73 terms

Engine Cool and Lubrication Systems

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What is the typical highest combustion temperature in a gasoline engine?
~4500 degrees F
What percentage of heat produced by an internal combustion engine passes out of the engine with the exhaust gases?
40-45%
In an air-cooled system, does the rate of cooling depend upon the heat conductivity of the metal used?
Yes, as well as the volume of the metal or its size (in cross-section)
Is the lubricating oil used in air-cooled systems generally of a higher of lower viscosity than that used in liquid-cooled system?
Higher
What are the principle components of an air-cooled system?
1. Fan
2. Shroud
3. Baffles
4. Fins
Do the air-cooled systems used on motocycles or on outboard engines require fans or shrouds?
No, since their own movement through the air causes sufficient airflow over the engines for adequate cooling to occur
What are the main components of the radiator in a liquid-cooled engine?
1. Core
2. Thanks
3. Filler Neck
4. Oil cooler
5. Petcock
What is the function of a radiator petcock?
To drain the coolant
How many fins per inch are normally designed into a tube-and-fun radiator for a vehicle WITH air-conditioning?
7 fins/inch
How many fins per inch are normally designed into a tube-and-fun radiator for a vehicle WITHOUT air-conditioning?
5 fins/inch
Where are the coolant thanks positioned on a crossflow radiator?
The tanks are on the sides of the core, and the core tubes are arranged for horizontal coolant flow
Where does the upper radiator hose usually connect?
To the thermostat housing on the intake manifold or cylinder head
What is the typical radiator cap pressure?
12 to 6 psi
What are the main parts of a water pump?
1. Water pump impeller
2. Shaft
3. Seal
4. Bearing
5. Hub
6. Housing
Why are radiator fan blades often curled at the tips?
To increase the capacity to move air through the radiator
What is another name for a variable pitch fan?
Flex fan
What fluid in used in the fluid coupling fan clutch?
Silicone-based oil
What controls the fan action in a thermostatic fan clutch?
A temperature-sensitive bimetallic spring
What type of radiator fan is used on front-wheel drive vehicles with transverse mounted engines?
An electric fan that uses a small DC motor and a thermostatic switch to provide the cooling action
What is the purpose of the radiator shroud?
To prevent air from circulating between the back of the radiator and the front of the fan
What term is used for the water passages within the cylinder block and cylinder head?
The water jacket
What conditions can develop if an engine is allowed to operate at temperatures that are too low?
Sludge buildup and excessive fuel comsumption
What conditions can develop if an engine is allowed to operate at temperatures that are too high?
1. Burnt valves
2. Faulty lubrication
3. Possible early engine failure
What are normal thermostat ratings for automobiles?
180-195 degrees F
What is another name used for the expansion tank in a cool system?
Recovery Tank
Does an expansion tank eliminate almost all of the air bubbles from a cooling system?
Yes, and this factor allows the coolant to better absorb heat
What are the 2 basic types of temperature gauges?
1. Balancing-coil, or magnetic type
2. Bimetal-thermostat type
To what minimum temperature does a 50/50 mixture of water and ethylene glycol (antifreeze) prevent the formation of ice in a cooling system?
-34F
What are the 3 basic methods of radiator flushing?
1. Fast
2. Reverse
3. Chemical
What special equipment is required for reverse flushing of a radiator?
A flushing gun device that is connected to the radiator outlet tank by a hose
When should antifreeze be changed?
When it becomes contaminated or when it is 2 years old
What is an antifreeze hydrometer used for?
To measure the freezing point of a cooling system
What color will a combustion leak turn the fluid in a combustion leak tester (Block tester)?
Yellow
What is a temperature stick?
A pencil-like device used to test a thermostat, containing a wax material composed of chemicals that melt at specific termperatures
What are the 2 most common causes of water pump failure?
1. Rust in the cooling system
2. Lack of antifreeze
What instrument can be used to listen for worn or noisy water pump bearings?
