Performing Underchassis Preventive Maintenance

COMPETENCY BASED LEARNING MATERIAL

Sector:

AUTOMOTIVE

Distinctive Area of Competence and Qualifications:

Automotive Servicing NC I

Unit of Competency:

Perform Underchassis Preventive Maintenance

Module Title:

PERFORMING UNDERCHASSIS PREVENTIVE MAINTENANCE

Technical Education and Skills Development Authority

East Service Road, South Superhighway, Taguig, Metro Manila

AUTOMOTIVE

INDUSTRY SECTOR

NATIONAL CERTIFICATE LEVEL 1

QUALIFICATION LEVEL

COMPETENCY-BASED LEARNING MATERIALS

No. Basic Competencies Module Title Code
1. Receive and Respond to 1. Receiving and Responding to 500311101

Workplace Communication Workplace Communication 500311102
2. Work with Others 2. Working with Others 500311103
3. Demonstrate Work Values 3. Demonstrating Work Values 500311104

4. Practice Housekeeping 4. Practicing Housekeeping
Procedures Procedures

No. Common Competencies Module Title Code
1. Apply Appropriate 1. Applying Appropriate ALT723201
ALT723202
Sealant/Adhesive Sealant/Adhesive ALT311201
2. Move and Position Vehicle 2. Moving and Positioning ALT311202

3. Perform Housekeeping Vehicle ALT311203
4. Perform Mensuration and 3. Performing Housekeeping ALT723203

Calculation 4. Performing Mensuration and ALT723204
5. Perform Safety Practices Calculation
6 Read, Interpret and Apply ALT723205
5. Performing Safety Practices
Specifications and Manual
6. Reading, Interpreting and
7. Use and Apply Lubricant/Coolant Applying Specifications and
Manual
8. Perform Shop Maintenance
7. Using and Applying Lubricants/
Coolants

8. Perform Shop Maintenance

No. Core Competencies Module Title Code
1. Perform Diesel Engine Tune Up 1. Performing Diesel Engine ALT723301

2. Perform Gas Engine Tune Up Tune Up ALT723302
2. Performing Gas Engine Tune
3. Service Automotive Battery ALT723303
4. Service Ignition System Up ALT723304
5. Test and Repair Wiring/Lighting 3. Servicing Automotive Battery ALT723305
4. Servicing Ignition System
System 5. Testing and Repairing Wiring/ ALT723306

6. Perform Underchassis Lighting System
Preventive Maintenance
6. Performing
Underchassis
Preventive Maintenance

HOW TO USE THIS COMPETENCY BASED LEARNING MATERIAL

Welcome to the Module on “Performing Underchassis Preventive Maintenance”. This
module contains training materials and activities for you to complete.

The unit of competency “Perform Underchassis Preventive Maintenance” contains
the knowledge, skills and attitudes required for Automotive Servicing. This is one of the
common modules for National Certificate level I (NC I).

You are required to go through a series of learning activities in order to complete each
learning outcome of the module. In each learning outcome there are Information Sheets
and Resource Sheets and Reference Materials for further reading to help you better
understand the required activities. Follow these activities and answer the self-check at the
end of each learning outcome. You may tear a blank answer sheet at the end of each
module to reflect your answers for each self-check.

If you have questions, please don’t hesitate to ask your technical instructor/tool subject
instructors for assistance. Your facilitator will always be available to assist you during the
training.

Recognition of Prior Learning (RPL)

You may already have some or most of the knowledge and skills covered in this module
because you have:

• been working for some time
• already completed training in this area.

If you can demonstrate to your trainer that you are competent in a particular skill or skills,
talk to him/her about having them formally recognized so you don’t have to do the same
training again. If you have a qualification or Certificate of Competency from previous
trainings show it to your trainer. If the skills you acquired are still current and relevant to this
module, they may become part of the evidence you can present for RPL. If you are not sure
about the currency of your skills, discuss this with your trainer.

After completing this module ask your trainer to assess your competency. Result of your
assessment will be recorded in your competency profile. All the learning activities are
designed for you to complete at your own pace.

Inside this module you will find the activities for you to complete and at the back are the
relevant information sheets for each learning outcome. Each learning outcome may have
more than one learning activities.

At the end of this module is a Learner’s Diary. Use this diary to record important dates,
jobs undertaken and other workplace events that will assist you in providing further details to
your trainer or an assessor. A Record of Achievement is provided for you by your trainer to
accomplish once you complete the module.

