1. Chapter 11
Cooling Systems
page 191

2. Cooling Systems Types
Air cooling
Liquid Cooling
Mixture Air/Liquid

3. Principles of Engine Cooling
Efficiency and life of engine
Burned gasses 3600 F
Loss of heat through cylinder walls
1200 F to 350 F
100 F by outer fins

4. COOLING SYSTEMS
Heat Energy From Combustion
1. Cooling and Lubrication systems 33%
2. Exhaust system 33%
Engine power 25%
Frictional loss 5%

5. How Air Cooling Works heat passes through cylinder wall
air passes by fins
guided by baffles
Conduction – through a material material
Convection – solid to gas transfer
Radiation – gives off heat

6. Parts of an Air Cooled system
Fly Wheel
Shrouds
Fins

7. How Exhaust Cooling Works
1/3 heat lost through exhaust (muffler) 1200 F
Blocked muffler
Broken muffler

8. How Water Cooling Works
Passage surrounds cylinder (water jacket)
No fins
water/antifreeze mixture
protects freezing
raise boiling point
prevent corrosion

9. Parts of the Liquid Cooled System
Radiator
Water pump
Water Jacket
Hoses
Fan
Shroud
Belt
Thermostat

10. Radiator
Tubes
Fins
Transfers heat
coolant >air

11. Radiators Caries water through tubes Air travels through fins
Together make RADIATIOR CORE
Cross flow & Down flow

12. Water Pumps Moves coolant Boat at lower end of motor
Driven by crankshaft
Types
sliding vane
rotor
plunger
vari-volume

13. Radiator Cap
Pressurize
Pascal’s Law
1 psi = 3 F

14. Observing Thermostat Operation
Opens at preset temp.
Rating stamped on thermostat
Holds coolant in block
Opens to cool

15. Outboard Water Circulation Systems
Pressure-vacuum water flow system
propeller causes pressure & vacuum
Centrifugal force
no moving parts (propeller)

16. How Oil Cooling Works Oil collects dirt and particles
Removes heat (5%)