(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



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.



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.




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.




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.



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).


Lesson 1



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.


Lesson 1



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



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.


Lesson 2



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



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


Quiz 4.1.1



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%


Quiz 4.1.1



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


Quiz 4.1.1

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