How a Car Works: Engine Block

What is another name for the engine block?

The cylinder block, or simply the block.

What is the largest part of an engine?

The engine block.

What materials are engine blocks usually made from?

Cast iron or cast aluminum.

What is the primary function of the engine block?

To house the cylinders.

Where do the pistons move up and down?

Inside the cylinders.

What two important fluids circulate through passageways in the engine block?

Coolant and oil.

Why does coolant circulate through the engine block?

To keep the cylinders cool during combustion.

Why does oil circulate through the engine block?

To lubricate various engine components and reduce friction.

Why are engine accessories mounted to the engine block?

Because the block is strong enough to support their weight.

Name four accessories commonly mounted to the engine block.

Alternator, water pump, starter motor, and A/C compressor.

What material has been primarily used to construct engine blocks for the last 100 years?

Cast iron.

How were many early engines constructed before cast engine blocks became common?

They used individual cylinder components and brass pipes for oil and coolant.

Why did manufacturers switch to mass-produced cast engine blocks?

They were cheaper and easier to produce.

How are cylinders formed in cast iron engine blocks?

They are machined directly into the block.

What is used in aluminum alloy engine blocks to form the cylinders?

Cylinder liners inserted into bored holes.

Why must pistons run on a film of oil?

To reduce friction between the piston and cylinder wall.

What design is milled into cylinder walls to help retain oil?

A cross-hatch design.

What is the deck of an engine block?

The top surface of the block that meets the bottom of the cylinder head.

What component sits between the deck and the cylinder head?

The head gasket.

What is the purpose of the head gasket?

To form a seal between the block and cylinder head and contain combustion pressure.

How many decks does an inline engine have?

One deck.

Why do V-shaped and W-shaped engines have multiple decks?

Because each cylinder head requires its own deck.

What are the oil passageways inside the engine block called?

Galleries.

Where does the oil pump get oil from?

The sump

How does oil enter the galleries?

Through a feed pipe from the oil pump.

What is the purpose of the galleries?

To distribute oil throughout the engine, including to the cylinder heads.

Which area of the engine block receives the most lubrication?

The underside of the engine block.

What major component sits on saddles within the engine block?

The crankshaft.

What is the bottom area of the engine block that houses the crankshaft called?

The crankcase.

What are core plugs?

Plugs used to seal casting holes in the engine block.

Why must engine cylinders be kept cool?

To prevent pre-ignition and excessive thermal expansion.

What can happen if engine components become too hot and expand excessively?

Metal-to-metal contact may occur.

What is pre-ignition?

The fuel-air mixture igniting before the proper spark event due to excessive heat.

Describe the path coolant takes through the engine.

Coolant rises from the engine block to the cylinder head, then flows to the radiator system.

Why is coolant circulation important?

It helps maintain safe operating temperatures and prevents engine damage.