Inspecting & adjusting an engine drive belt

Part 1. Preparation and safety

Objective

• Inspect and manually adjust engine accessory drive belts.

Personal safety
Whenever you perform a task in the workshop you must use personal protective clothing and equipment that is appropriate for the task and which conforms to your local safety regulations and policies. Among other items, this may include:

• Work clothing - such as coveralls and steel-capped footwear
• Eye protection - such as safety glasses and face masks
• Ear protection - such as earmuffs and earplugs
• Hand protection – such as rubber gloves and barrier cream
• Respiratory equipment – such as face masks and valved respirators

Engine Cooling : Replacing an engine drive belt

Replacing an engine drive belt

Part 1. Preparation and safety

Objective

• Remove and replace an engine accessory drive belt.

Personal safety
Whenever you perform a task in the workshop you must use personal protective clothing and equipment that is appropriate for the task and which conforms to your local safety regulations and policies. Among other items, this may include:

• Work clothing - such as coveralls and steel-capped footwear
• Eye protection - such as safety glasses and face masks
• Ear protection - such as earmuffs and earplugs
• Hand protection – such as rubber gloves and barrier cream
• Respiratory equipment – such as face masks and valved respirators

Engine Cooling : Removing & replacing a thermostat

Removing & replacing a thermostat

Part 1. Preparation and safety

Objective

• Safely remove and replace a cooling system thermostat.

Personal safety
Whenever you perform a task in the workshop you must use personal protective clothing and equipment that is appropriate for the task and which conforms to your local safety regulations and policies. Among other items, this may include:

• Work clothing - such as coveralls and steel-capped footwear
• Eye protection - such as safety glasses and face masks
• Ear protection - such as earmuffs and earplugs
• Hand protection – such as rubber gloves and barrier cream
• Respiratory equipment – such as face masks and valved respirators

Engine Cooling : Removing & replacing a radiator

Removing & replacing a radiator

Part 1. Preparation and safety

Objective

• Safely remove and replace a radiator.

Personal safety
Whenever you perform a task in the workshop you must use personal protective clothing and equipment that is appropriate for the task and which conforms to your local safety regulations and policies. Among other items, this may include:

• Work clothing - such as coveralls and steel-capped footwear
• Eye protection - such as safety glasses and face masks
• Ear protection - such as earmuffs and earplugs
• Hand protection – such as rubber gloves and barrier cream
• Respiratory equipment – such as face masks and valved respirators

If you are not certain what is appropriate or required, ask your supervisor.

Engine Cooling : Testing cooling system pressure

Testing cooling system pressure

Part 1. Preparation and safety

Objective

• Test a cooling system to confirm that it is without leaks and has the ability to hold the pressure specified by the manufacturer.

Personal safety
Whenever you perform a task in the workshop you must use personal protective clothing and equipment that is appropriate for the task and which conforms to your local safety regulations and policies. Among other items, this may include:

• Work clothing - such as coveralls and steel-capped footwear
• Eye protection - such as safety glasses and face masks
• Ear protection - such as earmuffs and earplugs
• Hand protection – such as rubber gloves and barrier cream
• Respiratory equipment – such as face masks and valved respirators

Engine Cooling : Checking & replacing a coolant hose

Checking & replacing a coolant hose

Part 1. Preparation and safety

Objective

• Check, remove and replace coolant hoses.

Personal safety
Whenever you perform a task in the workshop you must use personal protective clothing and equipment that is appropriate for the task and which conforms to your local safety regulations and policies. Among other items, this may include:

• Work clothing - such as coveralls and steel-capped footwear
• Eye protection - such as safety glasses and face masks
• Ear protection - such as earmuffs and earplugs
• Hand protection – such as rubber gloves and barrier cream
• Respiratory equipment – such as face masks and valved respirators

Engine Cooling : Draining & refilling coolant

Draining & refilling coolant

Part 1. Preparation and safety

Objective

• Drain cooling system and refill with correct mixture of engine coolant.

Personal safety
Whenever you perform a task in the workshop you must use personal protective clothing and equipment that is appropriate for the task and which conforms to your local safety regulations and policies. Among other items, this may include:

• Work clothing - such as coveralls and steel-capped footwear
• Eye protection - such as safety glasses and face masks
• Ear protection - such as earmuffs and earplugs
• Hand protection – such as rubber gloves and barrier cream
• Respiratory equipment – such as face masks and valved respirators

Engine Cooling : Checking & adjusting coolant

Checking & adjusting coolant

Part 1. Preparation and safety

Objective

• Check and adjust coolant levels and test coolant quality in a vehicle with a recovery reservoir.

