A motor vehicle engine is a complex machine that burns fuel to produce power. Actually, it is the heart of your car. It converts fuel into mechanical energy. This energy turns the wheels, so you can move your vehicle forward.
You can see the engine as one unit, but many different parts work together inside it. We prepared this detailed article to explain automobile engine parts and their functions.
List of Automobile Engine Components
1. Engine Block
Engine block (cylinder block) is the backbone of an internal combustion engine. This component is generally made from cast iron or aluminum alloys. It holds several engine parts such as pistons, connecting rods & crankshaft. Mainly, it consists of three units. These include cylinders, ports for valves and channels.
It also has coolant passages and oil passages (oil galleries). They lubricate moving parts and control engine temperature. Sometimes, engine blocks use a separate crankcase to support crankshaft. You can find this design in large, stationary and marine engines.
2. Cylinder Head
You will see the cylinder head on the top of the engine block. It is used to close the upper portion of the cylinders and forms upper part of the combustion chamber. V shaped or boxer engines commonly have two cylinder heads (one for each group of cylinders).
However, inline engines have one cylinder head only. They are available in cast iron or aluminum. You can use bolts/studs to fix a cylinder head tightly to the engine block. Based on the arrangement of the valves & ports, these are cylinder head designs.
- Loop-flow design has intake and exhaust ports on the same side of the cylinder head.
- Cross-flow design system has intake & exhaust ports on opposite sides of the cylinder head.
3. Engine Pistons
The piston is a cylindrical metal part. It moves up and down inside the cylinder. The job of this component is to receive pressure from the burning fuel-air mixture and transfer that force to the connecting rod.
The piston’s highest position is called top dead center (TDC). And its lowest point is known as bottom dead center (BDC). You should always choose engine pistons that are strong enough to handle high pressure and heat.
4. Engine Piston Rings
You will see piston rings around engine pistons. They seal the gap between the piston and cylinder wall. In addition, these rings block entry of high pressure combustion gases to the crankcase. There are several grooves on the piston where you can install these rings.
For their production, you should prefer either cast iron or steel alloys. In the market, you can mainly find two types of piston rings. These are oil control rings and compression rings. According to the design of your automobile engine, you can use around two to four compression rings and one to two oil control rings.
5. Piston Pin
The piston pin is also called the wrist pin (common in the US & Canada) and gudgeon pin (in the UK). You need this part for the engine to link the piston with the connecting rod. Along with the up & down movement of the piston, the connecting rod also needs to move at an angle.
This pin lets the rod swing as well as stay connected to the piston. For manufacturers, we recommend you make the piston pin hollow to reduce its weight. Below we list the main types of piston pins available in the market.
- Set-screw type pin stays fixed in the piston with a set screw.
- Semi-floating type pin is secured to the connecting rod with a clamp or similar fastener.
- Fully floating type pins can move and rotate inside both the piston and connecting rod.
6. Connecting Rods
The connecting rod joins the piston to the crankshaft. Its main job is to transfer the piston’s reciprocating motion to the crankshaft. Then the crankshaft will convert that motion into rotary motion. In most cases, you will find connecting rods in EC engines and IC engines.
They are made of strong materials like forged steel & aluminum alloy. It has an I-beam cross-section. The small end of this rod connects to the piston and its big end is linked to the crank pin of the crankshaft.
7. Crankshaft
The crankshaft is a major moving part inside the engine. You can notice it inside the engine block. It consists of several other items like crankpins, crank webs, oil hoses and balancing weights. To join connecting rods with crankshaft, you can use crankpins. So when pistons move up and down, the rods will push/pull the crankshaft and cause it to rotate.
You will find three important parts at the front end of the crankshaft. These are gear, vibration damper & fan belt pulley. Well, you can use these methods to build a crankshaft.
| Crankshaft Type | Feature |
| One-piece | Entire crankshaft is made as one solid piece |
| Semi-integral | Some parts are made separately and then joined together |
| Welded | Different crankshaft sections are joined by welding |
8. Valvetrain
Valvetrain is a group of engine components located in and around the cylinder head. They control the intake and exhaust valves. A valve train also includes various other parts that we listed below.
- Camshaft
- Lifters
- Pushrods
- Rockers arms
- Bucket tappets and finger followers
- Valves and valve springs
9. Camshaft
The camshaft is a rotating shaft with raised sections called cam lobes. It controls when the engine’s intake and exhaust valves open & close. The crankshaft basically drives the camshaft. In a four-stroke engine, the camshaft always turns at half the speed of the crankshaft.
Mostly, camshaft gear has more teeth than the crankshaft gear. There are three main camshaft operating mechanisms: gear drive, chain drive & belt drive. Following engine components are also connected directly to the camshaft system.
