aurt202166a repair cooling systems © commonwealth of australia 2011 aurt202166a repair cooling...

AURT202166A REPAIR COOLING SYSTEMS

© Commonwealth of Australia 2011 AURT202166A Repair Cooling Systems

AURT202166A

Repair cooling systems

AUR30405 CERTIFICATE III IN AUTOMOTIVE MECHANICAL TECHNOLOGY



Types of cooling systems

All internal combustion vehicles have a cooling system.

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Why have a cooling system?

• Remove excess heat so the engine temperature doesn’t go too high.

• Maintain a minimum engine operating temperature.

• Give a rapid engine warm up.

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Heat Transfer

Heat can be transferred in three ways:

1. Conduction- heat transfers through the metal parts

2. Convection- heat transfers through the coolant

3. Radiation- heat transfers from the metal parts to the outside air.

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Cooling system operation

• Extremely high temperatures are created inside the engine.

• The heat is transferred into the coolant.

• The coolant is pumped through the radiator core and fins.

• Air passing through the radiator fins reduces the coolant temperature.



Cooling system construction

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Expansion bottle Hose

Radiator cap

Temp sender

Heater tap

Cabin heater core

Cylinder Head gasket

Welshplug

Heater hose

Drain plug Automatic transmission cooler lineFan belt

Hose

Fan



Engine coolant safety

Coolant is a mixture of water and chemicals and it is poisonous.

•Wear personal protective equipment.

•Store or recycle used coolant safely.

•Don’t pour down drains.

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Radiator cap safety

1. Allow the engine to cool down.2. Place a thick rag over the cap.3. Turn the cap anti-clockwise – 1/4 of a turn.4. Press down cap and remove.

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External leaks

External coolant leaks can be in:•coolant hoses•radiator•welsh plugs•radiator cap.

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Use a pressure tester to find external cooling system leaks. Always check operating instructions before use.



Internal leaks

Internal coolant leaks can be in:

• cylinder head gasket• cracked cylinder head• cracked cylinder

block.

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For an accurate diagnosis use a CO2 leak detector to help identify internal cooling system faults. Always consult CO2 leak detector operating instructions before use.

Head gasket leaking coolant



Cooling system checklist

Complete the inspection checklist to ensure:

• you identify all cooling system faults

• you make accurate recommendations and quotes.

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Reverse FlushingWhat is reverse flushing?

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• Forcing water through the cooling system in the opposite direction to clean the cooling system.

Why do we reverse flush?

• To remove rust and scale from the cooling system

• To remove the old coolant to avoid cross contamination.

Water out

Water in



Welsh plugs

• Designed to seal the casting holes.

• Made from mild steel or brass.

• Most vehicles use the cup welsh plug.

• Can leak coolant if cooling system is neglected.

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Water pumpPumps the coolant through the engine and radiator.Repair or replace when:• noisy• leaking coolant• causing engine to overheat.

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Thermostat

• A temperature sensitive control valve.

• Ensures engine reaches operating temperature quickly.

• Controls the operating temperature of the cooling system.

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Thermostat testing

Test the thermostat to check:• opening temperature• correct operation.

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Cooling fans

Test for:

• Correct operation

• Noisy fan motor

• Damaged fan blades.

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Radiator and hoses

May need removing to:

• Repair radiator leaks or blockages

• Replace the water pump

• Replace engine or components

•Service cooling hoses.

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Radiator and hoses

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© Commonwealth of Australia 2011ISBN: 978-1-876838-58-4

This document is available under a “Free for Education” licence for educational purposes – see http://www.aesharenet.com.au/FfE2 for details.This work is copyright. You may download, display, print and reproduce this material in whole or in part or in modified form (retaining this notice) for your personal, non-commercial use or use within your organisation. If you use, display, or reproduce this material or a modified form of it in whole or in part within your organisation you must include the following words in a prominent location within the material in font not less than size 12: ‘The views expressed in this publication do not necessarily represent the view of the Minister for Education or the Australian Government. The Australian Government does not give any warranty nor accept any liability in relation to the contents of this work’. Apart from any use as permitted under the Copyright Act 1968, all other rights are reserved. Requests and inquiries concerning reproduction and rights should be addressed to the Commonwealth Copyright Administration, Attorney General’s Department, Robert Garran Offices, National Circuit, Barton ACT 2600 or posted at http://www.ag.gov.au/cca.

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The views expressed in this publication do not necessarily represent the view of the Minister for Education or the Australian Government. The Australian Government does not give any warranty nor accept any liability in relation to the contents of this work.

aurt202166a repair cooling systems © commonwealth of australia 2011 aurt202166a repair cooling...

Documents

cooling system operation

external cooling system

coolant slide

internal cooling system

coolant temperature

used coolant

radiator core

radiator fins