Personal safety
Whenever you perform a task in the workshop you must use personal protective clothing and equipment that is appropriate for the task and which conforms to your local safety regulations and policies. Among other items, this may include:

• Work clothing - such as coveralls and steel-capped footwear
• Eye protection - such as safety glasses and face masks
• Ear protection - such as earmuffs and earplugs
• Hand protection – such as rubber gloves and barrier cream
• Respiratory equipment – such as face masks and valved respirators

Engine Cooling : Cooling system components

• Radiator
• Coolant hoses
• Water pump
• Cooling system thermostat
• Cooling fans
• Temperature indicators
• Radiator pressure cap
• Recovery system
• Boiling point & pressure
• Electrolysis
• Centrifugal force
• Thermo-switch

Radiator

Many radiators are mounted at the front of the vehicle in the path of greatest airflow. The air carries heat away, cooling the liquid before it returns to absorb more heat from the engine.
Where a radiator is mounted also depends on space - how the engine is mounted. A header tank can be mounted away from the radiator, where it provides a coolant supply, stored above the engine. It can be made of sheet metal, or hardened plastic.
The radiator has 2 tanks and a core.
The materials used in the radiator must be good heat conductors like brass or copper. Brass and copper are often used for tanks, combined with a copper core.
Modern vehicles often use plastic tanks combined with an aluminium core. This saves weight but still provides good heat transfer.
The core consists of a number of tubes that carry coolant between the 2 tanks. The tubes can be in a vertical downflow pattern, or a horizontal crossflow pattern.
A crossflow radiator fits more easily under a steeply sloped bonnet.
In the core, small, thin, cooling fins are in contact with the tubes. The shape of the fins increases the surface area exposed to the air.
Where coolant touches tube walls, and where the tubes touch the fins, heat is removed from the coolant by conduction, then by radiation and convection at the surface of the fins. Air rushing by carries the heat away.
Liquid emerges cooler at the bottom of the radiator. It travels through the lower radiator hose to the water pump inlet, then through the engine again.

Engine Cooling : Basic cooling system components

• Radiator
• Thermostat & Housing
• Water Pump
• Cooling Fan
• Radiator Hoses
• Heater Hoses

Basic cooling system components

Cooling system components

The primary components in a vehicle cooling system are:

Radiator

The radiator is located in a convenient position under the hood of the vehicle. Its actual location under the hood depends on the engine configuration, available space and the shape or line of the hood itself.
The radiator consists of top and bottom tanks, and a core.
The radiator core allows the coolant to pass through it in either a vertical down or horizontal cross flow direction. In addition, the radiator core serves as a good conductor of heat away from the engine.

Engine Cooling : Cooling systems

• Air cooling
• Liquid cooling
• Rotary engine cooling system

Air cooling

Air-cooling is common on smaller internal combustion engines. They may be small but they still generate a lot of heat.
It’s the air that does the work of keeping them cool, so an air-cooling system is usually simple. That’s useful on an engine where weight is important.
And it works best on the engine that’s exposed to a high airflow.
Almost all motorcycles used to be air-cooled but modern motorcycles are larger and more complex, and some are now liquid-cooled.
Some engines use what are called cooling fins. Their design makes the exposed surface area as large as possible, which allows more heat energy to radiate away, and be carried off in convection currents in the air.
More air flows over the fins and more heat is carried away.
For a vehicle moving at speed, airflow over the engine is high.
At low speeds or during idling, heat builds up. Then the engine can use some help.
Air should always be able to flow over the engine effectively.
One way to remove heat is to use a fan, with shrouds and ducts to direct air to the cylinders.
There are many places to mount a fan and many ways to drive it. For instance, in some engines it’s on the flywheel, driven by fan-belts off the crankshaft.

Engine Cooling : Cooling fundamentals

• Cooling systems
• Heat transfer
• Vehicle coolant

Cooling systems

Combustion of the air-fuel mixture in the cylinders generates heat which produces high pressure, to force the piston down in the power stroke. Not all of this heat can be converted into useful work on the piston, and it must be removed to prevent seizure of moving parts. This is the role of the cooling system. Most engines are liquid-cooled.
A liquid-cooled system uses coolant - a fluid that contains special chemicals mixed with water. Coolant flows through passages in the engine, and through a radiator. The radiator accepts hot coolant from the engine, and lowers its temperature. Air flowing around, and through the radiator takes heat from the coolant. The lower-temperature coolant is returned to the engine through a pump.
Air cooling is common on smaller internal combustion engines. Some engines use cooling fins. Their design makes the exposed surface area as large as possible, which allows more heat energy to radiate away, and be carried off in convection currents in the air. Some engines also use a fan to direct air over the fins.