(2)unit4l1_2sistema de enfriamiento componentes
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UNIT 4Cooling Systems
Unit Objectives:
The student will be able to:
1. Identify the components of engine cooling systems and explain
their function.
2. Explain cooling system maintenance and characteristics of diesel
engine coolant.
3. Remove, inspect, and install cooling system components on a
Caterpillar 3406B or 3406C engine.
Unit References:
Cooling System Design Fundamentals LEKQ7353
Coolant and Your Engine SEBD0970
A Close Look at Cat Extended Life Coolant LEDQ7330
3406B Service Manual SEBR0544
3406C Service Manual SEBR0550
Unit 4 Quiz Copy
Tooling:
8T0461 Serviceman's Tool Set or equivalent
9S8140 Pressurizing Group
5P0957 Battery/Coolant Tester
8T5296 Coolant Test Kit
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Lesson 1: Identify Cooling System Components
and Function
Objectives:
The student will be able to explain the operation of the engine
cooling system and identify related components.
References:
Cooling System Design Fundamentals LEKQ7353
Coolant and Your Engine SEBD0970
A Close Look at Cat Extended Life Coolant LEDQ7330
Introduction:
A diesel engine is dependent on the cooling system to achieve
maximum performance and engine life. Cooling system problems
may include small annoying leaks, fuel economy complaints,
accelerated engine wear, or sudden catastrophic engine failure. If the
flow of coolant in the engine stops for even a short amount of time,
there is a high risk of significant damage to the engine.
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Unit 4 4-1-2 Engine Fundamentals
Lesson 1
Fig. 4.1.1 Cooling System and Energy Distribution
The cooling of an engine depends on the principles of conduction,
convection, and radiation of heat energy in order to keep the engine
running at the proper operating temperature. The coolant receives theheat that is conducted to it from the metal components of the engine;
the engine block, the cylinder head, etc. The coolant is then forced
by the water pump from the engine to the radiator. At the radiator the
heat energy is transferred by convection to the air moving across the
fins of the radiator. In addition the engine also radiates a certain
amount of energy to the atmosphere directly in the form of heat that
is given off from the engine to the surrounding air.
The components of a cooling system for an engine are extremely
simplistic. The basic components of every cooling system include:
The water jacket
The water temperature regulator(s) (thermostat(s))
The radiator (or heat exchanger)
The pressure cap
The water pump
Hoses
The engine may also have some type of coolant cooled aftercooler,
oil cooler, hydraulic cooler, or transmission cooler.
Some marine or stationary systems may have a heat exchanger in
place of the radiator.
The pump is what causes the coolant to flow in the cooling system.
Inside the engine are coolant passages that the water flows in. These
passages include what is sometimes called a "water jacket." The
water jacket is the large cavity in the block and the head that
surrounds the cylinders of the engine. This cavity is normally full of
coolant and is what keeps the engine at a uniform temperature.
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Unit 4 4-1-3 Engine Fundamentals
Lesson 1
Fig. 4.1.2 Water Temperature Regulator
The water temperature regulator(s) (thermostat(s)) regulate the flow
of coolant to the radiator. When the engine is cold, the water
temperature regulator is closed and the water coming from the engine
is closed off from the radiator. The water is then recirculated through
the water pump, back into the engine. This helps the engine acheive
operating temperature more quickly. When the engine is warm, the
water temperature regulator allows the coolant to flow to the radiator
to be cooled before reentering the engine. The water temperature
regulator is not strictly fully open or fully closed. The water
temperature regulator modulates between open and closed in order to
keep a constant temperature in the engine. Proper engine temperature
is very important. An engine that runs too cold will not operate at a
high enough temperature to have efficient combustion and will leadto sludge buildup in the lubrication system of the engine. An engine
that runs too hot will overheat and may lead to serious damage of the
engine.
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Unit 4 4-1-4 Engine Fundamentals
Lesson 1
Fig. 4.1.4 Pressure Cap
Perhaps the most overlooked component of the cooling system is the
pressure cap. The pressure cap has a relief valve that will not allow
the pressure of the cooling system to exceed a predetermined level.
The pressure cap maintains a certain amount of pressure in the
cooling system. This is very important because, by increasing the
pressure of the cooling system by 1 psi, the boiling point of the
coolant is raised 3.25 degrees F. This allows coolant to run hotter
wihout boiling. A typical cooling system will have anywhere from a
7 psi to a 12 psi pressure cap, so this can have a significant effect on
the cooling of an engine.
Fig. 4.1.3 Radiator
The radiator is the component of the cooling system that rejects the
heat from the coolant to the air. A radiator has tubes that the coolant
flows through most generally from the top of the radiator to the bottom. At the bottom of the radiator there is a hose leading to the
pump to start the circulation over again. The tubes have fins attached
to them that help to reject the heat to the air moving across the
radiator.
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NOTE: Handout "Cooling System Design Fundamentals" (Form
LEKQ7353).
Explain coolant flow (page 5).
Explain cooling system components and types (pages 7 - 11).
Explain cooling system water treatment (page 12).
Review characteristics and benefits of Caterpillar Extended Life
Coolant (page 13).
Review cooling system design fundamentals (page 14).
NOTE: Handout "Coolant and Your Engine" (Form No.
SEBD0970).
Explain the distribution of heat dissipated from fuel burned in a
diesel engine and list the components that transfer heat to coolant
(page 4).
Explain cooling system components and operation (pages 4 - 5).
Review effects of altitude, system pressure and antifreeze
concentration on cooling system temperature (pages 6 - 7).
Discuss water quality (pages 8 - 9).
Explain the need for supplemental coolant additive for conventional
antifreeze and emphasize that the level of concentration should be
maintained between 3% - 6% (pages 9 - 12).
