1. Carburetor
   PCV valve
2. EGR valve
   Air filter

Carburetors, replaced on modern automobiles by more precise and reliable fuel injection, mixed the air and fuel to the correct ratio needed for combustion.

1. Piston
   Spark plug
2. Glow plug
   Crankshaft

Each piston is attached to a connecting rod, which is joined to the crankshaft to turn it when the combustion cycle pushes the piston down in the cylinder.

1. Spark plug
   Distributor
2. Single overhead camshaft
   Crankshaft

“Single overhead camshaft,” or SOHC, refers to an engine with one camshaft that operates both the exhaust and intake valves. Double overhead camshaft uses one camshaft for the intake valves and another for the exhaust valves.

1. Hoses
   EGR valve
2. Intake manifold
   Water pump

A water pump moves coolant through the engine where the excess heat is transferred to it. The coolant then returns to the radiator, which dissipates the heat.

1. EGR valve
   Oil filter
2. Coil
   Carburetor

Oil keeps the moving parts of an engine lubricated, and an oil filter removes impurities in the oil that might damage the engine.

1. Glow plug
   Timing gears
2. Lug nuts
   Cylinder head bolts

Cylinder head bolts – or just “head bolts” – secure a cylinder head and gasket to the engine block.

1. Camshaft
   Oil pan
2. Balance shaft
   Valve cover

The valve cover is bolted onto the cylinder head, covering the camshafts (in an overhead-cam engine, which is the most common type) and the valves and their attendant hardware.

1. EGR valve
   Turbocharger
2. Passing gear
   Glow plugs

Driven by exhaust gases running through it, a turbocharger essentially pushes more air into the engine, which, in turn, creates more power as more fuel is burned.

1. Oil pump
   Electronic control unit
2. Fuel pump
   Water pump

The oil pump circulates oil within the engine.

1. Distributor
   Oil pump
2. Starter motor
   High tension leads

When you turn the key of your car (or push the ignition start button), the starter motor rotates the crankshaft to begin the combustion process.

1. Distributor
   Timing belt
2. High tension leads
   Crankshaft

You’ll find the distributor in the obsolete parts bin next to the carburetor. The distributor literally distributed electric current to the spark plugs in the correct order and intervals. In modern engines, the job is handled by a computer-managed ignition control module.

1. Water pump
   Air intake manifold
2. Fuel pump
   Oil pump

The fuel pump is self-explanatory: it moves the fuel from where it’s stored (the tank) to the engine.

1. Connecting rod
   Pushrod
2. Sprocket
   Cylinder liner

The cylinder liner is also known as a sleeve. It’s a replaceable, hollow tube made from iron that fits into the cylinder bore.

1. Turbocharger
   Sump
2. Fan belt
   Air filter

An air filter ensures the air entering the engine for mixing with fuel for combustion is kept clean of any particles that may damage the engine.

1. Throttle
   Intake valve
2. EGR calve
   Piston

Driven by a camshaft, the intake valves are located in the cylinder head. In most modern engines, there are two intake and two exhaust valves per cylinder.

1. Studs
   High tension leads
2. Cam bearings
   ECU

High tension leads, a.k.a. sparkplug wires, connect the spark plugs to the distributor. Well, that’s in an old engine. In a modern engine, individual ignition coils are usually placed right near or over the cylinders, with much shorter and usually hidden wires carrying current to them.

1. Fuel pump
   Fuel tank
2. Oil filter
   Fuel filter

A fuel filter will help to remove impurities that might be in the fuel which, if they get into the engine, can cause complications.

1. EGR valve
   Piston ring
2. Spark plug
   Glow plug

The spark plugs ignite the air-fuel mixture in the cylinders to start and run the engine.

1. Intercooler
   Turbocharger
2. Wastegate
   Blowoff valve

Found in turbocharged (and supercharged) engines, an intercooler is a small radiator that reduces the temperature of the air compressed by the turbocharger. This makes it denser when it is pushed through the engine and helps it to produce more power.

1. Oil pan
   Intake manifold
2. Crankshaft
   Cylinder head

Found at the bottom of the cylinder block, the oil pan serves as the oil reservoir

1. Radiator
   Oil pan
2. Intake manifold
   Thermostat

Coolant circulates through the radiator when the engine is running, and most of it is stored there when the engine is off. In modern cars, you check the level of coolant in the overflow tank, not the radiator.

1. Dual overhead camshaft
   Distinct overburned hydrocarbon
2. Double oil hyper cooler
   Dual oil hydroformed crankshaft

We generously gave you this answer in an earlier question about SOHC. “DOHC” means dual (or double) overhead camshaft, as opposed to SOHC, which is single overhead camshaft.

1. EGR valve
   Exhaust valves
2. Oil pan
   Glow plug

The intake and exhaust valves are found in the cylinder head. They’re opened by the camshafts and closed by the action of valve springs. The exhaust valves release the combustion gasses into the exhaust manifold, which empties into the exhaust pipe.

1. Fan belt
   Timing belt
2. Water pump belt
   Alternator belt

The timing belt is run off the engine’s crankshaft to turn the camshaft (or multiple camshafts) to operate the intake and exhaust valves in a precisely timed sequence – hence, it’s called a timing belt.

1. Pushrods
   Cam followers
2. Valves
   Throttle bodies

You should know this after earlier questions. The camshafts open intake valves to send the air/fuel mixture into the cylinders, and the exhaust valves let the combustion gases leave the cylinders.

1. Connecting rod
   Pushrod
2. Timing belt
   Piston ring

The connecting rod forms the mechanical link between the piston and crankshaft. It converts the piston’s up and down motion to the crankshaft’s rotary motion.

1. Cam follower
   Bearing
2. Cylinder liner
   Pushrod

A bearing is a curved metal piece that reduces friction between components. It comes in many different shapes and sizes.

1. Spark plug
   Engine block
2. Piston
   Glow plug

The cylinder block is the lower section of the engine, cast from either iron or aluminum and housing the reciprocating assembly (crankshaft, pistons, and connecting rods).

1. Carburetor
   Ignition control module
2. Electronic control unit
   Fuel injection

In modern engines, the electronic control unit (ECU) is a computer runs the show, ensuring optimal engine performance at all times.

1. Glow plug
   Bearing
2. Sprocket
   Camshaft

A sprocket is a wheel with a set of teeth on its outer circumference. It drives items like the timing chain or belt.

1. Connecting rod
   Rocker arm
2. Cam bearing
   Sprocket

In a pushrod-type engine (such as the current Chevrolet/GM V8 family), a single camshaft operates pushrods, which then transfer that motion to the rocker arms to open the intake and exhaust valves.

1. Fuel filter
   PCV valve
2. Intake manifold
   Fuel pump

The intake manifold ensures even distribution of the air/fuel mixture, although with modern direct fuel-injection systems, the intake manifold’s job is to direct, measure and throttle the air alone.

1. Crankshaft
   Balance shaft
2. Camshaft
   Timing belt

In many four-cylinder engines (and some V6 engines), balance shafts with off-center counterweights turn in opposite directions from each other at twice the engine speed, canceling vibrations. The idea was invented by a British engineer, Frederick Lanchester, in 1904 and came into common use in the 1970s.

1. Oil filter
   Oil control ring
2. Oil level sensor
   Thermostat

The oil control ring prevents oil from sneaking past the piston and reaching the combustion chamber. It comes under the umbrella of piston rings.

1. Camshaft
   Crankshaft
2. Main shaft
   Flywheel

As the combustion cycles push the pistons downward, their respective connecting rods rotate %0Dthe crankshaft. That rotation, going through the transmission as torque, ultimately causes the vehicle to move.