Cooling System

1
Cooling System Functions
2
Cooling System

• Two types
• Air Cooled
• Liquid Cooled

3
Air Cooled Engines

• Advantage
• Low production cost
• Disadvantage
• Vehicle motion is required to keep cool

4
Air cooled Engines

• Finned cylinders
• Why
• Creates more surface area to transfer heat away
  from the engine
• Two stroke engines create more heat because they
  fire on every revolution
• Fan
• Not used on all engines
• Creates air flow past cylinders to transfer heat
• Allows engines to run while standing still

5
Functions of Coolant

• Functions of coolant
• Dissipate heat
• Prevent rust and corrosion
• Lubricates the water pump
• Prevent Freezing

6
Corrosion Protection
7
Liquid Cooled Engines

• Advantages
• More consistent operating temperature
• More precise engine clearances

8
Remove Engine Heat

• Combustion can reach 4500 ºF
• This is hot enough to melt metal parts
• Cooling system removes excess heat

9
Maintain Operating Temperature

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

10
Cooling System
11
Liquid Cooling

• Heat is transferred to cylinder wall, into
  coolant and carried away

12
Types of Coolant

• Green
• Ethylene glycol based coolant
• Invented in 1926
• Toxic
• Two ounces of ethylene glycol antifreeze can kill
  a dog, one teaspoon can be lethal to a cat, and
  two tablespoons can be hazardous to children.

13
Types of Coolant

• Red
• Dexcool
• propylene glycol based
• Non-toxic at low levels
• Protects aluminum components
• Prevents cavitation
• Prevents corrosion and build up that destroys
  parts

14
Coolant Types

• Yellow
• Used by Ford
• Blue
• Used by Honda

15
Coolant Types

• Global
• Neon Green in color
• Safe to mix with any other color
• For More info see
• http//www.peakantifreeze.com/aboutus.html

16
Coolant

• Lowers coolant freezing point to about -34 ºF
  (-37 ºC)

17
Impeller Pump

• Coolant is thrown outward by centrifugal force,
  producing suction in the center of the pump
  housing

18
Water Pump Cutaway

• Seal leakage will drip from vent hole

19
Visual Inspection

• Watch for leakage from bleed holes

20
Visual Inspection

• Pump shaft should not wiggle or leak

21
Radiator and Heater Hoses
22
Radiator Hoses

• Two basic types of radiator hoses

23
Common Hose Problems
24
Hose Clamps

• Three basic types of hose clamps

25
Hose Condition
26
Radiator

• Transfers coolant heat to the outside air

27
Radiator Types
28
Transmission Oil Cooler

• Small tank inside one of theradiator tanks

29
Leaking Radiator
30
Radiator Cap Pressure Valve

• Spring-loaded disk
• Normally, water boils at 212 ºF
• For each pound of pressure increase, boiling
  point goes up about 3 ºF
• Typical pressure
• 1216 psi
• raises boiling point to 250260 ºF

31
Pressure Cap Operation

• Hot engine

32
Pressure Cap Operation

• Cold engine

33
New Style Overflow Tank
34
Flex Fan

• High rpm cause blades to flex, reducing blowing
  action

35
Thermostatic Fan Clutch

• Bimetal spring controls clutching action
• Coldclutch slips
• Hotclutch locks

36
Electric Fans

• Turned on by
• Temp Sending Unit
• PCM
• Most common fan found today

37
Thermostat

• A temperature-sensitive valve

38
Thermostat Operation
39
Bypass Valve
40
Chapter 40
Cooling System Testing, Maintenance, and Repair
41
Coolant Protection Level

• Find what type of coolant is in system
• Test the Protection level (-20 to -35F)
• Test PH level
• Check overall condition of coolant

42
PH Test

• Check coolant for DC volts
• Acidic coolant acts as a battery acid
• If above 0.5 volts than coolant is acidic

43
Dirty Antifreeze
44
Check for leaks

• Hook up pressure tester
• Apply 2-3 lbs more pressure than cap will hold
• Watch for pressure to drop
• Look for leaks

45
Pressure Testing a Radiator Cap
46
Coolant Flush

• Removes rust and scale
• Should be done every other year

47
Drain Radiator
48
Cooling System Problems

• Mineral deposits in water jackets can prevent
  proper heat transfer

49
Cooling System Problems

• A cracked part or blown gasket can allow coolant
  to leak into the engine oil

50
Oil and Water Mix
51
Causes of Overheating

• Low coolant level
• Rust or scale accumulation in water jacket
• Stuck thermostat
• Retarded ignition
• Loose fan belt
• Bad water pump or collapsed lower hose
• Missing fan shroud or fan problems

52
Causes of Overcooling

• Stuck thermostat (open)
• Locked fan clutch
• Shorted fan switch

53
Thermostat Service

• A stuck thermostat can cause engine overheating
  or overcooling
• Stuck openovercooling
• loss of efficiency, power, mileage
• high emissions
• Stuck closedoverheating
• engine damage

54
Bleeding the Cooling System
55
Belt Types

• V- Belt
• Seldom used today
• Serpentine Belt
• Most common
• Runs multiple pulleys

56
Belt Facts

• Serpentine Belt
• 1979 Ford Mustang the first to use
• Saved 3" to the front of the car
• Saved 28 lb in total weight of the car
• Cam about because of oil crisis

57
Belt Inspection

• Check tension
• Check for cracks
• 3 cracks/inch 80 belt life gone
• Check for wear

58
Belt Test

• Belt Squeal
• Spray water on the belt
• If the squeal goes away
• Misalignment Problem
• If the squeal continues
• Tension Problem

59
Automatic Tensioner

• Spring tensioners
• Along with the tension spring there is also a
  dampener which acts like a shock absorber
• To inspect the tensioner
• Look for rust bleed
• Spring is cracked or broken
• Cracked arm
• Tensioners failing at 50 to 60 thousand miles