylinder Head

Pieces of metal that sit over the engine block’s cylinders, cylinder heads create space for combustion to occur at the top of the chamber.


As you have read, pistons move back-and-forth within each cylinder.


This component convents the back-and-forth motion of a piston and turns it into rotational force.


Along with the crankshaft, the camshaft keeps all of the cylinders working together, ensuring the valves operate in a coordinated way.

Timing System

This system uses a belt or something similar to keep the camshaft in sync with the rest of the moving components of the engine.


This component keeps the valves over each cylinder opening and closing via a system of lifters, rocker arms and pushrods.


The valves stop more fuel and air getting into the combustion chamber when it is being ignited. They also help to release noxious gases from the engine in a safe manner.

Rocker Arms

These are arms that are pushed when the camshaft comes into contact with them so they can push up and down on valves at the right moment given the number of revolutions the car is producing at any given moment.

Pushrods and Lifters

If the engine’s design means that the camshaft doesn’t contact its rocker arms directly, pushrods or lifters will be used to form a physical connection between the two.

Fuel Injectors

Fuel injection systems have largely replaced old-fashioned carburettors nowadays. These components spray fuel into each cylinder directly so that just the right amount is delivered precisely where it is needed each time.


This is an electrical component that creates a spark when every new injection of fuel is delivered. This causes the combustion from which combustion engines are named to occur.

What are the 3 main components needed for an engine to run?

An important mechanical set of components that keeps engines running safely, a valve train consists of the valves themselves as well as rocker arms, a connecting rod and lifters.

Another crucial item for an engine to run smoothly is the intake manifold. Also called an inlet manifold, this device supplies the air and fuel to the cylinders in just the right quantities.

One of the other important components that can go wrong sometimes is the timing belt, part of the engine’s wider timing system. Essentially, this keeps the engine in sync with itself and helps to coordinate the camshaft and the crankshaft.

What are engine accessories?

It is important to note that some things under a car’s bonnet are not engine components but accessories that help them to run. For example, an oil sump is an accessory. It merely collects used oil so it can be filtered and used once more as engine oil. Your engine’s air filter helps similarly. This accessory helps to remove airborne particles that might otherwise get into the combustion chamber.

What do car engines run on?

There are two primary sources of fuel available today, petrol and diesel. Both have similar theories behind them and some common parts, such as a fuel injector, a connecting rod or a manifold. However, the design of each will vary a great deal depending on the type of engine. Few are compatible with each other.

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