- Camshaft pulley (toothed wheel) connects the camshaft to the timing belt/timing chain
- Rocker arms work with the camshaft to press the valves open
Informative: In modern overhead-cam (OHC) engines, you will find a camshaft in the cylinder head. A dual overhead cam (DOHC) engine uses two camshafts for each bank of cylinders.
10. Timing Chain/Belt
Timing chain or belt is the important part of the internal engine that you can use to connect the camshaft to the crankshaft. It keeps both shafts moving together, so the valves open and close at the correct time. Due to this proper timing, the engine of your vehicle can run smoothly and produce power.
11. Engine Spark Plugs
It is a small electrical piece that you will observe in gasoline internal combustion engines. These plugs are used to create a spark in the cylinder. They are also linked to the ignition coil, which produces the high voltage needed to create the spark.
So when the spark jumps across the gap at the end of the plug, it starts burning compressed air-fuel mixture. This combustion will create pressure and push the piston down. As a result, the power will be generated to run the engine.
12. Engine Oil Pan/Sump
The bottom section of the crankcase contains the oil pan. It is made from pressed steel sheet or aluminum alloy. You can also call it a sump. Basically, this part serves as a reservoir for engine oil. Plus, this portion stores, cools and helps ventilate the lubricating oil. You will also find a drain plug at its bottom, which lets you remove old oil during an oil change.
Fact: Most oil pans are able to hold around four to six quarts of oil. If you want to check the exact oil level, we suggest you use a dipstick. It can easily reach down into the oil pan.
13. Engine Valves
During the operation of an internal combustion engine, these valves control the flow of air & exhaust gases. You will find these valves in the cylinder head. They open and close at the correct time, so the engine can complete its working cycle. Another purpose of them is to seal the cylinder during combustion. In a standard automobile engine, you will see two types of valves.
- Intake valves open to let an air-fuel mixture enter the cylinder.
- Exhaust valves will open after combustion to allow burned exhaust gases to leave cylinder.
14. Combustion Chamber
It is the space inside the cylinder where the engine burns the air-fuel mixture to produce power. Engineers add this section to create an area between the cylinder head & piston. This chamber is connected with an exhaust valve, piston, intake valve and spark plug.
There is a reason why you should choose its size and shape carefully. According to experts, its design affects the engine’s compression ratio, power, fuel consumption and its efficiency. You will find these chambers in ships, cars, aircraft, trucks & buses engines.
15. Engine Flywheel
This is a heavy wheel which you can see attached to the rear of the crankshaft. It stores some of the engine’s rotating energy through its inertia. This way, it keeps the crankshaft turning at a more uniform speed when your car engine produces power in cycles as well as running smoothly at idle.
In vehicles with a manual transmission, the clutch attaches to the flywheel. The size of the flywheel you need totally depends on factors such as the number of cylinders and the engine design in your automobile.
16. Head Gasket
Head gasket present in the middle of the engine block or cylinder head plus crankcase & oil pan. The major role of this unit is to create tight and leak-resistant joints. It also keeps gases, engine oil and coolant in their proper passages.
Common gasket materials are cork, asbestos & rubber. Common types of engine gaskets you can find in the market include cylinder head gaskets, oil pan gaskets, manifold gaskets & pump gaskets.
17. Cylinder Liner
A cylinder liner (cylinder sleeve) is a hollow metal tube. It is fixed inside the cylinder bore of the engine block. Its job is to provide a smooth and strong surface for the piston to move inside the cylinder.
The liner also protects the engine block from wear and damage. So that, you can easily repair or replace the damaged cylinder surface if needed. It has two varieties.
- Dry liner fits directly inside the cylinder block and its outer surface does not touch the coolant
- Wet liner directly touches the coolant on its outer surface
18. Engine Distributor & Distributor O-Ring
A distributor is a spark system component that you mostly find in older gasoline engines. It sends the high-voltage current from the ignition coil to each spark plug. This way, the air-fuel mixture will burn at the correct time during the engine cycle. It is connected to the camshaft, spark coil and spark plugs.
If we talk about a distributor O-ring, it is a small and round rubber ring. You need to install it to seal the distributor housing to the engine. It helps prevent oil leaks around the distributor base.
19. Cylinder Head Cover
This cover is located on top of the cylinder head. You can use it to seal the upper section of the engine and keep its oil inside. Oil mist and combustion gases also collect under this cover.
It is also perfect to secure the valvetrain components such as valve springs, camshaft & valves. They are generally made from aluminum alloy or other lightweight materials.
20. Engine Cover Rubber Grommets
An automotive grommet is a small rubber ring. You will notice it fitted into a hole in the vehicle’s body or engine parts. Its primary function is to protect tubes, hoses, electrical wires, cables from sharp metal edges cuts. In short, these rings basically create a small cushion between the engine cover and its mounting points.
