Cooling Systems

Question 1

Why must an internal combustion engine have a cooling system?

Answer 1

To remove excess heat from the engine and to maintain a constant “safe”
operating temperature. The engine would be seriously damaged if the
excess heat was not removed.

Question 2

When heat energy moves
along a solid object and
into another solid object
that is touching it.

Answer 2

Conduction

Question 3

When heat energy is
transferred by a moving
liquid or gas. From hot to cold.

Answer 3

Convection

Question 4

When heat energy is 
transferred in wave form, with no physical 
contact between the heat 
source and the heated 
object.

Answer 4

Radiation.

Question 5

True or false? When heat is removed it can cause an object to become
smaller.

Answer 5

True.

Question 6

True or false? When enough heat is added to water it will begin to boil and
turn to vapour. This is called a “change of state”.

Answer 6

True.

Question 7

True or false? Heat will always move from a cooler region to a warmer region

Answer 7

False!

Question 8

True or false? Heat can change the colour of metals

Answer 8

True.

Question 9

A cooling system that uses only air to remove excess heat from the engine and take it directly to the atmosphere. The air can be forced past the engine
by a fan and guided by shrouds and ducts. Or simply by a draught type air flow.

Answer 9

Direct cooling system.

Question 10

A cooling system that uses liquid coolant to remove heat from the engine. The coolant is pumped through chambers inside the engine, called water-jackets. The liquid coolant absorbs heat from the engine and is
then pumped to a radiator mounted outside the engine where the heat is exposed to cooler air. The coolant then re-enters the engine to absorb more
heat and continue the cycle.

Answer 10

Indirect cooling system

Question 11

ON a DIRECT cooling system what is meant by the term “draught air flow”?

Answer 11

Draught air flow is when the air near the engine becomes hotter and begins to rise. The air rises because the molecules become less dense and thus lighter.
This allows denser cooler air to come in underneath where the hot air vacated and continue the cycle.

Question 12

Three types of cooling system fans that are used on

indirect cooling systems.

Answer 12

Flex fan
Thermostatic fan (variable speed fan)
Electric fan

Question 13

True or false? Both direct and indirect cooling systems can use a thermostat to control engine temperature.

Answer 13

True

Question 14

True or false? An indirect cooling system uses cooling fins.

Answer 14

False, most of the time.

Question 15

True or false? An Indirect cooling system uses a water pump

Answer 15

True

Question 16

True or false? A direct cooling system will have frost plugs.

Answer 16

False!

Question 17

Receives an electronic signal from the
temperature sender unit to show the
engine temperature to the driver

Answer 17

Temperature gauge

Question 18

Pumps coolant around the engine and

through the radiator

Answer 18

Water pump

Question 19

To seal holes in the engine left over from the casting process.
They pop out if the coolant freezes.

Answer 19

Frost plug / Welsh plug

Question 20

Stores excess coolant from the radiator
and allows it to be drawn back to the
radiator as it cools.

Answer 20

Coolant reservoir

Question 21

Controls the engine temperature. It remains
closed at start-up forcing the coolant to
cycle inside the engine until operating
temperature is reached. It then opens and
allows the coolant to flow through the
radiator. It then maintains a constant
engine temperature.

Answer 21

Thermostat

Question 22

Used to connect the engine and the water pump to the

radiator.

Answer 22

Radiator hose

Question 23

Mixture of water and ethylene glycol

Answer 23

Coolant / anti freeze.

Question 24

Allows hot coolant to be exposed to a cooler air flow

Answer 24

Radiator

Question 25

What is the name of the act that deals with the proper methods of
disposing of workshop waste such as coolant?

Answer 25

Resource management act

Question 26

Describe how old coolant should be properly disposed of.

Answer 26

Coolant must be stored for collection. So as that it can be properly disposed by the quallified waste management service. We use ExOil.

Question 27

What does testing the specific gravity of coolant tell you about the
composition of the coolant?

Answer 27

It measures the density of the coolant which will indicate how much antifreeze is in the coolant and whether it needs to be topped
up or replaced.