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Modern Automotive

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The water pump forces coolant through the engine water jackets ... 120-volt heating element mounted in the block water jacket. Common on diesel engines ... – PowerPoint PPT presentation

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Title: Modern Automotive


1
PowerPoint for
Modern Automotive Technology
by Russell Krick
2
Chapter 39
Cooling System Fundamentals
3
Contents
  • Cooling system functions
  • Cooling system operation
  • Cooling system types
  • Basic cooling system
  • Closed and open cooling systems
  • Cooling system instrumentation
  • Antifreeze
  • Block heater

4
Cooling System Functions
5
Remove Engine Heat
  • Combustion can reach 4500ºF (2500ºC)
  • This is hot enough to melt metal parts
  • The cooling system removes excess heat

6
Maintain Operating Temperature
  • 180ºF to 210ºF (80ºC to 100ºC)
  • Ensures that clearances are correct
  • when an engine warms to operating temperature,
    parts expand
  • Ensures proper combustion, minimum emissions, and
    maximum performance

7
Reach Operating Temperature Quickly
  • This minimizes several conditions
  • poor combustion (poor fuel vaporization)
  • part wear
  • oil contamination
  • reduced fuel economy
  • increased emissions

8
Heater Operation
  • The cooling system circulates coolant to the
    vehicles heater
  • Engine heat is used to warm the passenger
    compartment

9
Cooling System
10
Cooling System Operation
  • The water pump forces coolant through the engine
    water jackets
  • The pump is belt or gear driven off the crankshaft

11
Cold Engine Operation
  • The thermostat is closed
  • The coolant circulates inside the engine
  • The engine warms quickly

12
Hot Engine Operation
  • At operating temperature, the thermostat opens
  • Heated coolant then flows through the radiator
  • Excess heat is transferred from the coolant to
    the air flowing through the radiator

13
Cooling System Types
  • Two common types
  • air cooling
  • liquid cooling

14
Air Cooling Systems
  • Large cylinder cooling fins and outside air
    remove excess heat
  • The cooling fins increase the surface area of the
    metal around the cylinder
  • This allows enough heat to transfer to the
    outside air
  • Plastic or metal shrouds direct air over the
    cylinder fins

15
Liquid Cooling Systems
  • Circulate coolant through the water jackets
  • Combustion heat is transferred to the coolant
  • The cooling system carries it out of the engine

16
Liquid Cooling Advantages
  • Precise temperature control
  • Less temperature variation
  • Reduced emissions
  • Improved heater operation

17
Air Cooling versus Liquid Cooling
18
Liquid Cooling
  • Heat is transferred to cylinder wall and then
    into the coolant, where it is carried away

19
Conventional Coolant Flow
  • Hot coolant flows from the cylinder head to the
    radiator
  • After being cooled in the radiator, the coolant
    flows back into the engine block

20
Reverse Flow Cooling
  • Cool coolant enters the head and hot coolant
    exits the block to return to the radiator
  • Helps keep a more uniform temperature throughout
    the engine
  • Found on high-performance engines

21
Basic Cooling System
  • Components
  • water pump
  • radiator hoses
  • radiator
  • fan
  • thermostat

22
Water Pump
  • A ribbed belt powers this pump

Crankpulley
Impeller
Ribbedbelt
Water pump pulley
23
Impeller Pump
  • Coolant is thrown outward by centrifugal force,
    producing suction in the center of the pump
    housing

24
Water Pump Cutaway
  • Seal leakage will drip from the vent hole

25
Coolant Flow
26
Coolant Flow (Conventional)
  • Coolant flows out of the radiator, through the
    lower hose, into the pump
  • It then flows through the pump, around the
    cylinders, through the heads, up through the
    thermostat, and back into the radiator

27
Hoses
  • Radiator hoses
  • carry coolant between the engine water jackets
    and the radiator
  • the lower hose is exposed to water pump suction,
    so a spring may needed to prevent collapse
  • Heater hoses
  • carry hot coolant to the heater core
  • smaller diameter than radiator hoses

28
Radiator and Heater Hoses
29
Radiator Hoses
  • Two basic types of radiator hoses

30
Hose Clamps
  • Three basic types of hose clamps

31
Radiator
  • Transfers coolant heat to the outside air

32
Radiator Types
33
Transmission Oil Cooler
  • Often placed in the radiator on cars with
    automatic transmissions
  • Prevents the transmission fluid from overheating