21. Starter Motor
The starter motor is a small electric motor used to start the engine if you turn the key or press the start button. It takes power from the battery to turn the crankshaft and start vehicle engine. This motor has a small pinion gear. It linked with the ring gear on the flywheel.
This connection turns the crankshaft and moves the pistons. It will start the normal operation of the engine. Once the engine starts, the starter motor will disconnect from the flywheel.
22. Air Intake System
In an automobile engine, this system is responsible for bringing fresh air into the engine. The engine needs this air to mix with fuel and produce power. This setup includes multiple parts such as the air filter, rubber air intake hose, throttle body and intake manifold. The air filter removes dirt and dust from the incoming air and other parts guide the clean air into the engine.
23. Fuel Delivery System
The purpose of the fuel delivery system is to supply fuel to the engine and make sure it gets right amount of fuel for combustion. This setup includes fuel lines, a fuel pump and fuel injectors or a carburetor.
All of them work together to transfer fuel from the fuel tank to engine. It delivers fuel at the right pressure and at the right time. As a result, your vehicle engine can start easily and produce the power your car needs to work properly.
24. Throttle Body
This piece controls the amount of air that enters the engine. It is present between the air intake system and the engine’s intake manifold. Suppose you press the accelerator pedal, then the throttle body will open to let more air into the engine.
But when you release the pedal, it will close and reduce the airflow. In this way, your car engine can better control its speed (RPM) and power.
25. Fuel Injectors
Fuel injectors spray a small amount of fuel into the engine. They mix the fuel with incoming air, so the engine can burn the mixture and produce power. There are different types of fuel injection systems and an engine normally uses one of them.
- Direct fuel injection
- Port fuel injection
- Throttle body fuel injection
26. Manifolds
Manifolds are sets of pipes which you will find connected to the cylinder head. They carry the air-fuel mixture into the engine and carry exhaust gases away from the cylinders as well. In a vehicle engine, there are two types of manifold present.
First is the Intake manifold, which carries the incoming air or air-fuel mixture. You will observe it after the air intake system. On the other hand, exhaust manifolds transfer hot exhaust gases away from the engine.
27. Engine Water Pump (Coolant Pump)
Engineers fit a water pump to move coolant through the engine’s cooling system. It sends coolant through the engine block and cylinder head to absorb heat from the engine. The pump then moves the hot coolant toward the radiator. At this point, coolant will release heat before it returns to the engine.
28. Engine Radiator
An engine radiator is a thin and rectangular metal panel with many small tubes and fins. It is mostly located at the front of the engine bay. The role of radiator is to remove heat from the engine coolant.
The cooled liquid then flows back to the engine through the water pump. This continuous process keeps your car engine at a safe operating temperature and prevents overheating.
29. Coolant Hoses
Coolant hoses are thick and flexible rubber or silicone tubes. They are installed to connect different parts of the engine cooling system. These pipes carry coolant between the engine, radiator, water pump and other parts of cooling system.
Most vehicles have an upper radiator hose and a lower radiator hose. These hoses are available in different lengths, shapes and sizes.
30. Turbocharger & Supercharger
A turbocharger and supercharger are engine parts that force more air into the engine. You will find them as a round metal housing and linked to the engine’s air intake system. A turbocharger uses exhaust gases to spin a turbine. Plus, a supercharger uses engine power to drive a compressor.
Final Note
Every engine component has an important job regardless if it is large or small. In case one of them fails, it can affect the overall performance of engine or stop it from working properly.
The information about these components can make vehicle maintenance much easy for you. In fact, you can better understand a mechanic’s recommendations, describe problems more clearly and choose the right replacement parts.
FAQs
Which Engine Part Causes Rough Idle?
There is not only a single item behind the rough idle condition of your car. Common causes can be worn spark plugs, a dirty throttle body or a vacuum leak caused by a cracked or damaged hose.
How Often To Replace Timing Belt?
Our suggestion is to change your vehicle engine timing belt every 60000 to 100000 miles or every 5 to 10 years (whichever comes first). It means you should consider both mileage and time when you are planning a belt replacement.
What Should I Use To Clean Engine Parts?
For light grease and general cleaning of engine components, you can use brake cleaner, hot water with dish soap or mineral spirits. But if you need to clean heavy grease and carbon deposits, stronger degreasers or kerosene are the best options.
Who Invented Automobile Engine?
There were several inventors & engineers involved in the development of engines you can see in vehicles today. Nikolaus Otto developed the four-stroke engine design in 1876. Karl Benz later built a practical gasoline-powered car engine in 1885.