Explain that antifreeze not only provides freeze protection for the
coolant, but also raises the boiling point and helps prevent water
pump cavitation. All Caterpillar engines with Air to Air Aftercooling
(ATAAC) require at least 30% antifreeze in the coolant to prevent
water pump cavitation.
Review list on page 14 of recommendations to avoid coolant additive
over-concentration.
Review cooling system functional effects and failures that result from
using improper coolant (pages 16 - 24).
Review cooling system service and maintenance products (pages 25 -
30).
Unit 4 4-1-5 Engine Fundamentals
Lesson 1
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NOTE: Handout "A Close Look at Cat Extended Life Coolant"
Form No. LEDQ7330
Review advantages of using Extended Life Coolant emphasizing
fewer maintenance intervals and longer life compared to conventionalcoolant.
Unit 4 4-1-6 Engine Fundamentals
Lesson 1
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Lesson 2: Remove and Install Cooling System
Components
Objectives:
Using the appropriate Caterpillar 3404 Service Manual, the student
will demonstrate the ability to correctly remove, inspect, and install
cooling system components.
References:
3406B Service Manual SEBR0544
3406C Service Manual SEBR0550
Introduction:
To effectively perform diagnosis, repair, and service on a diesel
engine cooling system, it is necessary to be able to remove, inspect,
and install the related components.
Tooling:
8T0461 Serviceman’s Tool Set or Equivalent
9S8140 Pressurizing Group
5P0957 Battery/Coolant Tester 8T5296 Coolant Test Kit
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Lab Exercises
Using a lab engine or engine installed in a vehicle, show students
cooling system components and explain their function including
coolant pump, regulator, and radiator. Test radiator cap using 9S8140Pressurizing Group. Test coolant using 8T5296 Coolant Test Kit.
Using a lab tear-down engine, remove water pump and discuss failure
mode (bad seal, loose, eroded, or cracked impeller).
Remove temperature regulator (thermostat). Point out importance of
the seal around the thermostat and trace flow of the bypass circuit.
Unit 4 4-2-2 Engine Fundamentals
Lesson 2
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CATERPILLAR ENGINE FUNDAMENTALS
Unit 4 Quiz
Circle the best answer or fill in the blanks. Name _______________________
1. If cooling system pressure rises 1 PSI, the boiling point of the coolant:
A. increases by approximately 3 degrees F.
B. decreases by approximately 3 degrees F.
C. doesn't change.
2. The acceptable range of Supplemental Coolant Additive for conventional antifreeze coolant
used in Caterpillar engines is:
A. 1 - 2%.
B. 3 - 6%.
C. 7 - 9%.
D. not important.
3. The Supplemental Coolant Additive for conventional antifreeze coolant should be checked:
A. every PM Level 1
B. every PM Level 2
C. every day
4. When the cooling system thermostat is closed, coolant circulates mainly through the:
A. engine.
B. radiator.
C. engine and radiator.
D. engine and bypass.
5. A 50/50 solution of water and antifreeze will give freeze protection to:
A. -50 degrees F
B. -67 degrees FC. -34 degrees F
D. -20 degrees F
6. What percentage of heat energy from fuel burned in an engine actually produces power at
the flywheel?
A. 50%
B. 30 - 40%
C. 70 - 80%
D. 100%
Unit 4 - 1 - Engine Fundamentals
Quiz 4.1.1
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7. What thermodynamic principles are involved removing heat from an internal combustion
engine?
A. conduction
B. convectionC. radiation
D. all of the above
8. True/False It is acceptable to run water without any additives in a diesel engine cooling
system as long as the temperature of the environment stays above freezing.
A. True
B. False
9. True/False Extended Life Coolant lasts up to 3 times as long as conventional coolant and
requires additive only once.
A. True
B. False
10. A cooling system with a keel cooler is often found on earthmoving equipment.
A. True
B. False
Unit 4 - 2 - Engine Fundamentals
Quiz 4.1.1
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CATERPILLAR ENGINE FUNDAMENTALS
Unit 4 Quiz
Circle the best answer or fill in the blanks. Name _______________________
1. If cooling system pressure rises 1 PSI, the boiling point of the coolant:
A. increases by approximately 3 degrees F.
B. decreases by approximately 3 degrees F.
C. doesn't change.
2. The acceptable range of Supplemental Coolant Additive for conventional antifreeze
coolant used in Caterpillar engines is:
A. 1 - 2%.
B. 3 - 6%.
C. 7 - 9%.
D. not important.
3. The Supplemental Coolant Additive for conventional antifreeze coolant should be checked:
A. every PM Level 1
B. every PM Level 2
C. every day
4. When the cooling system thermostat is closed, coolant circulates mainly through the:
A. engine.
B. radiator.
C. engine and radiator.
D. engine and bypass.
5. A 50/50 solution of water and antifreeze will give freeze protection to:
A. -50 degrees F
B. -67 degrees F
C. -34 degrees F
D. -20 degrees F
6. What percentage of heat energy from fuel burned in an engine actually produces power at
the flywheel?
A. 50%
B. 30 - 40%
C. 70 - 80%
D. 100%
Unit 4 - 1 - Engine Fundamentals
Quiz 4.1.1
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7. What thermodynamic principles are involved removing heat from an internal combustion
engine?
A. conduction
B. convectionC. radiation
D. all of the above
8. It is acceptable to run water without any additives in an engine cooling system as long as the
temperature of the environment stays above freezing.
A. True
B. False
9. Extended Life Coolant lasts up to 3 times as long as conventional coolant and requires
additive only once.
A. True
B. False
10. A cooling system with a keel cooler is often found on earthmoving equipment.
A. True
B. False
Unit 4 - 2 - Engine Fundamentals
Quiz 4.1.1