34
Transmission Oil Cooler
  • Small tank inside one of theradiator tanks

35
Oil Cooler System
36
Radiator and A/C Condenser
  • The condenser is usually mounted in front of the
    radiator
  • in this arrangement, heat from the condenser
    flows through the radiator, reducing efficiency
  • Side-by-side mounting is sometimes used

37
Radiator and A/C Condenser
  • This vehicle has side-by-side mounting

38
Radiator Cap
  • Seals the radiator
  • Pressurizes the system
  • Relieves excess pressure
  • Allows coolant flow between the radiator and the
    coolant reservoir

39
Radiator Cap
40
Radiator Cap Pressure Valve
  • Spring-loaded disk
  • Normally, water boils at 212ºF (100ºC)
  • For each pound of pressure increase, the boiling
    point goes up about 3ºF (1.7ºC)
  • Typical pressure
  • 1216 psi (83110 kPa)
  • raises the boiling point to 250260ºF (121127ºC)

41
Radiator CapVacuum Valve
  • Opens to allow flow back into the radiator when
    the coolant temperature drops

42
Closed and Open Cooling Systems
  • Closed cooling system
  • uses an expansion tank
  • overflow tube is routed into reservoir tank
  • Open cooling system
  • allows excess coolant to leak onto the ground

43
Pressure Cap Operation
  • Hot engine

44
Pressure Cap Operation
  • Cold engine

45
Cooling System Fans
  • Pull air through the core of the radiator
  • Increase the volume of air flowing through the
    radiator
  • Driven by fan belt or electric motor

46
Flex Fan
  • High engine speed causes the blades to flex,
    reducing the blowing action

47
Fluid Coupling Fan Clutch
  • Filled withsilicone-based oil
  • The clutch slips at higher rpm

48
Thermostatic Fan Clutch
  • Bimetal spring controls clutching action
  • coldclutch slips
  • hotclutch locks

49
Electric Cooling Fans
  • An electric motor and a thermostatic switch
    provide cooling
  • Common on transverse-mounted engines
  • Save energy and increase cooling efficiency
  • Fans only function when needed

50
Electric Fan Operation
  • Cold engine

51
Electric Fan Operation
  • Hot engine

52
PCM-Controlled Fans
  • When cold, the ECM does not energize the fan
    relays
  • After warm-up, the ECM feeds current to the fan
    relay coils, closing the relay contacts
  • High current flows to fans

53
PCM-Controlled Fans
54
Radiator Shroud
  • Ensures that the fan pulls air through the
    radiator core

55
Thermostat
  • Senses the coolant temperature and controls
    coolant flow through the radiator
  • Reduces coolant flow in a cold engine
  • Increases coolant flow in a hot engine

56
Thermostat
  • A temperature-sensitive valve

57
Thermostat Operation
  • Cold engine
  • wax-filled pellet has contracted
  • spring holds valve closed
  • Hot engine
  • when heated, pellet expands
  • spring tension is overcome
  • valve opens

58
Thermostat Operation
  • A. Cold engine
  • B. Hot engine

59
Thermostat Operation
  • Cold engine

60
Thermostat Operation
  • Hot engine

61
Bypass Valve
  • Permits coolant circulation through the engine
    when the thermostatis closed

62
Bypass Thermostat
  • Blocks off the bypass at operating temperature

Impeller
Flow toradiator
Water pumpdrive pulley
Bypass spring
Water pumphousing
Bypassflow
Thermostat
Mainspring
Main flow
63
Cooling System Instrumentation
  • Two common types
  • temperature warning light
  • engine temperature gauge

64
Temperature Warning Light
  • When the coolant becomes too hot, a temperature
    sending unit (switch) in the block closes,
    completing a light circuit
  • The warning light glows

65
Warning Light Circuit
66
Engine Temperature Gauge
  • Shows the exact operating temperature
  • Components
  • gauge
  • variable resistance sending unit

67
Engine Temperature Gauge Operation
  • When cold, the sending unit has a high resistance
  • Current flow through the gauge is low
  • The gauge reads cold
  • When hot, the sending unit resistance lowers
  • Current flow through the gauge increases, the
    needle deflects to the right

68
Antifreeze
  • Composed of ethylene glycol mixed with water
  • Prevents winter freeze-up
  • Prevents rust and corrosion
  • Lubricates the water pump
  • Cools the engine

69
Corrosion Protection
70
Antifreeze/Water Mixture
  • Lowers the coolant freezing point to about 34
    ºF (37 ºC)

71
Block Heater
  • Aids engine starting in cold weather
  • 120-volt heating element mounted in the block
    water jacket
  • Common on diesel engines

72
Block Heater Installation
73
Engine and Cooling System
74
Engine and Cooling System
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