Components and Terminology of Engine External Parts

A glossary of engine external parts, as applied to automotive internal combustion engines.

The human body works by biological processes and chemical reactions taking place in the bloodstreams and hormones. Similarly, an internal combustion engine combines physical objects (parts) interacting with one another to produce motion.

Engine parts are very diverse - they come in many shapes and sizes depending on what they do and how they function. Each has its purpose, and each interacts with other parts to accomplish various tasks: like producing motion/power, transmitting power from the crankshaft, etc.

Learning about individual parts helps you learn about the whole system that makes up your vehicle's motor. This knowledge ranges from simple things like knowing what a rocker arm does to understanding how the oil pump works. Below is a list of some engine components and terminology that delve further into each subject.

1. Intake Manifold

The metal housing fitted to the front of the engine, which houses the intake funnels or carburetors.

2. Port Opening(s)

The holes in the intake manifold where each cylinder's intake funnel attaches to take in air and fuel mixture. "PORT" is often painted onto these openings for decoration purposes.

3. Exhaust Manifold

The metal housing fitted to the rear of an engine that houses exhaust pipes leading from each cylinder opening to a central pipe leading into the exhaust muffler outside the car body.

4. Cylinder Block

The large block inside an internal combustion engine that contains its cylinders, pistons, valves, etc.

5. Cylinder Head

The part of an engine that contains its cylinders, valves, spark plugs, etc. The "head" is the only part of the engine in contact with the fuel/air mixture.

6. Valve Train

The system comprises cams, levers, and valves that open and close each cylinder's intake and exhaust ports.

7. Crankcase

The block below a cylinder head from where pistons are connected to a crankshaft via a connecting rod assembly in a car's internal combustion engine

8. Connecting Rods

The rods used in a car's internal combustion engine to connect the piston to the crankshaft so that when one is pushed down by combustion, the other is pushed up via a crankshaft to produce rotational motion.

9. Oil Pan

The pan fitted under a car's engine and connected to its sump, which houses the oil pump. It catches any oil that may leak from gaskets or seals and drains it back into the engine via an external pipe connected to its bottom side.

10. Sump

A metal plate fitted around an oil pan which prevents excess oil from leaking out of the car during changes in level, such as going over bumps, etc.

11. Cylinder Head Gasket

A copper ring set between a cylinder head, and its engine block, which helps seal it hermetically to prevent leakage between the two mating surfaces.

12. Piston Ring

A circular ring connected to a piston and designed to seal its combustion chamber against loss of fuel/air mixture and subsequent escape of exhaust gases during the engine's compression cycle.

13. Main Bearing

The bearing in an engine's crankshaft assembly which supports its entire weight so that other bearings such as the conrod bearings can be smaller, lighter, and thus more effective at producing rotational motion.

14. Connecting Rod Bearing

The bearing in a car's connecting rod assembly reduces friction between it and the crankpin it slides along on a crankshaft by a rolling contact surface made up of oiled layers of steel and lead.

15. Roller Bearing

A type of bearing in a car's connecting rod assembly which uses a series of rollers instead of a sliding action between the bearing surfaces to reduce friction and improve rotational speed under load.

16. Crankpin

The pin around which one end of a connecting rod assembly rotates as it moves up and down during an engine's operation

17. Oil Pump

A device that pumps oil from the sump underneath an engine crankshaft up through connected pipes into its main bearings to prevent them from overheating/cooling too much due to their direct exposure to hot/cold moving air and fuel/air mixture during combustion within its cylinders.

18. Flywheel 

A large circular metal disk fitted to a car's engine crankshaft to add momentum and weight to help its moving parts last longer.

19. Thermostat

A valve in an engine that opens and closes at a specific temperature/fluid pressure combination to keep the engine from overheating or freezing during cold weather.

20. Muffler

A device attached to an internal combustion engine's exhaust manifold which reduces its noise output by way of disrupting the flow of hot exhaust gases through it via sound waves.

21. Air filter 

A filter added to an internal combustion engine's intake manifold (or carburetor) via which air can pass, but solid matter such as dust, pollen, etc., cannot. It improves engine performance by allowing it to draw in clean air and preventing any particles from reaching its pistons, valves, or other moving parts that may affect its smooth operation.

22. Carburetor 

A device attached to an internal combustion engine's intake manifold which mixes air with the fuel/air mixture to help it burn more efficiently for improved power output, reduced fuel consumption, and less exhaust emissions.

23. Fuel pump

A device connected to a car's fuel tank via pipes that pressurize it to allow the flow of gasoline into the carburetor at a rate appropriate for each phase of its four-cycle operation (intake, compression, combustion, exhaust).

24. Spark plug 

A device connected to an internal combustion engine's cylinder head(s) via which ignition of the fuel/air mixture within them occurs.

25. Injector 

A device connected to a car's engine cylinder head(s), via which gasoline is injected into each one at the appropriate time during its four-cycle operation to help maintain a high level of power and reduce exhaust emissions created by incomplete combustion due to not all the fuel being burnt correctly.

26. Fuel tank

A container for holding gasoline that feeds it through pipes into a car's carburetor or injectors to be available for use by its motor during normal driving operations.