Cooling Systems (LJ 1)

Which of the following would be a typical working temperature for the coolant in a water cooled system?

• 27 °C

• 38 °C

• 100 °C

• 2,500 °C

Answer explanation

In a water-cooled system, the coolant typically operates around 100 °C, which is effective for heat transfer without boiling. The other temperatures are either too low or unrealistically high for standard cooling systems.

Which of the following would indicate that you were looking at a crossflow radiator?

• The core tubes are vertical

• The radiator is mounted horizontally

• The transmission fluid cooler is at the bottom

• The header and return tanks are on the sides

Answer explanation

A crossflow radiator is characterized by being mounted horizontally and having header and return tanks on the sides, allowing for efficient cooling. The other options do not specifically indicate a crossflow design.

What happens when the engine is cold in the thermostat operation?

• The thermostat opens fully

• The thermostat remains closed

• The thermostat opens partially

• The thermostat malfunctions

Answer explanation

When the engine is cold, the thermostat remains closed to allow the engine to reach optimal operating temperature quickly. This prevents coolant from circulating through the radiator, ensuring the engine warms up efficiently.

When the temperature of the coolant rises, what happens to the pressure in the cooling system?

• The pressure increases

• The pressure decreases

• The pressure remains constant

• The pressure fluctuates

Answer explanation

As the temperature of the coolant rises, the kinetic energy of the molecules increases, leading to higher pressure in the cooling system. Therefore, the correct answer is that the pressure increases.

In a closed cooling system, the excess hot coolant escapes from:

• the radiator cap

• the overflow tank

• the coolant reservoir

• the pressure relief valve

Answer explanation

In a closed cooling system, excess hot coolant escapes from the overflow tank, which is designed to handle excess pressure and coolant when the system heats up, preventing damage to other components.

The main purpose of rubber hoses in the cooling system is to:

• transfer coolant between engine components

• provide structural support to the engine

• insulate the engine from heat

• act as a filter for impurities

Answer explanation

The main purpose of rubber hoses in the cooling system is to transfer coolant between engine components, ensuring efficient temperature regulation and preventing overheating.

Hoses are constructed using synthetic yarn, styrene rubber, and other synthetic materials. True or False?

• True

• False

Answer explanation

True. Hoses are indeed made from synthetic yarn, styrene rubber, and other synthetic materials, which provide durability and flexibility for various applications.

The main purpose of the cooling fan is to generate ______ across the radiator.

• airflow

• heat

• vibration

• noise

Answer explanation

The main purpose of the cooling fan is to generate airflow across the radiator, which helps dissipate heat effectively. The other options, such as heat, vibration, and noise, do not align with the fan's primary function.

What is the usual composition of coolant?

• 70% water and 30% ethylene glycol

• 50% water and 50% ethylene glycol

• 30% water and 70% ethylene glycol

Answer explanation

The usual coolant composition is 50% water and 50% ethylene glycol. This balance provides effective heat transfer and prevents freezing, making it the most common mixture used in automotive and industrial applications.

What is one of the functions of coolant in a vehicle's cooling system?

• It increases the freezing point of water

• It prevents rust and corrosion

• It decreases the boiling point of water

Answer explanation

One of the key functions of coolant is to prevent rust and corrosion in the engine and cooling system components, ensuring longevity and efficient operation.