A stethoscope
What is the first step in replacing a thermostat?
Draining the coolant and removing the upper radiator hose from the engine
When replacing a thermostat, which direction should the pellet chamber face?
Inside of the engine
What should the fan belt deflection be, when the free span is <12 inches between pulleys
1/8 to 1/4 inch
What should the fan belt deflection be, when the free span is >12 inches between pulleys?
1/4 to 1/2 inch
What conditions may be caused by a slipping fan belt?
Engine overheating and a rundown battery
What are the visual clues of a radiator leak?
The presence of scale marks or watermarks below the leak on the outside of the core
What are the principal purposes for engine lubrication?
1. Reduce friction and wear between moving parts
2. Aid in heat transfer and cool the engine parts
3. Clean the inside of the engine by contaminant removal
4. Absorb shock between the moving parts
What is oil viscosity?
Also called oil weight. The viscosity if the degree of thickness of fluidity of the oil
What does the W indicate in an SAE 10W oil?
An oil that meets SAE low-temperature requirements
What type of oil is an SAE 10W-30 oil?
A multi-weight oil, which has the characteristics of a thin, light oil at cold temperature and a thicker, heavier oil when heated
What does a CC oil service rating indicate?
The oil service rating of the oil meets all of the requirements for lightly supercharged diesel engines
What does an SF oil service rating indicate?
The oil service rating of the oil meets all of the oil warranty requirement for 1980 through 1988 automotive gasoline engines
What does an SG oil service rating indicate?
The oil service rating of the oil meets all the oil warranty requirements for 1989 through current automotive gasoline engines: it is a DETERGENT oil
What is an oil pan usually made of?
Thin sheet metal or aluminum.
What is the more common name for the oil level gauge?
Dipstick
What are the 2 basic types of oil pumps?
1. Rotary
2. Gear
What is the oil pickup?
A tube extending from the oil pump to the bottom of the oil pan; 1 end is bolted or screwed into the oil pump or engine block, and the other end holds the strainer.
What is the function of the mesh screen in an oil strainer?
To strain large particles from the oil and also to pass a sufficient quantity of oil on to the inlet side of the oil pump
What are the 2 basic types of oil filter element configurations?
1. Cartridge type
2. Spin-on
Can the filter elements be either metallic or non-metallic?
Yes
What is the most popular type of filter medium?
Cotton waste or resin-treated paper
How is the filter medium held in place?
By means of placing them between 2 perforated metal sheets
What are oil galleries?
Small passages of lubricating oil placed through the cylinder block and head
How does an oil pressure warning light receive battery power?
Through the ignition switch
At what oil pressure point does the oil pressure warning light turn on?
Whenever the oil pressure drops below ~15psi (for most vehicles)
What are the 2 main parts of a diesel system oil temperature regulator?
Core and housing
What are the primary types of oil lubricating system?
1. Splash
2. Force feed
3. Combination of the 2
4. Full force-feed
How are the cylinder walls lubricate in a combination splash and force feed system?
By splashing oil which is thrown off from the connecting-rod bearing
What type of lubricating system is employed in nearly all engines that have semifloating piston pins?
Force-feed lubricating system
What type of lubricating system is employed in nearly all engines that have FULL-floating piston pins?
Full force-feed
What are the main symptoms of low oil pressure in an engine?
1. Low gauge reading
2. Glowing indicator light
3. Irregular engine noises (rattling or bearings)
What are the main symptoms of high oil pressure in an engine?
1. High gauge reading
2. Swollen oil filter
What is the usual source of external oil leakage?
Leaking gaskets or seals
What effects do worn connecting rods or main bearing produce?
The pump cannot provide sufficient oil volume
How often should the oil and filter in a newer automobile be changed?
Every 5,000 miles
How often should the oil and filter in older automobile be changed?
Every 3,000 miles
How often should the oil be changed in most type of construction equipment?
Between 200 and 250 HOURS of operation, on average