Modern Auto Tech Study Guide Chapters 39 & 40 Pages Cooling Systems 43 Points. Automotive Service

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1 Modern Auto Tech Study Guide Chapters 39 & 40 Pages Cooling Systems 43 Points

2 1. The cooling system must control the temperature of the engine for low emissions and maximum efficiency. This will also result in the best fuel economy and performance. Operating Cooling Heating

3 2. The coolant operating temperature is normally between 180º and 210º degrees Fahrenheit.

4 3. Engine coolant is circulated through the to warm the PASSENGER compartment. Heater Core Skater Core Emitter Core

5 4. The is a belt driven, impeller that circulates coolant through the water JACKETS.

6 5. When the coolant is hot enough to cause the to open it flows out of the engine and into the radiator where its heat is transferred to the surrounding (ambient) air. Thermostat Rheostat Hemostat

work to direct air flow from a fan through the fins.

7 6. Air cooling systems are characterized by cooling on the side of the cylinders as well as shrouds and duct work to direct air flow from a fan through the fins. Convection carries heat to the ambient air. Bins Fins Tins

8 7. Liquid cooling systems offer more precise of engine operating temperature with less variation. This reduces exhaust emissions, increases mpg & performance, and improves heater operation. Cooling Heating Control

9 8. The transfers heat from the coolant to the surrounding outside air. Heater Core Radiator Condenser

10 9. The job of the is to draw air through the radiator, especially when the car isn t moving forward. Fan Shroud Cap

11 10. Radiator may be molded or flexible & may have an internal SPRING to prevent collapsing. Caps Shrouds Hoses

12 11. An automatic TRANSMISSION FLUID cooler is located inside of the radiator side or bottom tank.

13 12. Radiators are either DOWNFLOW (vertical) or CROSSFLOW (horizontal) design.

14 13. Radiator tanks are made of either or. Plastic tanks are used exclusively with aluminum core radiators. Ceramic or Plastic Metal or Plastic Stone or Plastic

15 14. The air conditioning may be mounted along side of or in front of the radiator. Accumulator Condenser Evaporator

16 15. The radiator seals the filler neck, pressurizes the system to raise the boiling point, relieves excess pressure to protect against system damage, & allows coolant exchange between the recovery reservoir. Cap Shroud Fan

17 16. For every 1# of pressure that a radiator cap holds on a system, coolant boil point is raised Fº. (technically 3.25 ) 200 F 50 F 3 F

A malfunctioning vacuum valve would cause radiator

18 17. The radiator cap valve allows coolant return to the system when the engine is cooled off. A malfunctioning vacuum valve would cause radiator hoses and possibly tanks to collapse from vacuum. Vacuum Pressure Relief

19 18. The cooling system utilizes the cap and recovery reservoir to maintain proper coolant levels in the engine at all times by burping out hot coolant & later siphoning back in cooled off coolant. Closed Open Ajar

19. To conserve horsepower, radiator fans

20 19. To conserve horsepower, radiator fans have either thermostatic or are operated. Electric fans have the on time of their motors controlled by sensors, relays, and the PCM. Clutches or are Electrically Clutches or are Mechanically Clutches or are Hydraulically

21 20. The radiator acts like a funnel to direct the air through the area where the fan is situated. Cover Shroud Cap

Most thermostats are set to open between 180 and 195 Fº.

22 21.The thermostat works with a spring loaded, filled pellet that senses coolant temperature. Most thermostats are set to open between 180 and 195 Fº. (A thermostat is closed when the engine coolant is cold.) Wax Mercury Plastic

23 22. A thermostat valve is used to maintain circulation of the coolant through the block, heads, heater core when the engine is not yet warm. (A stuck open thermostat lowers heater output & overcools the engine) Over Pass By Pass Under Pass

24 23. Antifreeze is usually a chemical mixture called ETHYLENE GLYCOL, but propylene glycol mixtures are now becoming popular because they are less toxic. (Dexcool is orange in color)

26 24. A 50/50 mixture of antifreeze and water will prevent to at least 34 degrees, will prevent rust and corrosion, lubricates the water pump and will cool the engine more effectively than water alone since the boiling point of a 50% mixture is 265 degrees Fahrenheit. Freezing Pressure Relief

30 25. Engine heaters are used in extremely cold weather to warm the coolant, the block, and also the oil so that the engine cranks easier. (crankshaft counterweights move easier through a thinner, warmer oil) Crock Cloak Block

32 ~~~ 26. Coolant leaks can be located by performing a cooling system test. Pressure Vacuum Flushing

33 27. Suspect an engine that is consuming coolant with no external leaks of having an leak like a cracked block, cracked cylinder head, or a blown head gasket. Internal Pressure Relief

34 28. The presence of exhaust gas (HC & CO) above the coolant level in the radiator can indicate a blown head gasket, a cracked block, or a cracked cylinder head.

35 29. When water, antifreeze, and oil mix, the solution turns MILKY WHITE in color.

36 30. Stuck thermostats, slipping belts, and clogged radiators can cause overheating.

37 31. Stuck thermostats, locked on fan clutches, or shorted fan switches can cause overcooling.

38 32. Some cooling system have a BLEEDER screw to let trapped air escape when refilling the system.

a chemical source of voltage in the cooling system.

39 33. Coolant should be FLUSHED at regular intervals. Old antifreeze becomes ACIDIC and can actually generate a chemical source of voltage in the cooling system. Over.5 volts indicates high acidity.

$a refractometer can also be used to$

40 34. A coolant or special coolant test strips are used to measure coolant freeze point. A more sophisticated tool known as a refractometer can also be used to determine freeze point. Tachometer Hydrometer Multimeter

Auto Service Test Review. For the Most Effective Personal Review, Match the Following Questions to the On Line Study Guide Multimedia

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