aurt202166a repair cooling systems © commonwealth of australia 2011 aurt202166a repair cooling...
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AURT202166A REPAIR COOLING SYSTEMS
© Commonwealth of Australia 2011 AURT202166A Repair Cooling Systems
AURT202166A
Repair cooling systems
AUR30405 CERTIFICATE III IN AUTOMOTIVE MECHANICAL TECHNOLOGY
AURT202166A REPAIR COOLING SYSTEMS
© Commonwealth of Australia 2011 AURT202166A Repair Cooling Systems
Types of cooling systems
All internal combustion vehicles have a cooling system.
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AURT202166A REPAIR COOLING SYSTEMS
© Commonwealth of Australia 2011 AURT202166A Repair Cooling Systems
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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AURT202166A REPAIR COOLING SYSTEMS
© Commonwealth of Australia 2011 AURT202166A Repair Cooling Systems
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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AURT202166A REPAIR COOLING SYSTEMS
© Commonwealth of Australia 2011 AURT202166A Repair Cooling Systems
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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.
AURT202166A REPAIR COOLING SYSTEMS
© Commonwealth of Australia 2011 AURT202166A Repair Cooling Systems
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
AURT202166A REPAIR COOLING SYSTEMS
© Commonwealth of Australia 2011 AURT202166A Repair Cooling Systems
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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AURT202166A REPAIR COOLING SYSTEMS
© Commonwealth of Australia 2011 AURT202166A Repair Cooling Systems
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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AURT202166A REPAIR COOLING SYSTEMS
© Commonwealth of Australia 2011 AURT202166A Repair Cooling Systems
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.
AURT202166A REPAIR COOLING SYSTEMS
© Commonwealth of Australia 2011 AURT202166A Repair Cooling Systems
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
AURT202166A REPAIR COOLING SYSTEMS
© Commonwealth of Australia 2011 AURT202166A Repair Cooling Systems
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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AURT202166A REPAIR COOLING SYSTEMS
© Commonwealth of Australia 2011 AURT202166A Repair Cooling Systems
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
AURT202166A REPAIR COOLING SYSTEMS
© Commonwealth of Australia 2011 AURT202166A Repair Cooling Systems
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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AURT202166A REPAIR COOLING SYSTEMS
© Commonwealth of Australia 2011 AURT202166A Repair Cooling Systems
Water pumpPumps the coolant through the engine and radiator.Repair or replace when:• noisy• leaking coolant• causing engine to overheat.
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AURT202166A REPAIR COOLING SYSTEMS
© Commonwealth of Australia 2011 AURT202166A Repair Cooling Systems
Thermostat
• A temperature sensitive control valve.
• Ensures engine reaches operating temperature quickly.
• Controls the operating temperature of the cooling system.
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AURT202166A REPAIR COOLING SYSTEMS
© Commonwealth of Australia 2011 AURT202166A Repair Cooling Systems
Thermostat testing
Test the thermostat to check:• opening temperature• correct operation.
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AURT202166A REPAIR COOLING SYSTEMS
© Commonwealth of Australia 2011 AURT202166A Repair Cooling Systems
Cooling fans
Test for:
• Correct operation
• Noisy fan motor
• Damaged fan blades.
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AURT202166A REPAIR COOLING SYSTEMS
© Commonwealth of Australia 2011 AURT202166A Repair Cooling Systems
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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AURT202166A REPAIR COOLING SYSTEMS
© Commonwealth of Australia 2011 AURT202166A Repair Cooling Systems
Radiator and hoses
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AURT202166A REPAIR COOLING SYSTEMS
© Commonwealth of Australia 2011 AURT202166A Repair Cooling Systems
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© Commonwealth of Australia 2011ISBN: 978-1-876838-58-4
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