Cooling System Fundamentals

1. Cooling System Fundamentals

2. Contents • Cooling system functions • Cooling system operation • Cooling system types • Basic cooling system • Closed and open cooling systems • Cooling system instrumentation • Antifreeze • Block heater

3. Cooling System Functions

4. Cooling System Functions • Helps Engine Reach Operating Temperature Quickly • Maintains Constant Engine Operating Temperature • Removes Excess Engine Heat • Provides Heat For Warming the Passenger Area

5. Helps Engine Reach Operating Temperature Quickly • Advantages of Rapid Engine Warm-up: • Improved combustion (better fuel vaporization) • Reduced part wear • Less oil contamination • Increased fuel economy • Reduced emissions

6. Advantages of Maintaining aProper Operating Temperature • Ensures Proper Combustion • Minimum Emissions • Maximum Performance • Maintains Optimum Fuel Economy

7. Maintains Constant Operating Temperature • Thermostat opens and closes to Maintain Temp • 160 ºF to 195 ºF(Depending on thermostat) • When an engine warms to operating temperature parts expand and rapid warm-up reduces part wear • Ensures that clearances are correct

8. Removes Excess Engine Heat • On Modern Vehicles, Typical Combustion Temperatures can reach 4500 ºF (2500 ºC) • This is hot enough to melt metal parts • Cooling system removes excess heat which can cause major engine damage!

9. Air-cooled Engine • This air-cooled engine has had the cooling fan and shrouding removed for better viewing. • The shrouding directs the air-flow around the cylinders

10. Cooling System Types • Two common types: air cooling liquid cooling Cooling Fan & Shrouding Removed for better view

11. Air Cooling Versus Liquid Cooling

12. Air Cooling Systems • Large cylinder cooling fins and outside air remove excess heat • Cooling fins increase the surface area of the metal around the cylinder • This allows enough heat transfer to the outside air • Plastic or metal shrouds duct air onto and around the cylinder fins

13. Liquid Cooling Systems • Circulate coolant through the water jackets • Combustion heat is transferred to the coolant • Cooling system carries it out of the engine • Hot coolant flows into the radiator where heat is removed • Cooled coolant flows back into engine to repeat this process

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

15. Liquid Cooling Heat is transferred to cylinder wall, into coolant and carried away

16. 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

17. 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

18. Basic Cooling System • Components: • Radiator • Radiator Hoses • Fan • Thermostat • Water Pump

19. Radiator Transfers coolant heat to the outside air

20. Vertical Flow Cross Flow Radiator Types

21. Radiator Hoses and Heater Hoses

22. Hoses • Radiator Hoses • Carry coolant between the engine water jackets and the radiator • Lower hose is exposed to water pump suction so a spring may prevent collapse • Heater Hoses • Carry hot coolant to the heater core • Smaller diameter than radiator hoses

23. Hose Clamps Three basic types of hose clamps

24. Radiator Hoses Two basic types of radiator hoses

25. Radiator Fan • Draws air through the radiator and cools off the hot coolant passing through it.

26. Thermostat • Maintains a constant engine temperature • Helps engine reach operating temperature quickly • Senses coolant temperature and controls coolant flow through the radiator • Reduces coolant flow on cold engine • Increases coolant flow on hot engine

27. Thermostat A temperature-sensitive valve

28. 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

29. Thermostat Operation A. Cold engine B. Hot engine

30. Thermostat Operation Cold engineHot engine

31. Crankpulley Impeller Ribbedbelt Water pump pulley Water Pump A ribbed belt powers this pump which pumps coolant throughout the engine.

32. Impeller Pump Coolant is thrown outward by centrifugal force, producing suction in the center of the pump housing. Straight impeller blades use less energy to operate.

33. Water Pump Cutaway Water Pump Parts

34. Vertical Flow Tanks on top and bottom Cross Flow Tanks on both sides Radiator Types

35. Transmission Oil Cooler • Often placed in the radiator on cars with automatic transmissions • Prevents transmission fluid from overheating

36. Transmission Oil Cooler Small tank inside one of theradiator tanks

37. Water pump housing -Iron or aluminum casting that forms the main body of the pump. Water pump impeller -Disk with fan-like blades, the impeller spins and produces pressure and flow. Water pump shaft -Steel shaft that transmits theturning force from the hub to the impeller. Water pump seal -Prevents coolant leakage between pump shaft and pump housing. Water pump bearing -Plain or ball-bearings that allow the pump shaft to spin freely in housing. Water pump gasket -Fits between the water pump andthe engine to prevent leakage. Water pump hub -Provides a mounting place for thebelt, pulley, and fan. Water Pump Parts

38. Radiator Hoses and Clamps • Radiator hoses –Carry coolant between the engine water jackets and the radiator. • Flexible hose –Has an accordion shape and can be bent to different angles. • Molded hose –Manufactured in a special shape, with bends to clear the cooling fan and other parts. • Heater hoses –Small-diameter hoses that carry coolant to the heater core. • Hose spring –Frequently used in the lower radiator hose to prevent the hose from collapsing. • Worm-drive hose clamps –Uses a worm gear that engages slots in the clamp strap to allow tightening around the hose. • Hose clamps –Hold the radiator hoses and heater hoses onto their fittings

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

40. Radiator Cap

41. Radiator CapVacuum Valve Opens to allow flow back into the radiator when the coolant temperature drops. Without this valve the coolant would not flow back into the radiator and the radiator would become low on coolant and the engine would overheat.

42. Radiator Cap Pressure Valve • Spring-loaded disk • Normally, water boils at 212 ºF (100 ºC) • For each pound of pressure increase, boiling point goes up about 3 ºF (1.6 ºC) • Typical pressure: • 12–16 psi • raises boiling point to 250–260 ºF (121–127 ºC)

43. 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

44. Pressure Cap Operation Hot engine Cold engine

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

46. Flex Fan High rpm cause blades to flex, reducing blowing action

47. Fluid Coupling Fan Clutch Filled withsilicone-based oil Slips at higher rpm

48. Thermostatic Fan Clutch • Bimetal spring controls clutching action • Cold—clutch slips • Hot—clutch locks

49. Electric Cooling Fans • Provide cooling with an electric motor and a thermostatic switch • Use A small direct current motor to operate the cooling fan • Common on transverse-mounted engines • Save energy and increase cooling efficiency • Fans only function when needed

50. Electric Fan Operation Cold engine Hot engine