1. THE COOLING SYSTEM

2. Purpose
• To regulate the engines internal
temperature
• To remove excess heat from the engine
• To provide heat to the passenger
compartment

3. The Water Pump
• Centrifugal-type,
rotates faster than
crank, up to
10,000 gal. per
hour
• Pulley driven, belt,
chain drive or
direct drive

4. The Cooling Fan
• Provides air flow
with vehicle stopped
• Provides increased
air flow at low RPM
or vehicle speeds
• Belt driven or
Electric

5. Belt Driven Cooling Fan Clutch
• Limits actual fan speed
no more than 2000 rpm
• Engaged at low speeds
• Disengaged at high
speeds
• Thermostatic (temp.
sensitive)

6. Flex Blade Fan
• Fan blades
flatten out at
high
speeds,
reducing
noise,
increasing
horse power

7. Electric Cooling Fan
• Electric – 12v DC motor
driven fan
• Controlled in several ways
– Engine coolant temp (ECT)
switch
– A/C select switch
– PCM controlled based on
various inputs
• Fan turns on/off at specific
temps.

8. Electro-Viscous Fan Clutch
• PCM Controlled fan
speed
• Sensors monitored to
control speed:
– ECT, A/C request,
VSS, IAT, Trans Fluid
Temp, AAT
• Solenoid controls fluid
flow, regulating fan
speed
• Internal hall effect sensor
monitors fan speed

9. The Radiator
• Transfers heat from coolant to the
atmosphere
• Two types – Vertical & cross flow
• Aluminum, brass, copper core; brass,
copper or plastic tanks
• Air movement through radiator created
by a mechanical fan or by vehicle
movement (ram air) dissipates heat

10. How a Radiator Works

11. Radiator Pressure Cap
• Regulates pressure in the cooling
system
• Rated in psi – always replace with same
rating
• Pressure valve – allows liquid or vapor
to escape
• Vacuum valve – as system cools,
coolant can reenter the system

13. The Thermostat
• Regulates engine coolant temperature
• Rated in degrees – 195 degrees most
common
• Solid Expansion design – wax pellet
expands as temp increases, valve
begins opening at rating & is completely
open within 20 degrees

15. Coolant
• Provides freeze & boil over protection,
corrosion prevention & good heat
transfer
• Ethylene Glycol based – recommended
50/50 mixture with water, poisonous
• Dex-Cool – used by GM, 5 year
150,000 mile protection, doesn’t contain
silicate & phosphate additives

16. The Heater Core
• Small size radiator located in the dash,
coolant circulates through it. A blower
motor passes fresh air over it, heat
transfers to the cooler air and into the
cabin
• Many vans & SUV have rear heating
units

18. OLD
NEW

19. Overvie
w

20. SUBMITTED BY:ASHU RANJAN
ROLL NO