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This module was prepared to help you achieve the required competency, in performing
underchassis preventive maintenance independently at your own pace with minimum
supervision from your facilitator.

- Talk to your trainer and agree on how you will both organize the training of this unit.
Read through the learning guide carefully. It is divided into sections which cover all
the skills and knowledge you need to successfully complete this module.

- Work through all the information and complete the activities in each section and
complete the self-check. Suggested references are included to supplement the
materials provided in this module.

- Most probably your trainer will also be your supervisor or manager. He/she is there
to support you and show you the correct way to do things. Ask for help.

- Your trainer will tell you about the important things you need to consider when you
are completing activities and it is important that you listen and take notes.

- Talk to more experienced work mates and ask for their guidance.

- Use the self-check questions at the end of each section to test your own progress.

- When you are ready, ask your trainer to watch you perform the activities outlined in
the learning guide.

- As you work through the activities, ask for written feedback of your progress from
your trainer. After completing each element, ask your trainer to mark on the report
that you are ready for assessment.

- When you have completed this module (or several modules) and feel confident that
you have had sufficient practice your trainer will arrange an appointment with you to
asses you. The result of your assessment will be recorded in your Competency
Achievement Record.

- Before you perform the manual exercises, read the information/operation sheet and
answer the self-check provided to confirm to your self and to your instructor that you
are equipped with knowledge necessary to perform the skill portion of the particular
learning outcomes.

- Upon completion of this module ask your instructor, to assess you. You will be given
a certificate of completion as proof that you met the standard requirements
(knowledge and skills) for this module. The assessment could be made in different
methods, as prescribed in the competency standards.

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QUALIFICATION : AUTOMOTIVE SERVICING NC I

UNIT OF COMPETENCY : PERFORM UNDERCHASSIS PREVENTIVE MAINTENANCE

MODULE TITLE : PERFORMING UNDERCHASSIS PREVENTIVE MAINTENANCE

INTRODUCTION:

This module contains information and practices in performing under chassis Preventive
Maintenance. It includes instructions on how to check clutch, brake fluid and lines,
inspect/change power transmission/different gear oil, inspect replace power steering fluid,
check/refill automatic transmission fluid, inspect/fluid air tank, check tire and tire pressure
and check under chassis body bolts and nuts. This module also consists of learning
outcomes which contains learning activities for both knowledge and skills, supported with
information sheets, self-check, and job/operation sheets, gathered from different sources.

LEARNING OUTCOMES:

At the end of this module you will be able to:

1. Check clutch and brake fluid and lines
2. Inspect/change power transmission/differential gear oil
3. Inspect/replace power steering fluid
4. Check/refill automotive transmission fluid
5. Inspect/bleed air tank
6. Checks tire and tire pressure
7. Check underchassis body bolts and nuts

ASSESSMENT CRITERIA:

1.1 Clutch/brake fluid level and lines are checked for leakage.
1.2 Clutch/brake lines are checked for cracks, twists, bends, looseness and restrictions.
1.3 Low level of fluids in the master cylinder refilled to the maximum level.
1.4 Defective clutch/brake system components are replaced in accordance with

manufacturer’s specification.

2.1 Transmission/differential checked for leakage.
2.2 Transmission/differential gear oil level is checked.
2.3 Transmission/differential gear oil is changed in compliance with manufacturer’s

specification.
2.4 Transmission/differential gear oil is refilled to specified level.

3.1 Technical data pertaining to power steering fluid are accessed.
3.2 Power steering fluid level is checked.
3.3 Power steering linkages are inspected for leakage.
3.4 Power steering fluid is replaced in accordance with manufacturer’s specification.

4.1 Automatic transmission is checked for leakage.
4.2 Automatic transmission fluid is checked in accordance with service manual.
4.3 Transmission fluid is refilled to specified level.

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5.1 Data pertaining to air tank obtained.
5.2 Air tank inspected for moisture and leakage.
5.3 Air tank bleed/drained of accumulated water.

6.1 Tires are inspected for solid objects struck.
6.2 Tires are inspected for wear and deformities in accordance with manufacturer’s

specifications.
6.3 Causes of abnormal tire wear are determined.
6.4 Tire pressures are checked in accordance with manufacturer’s specification.

7.1 Body bolts and nuts are checked for tightness or damage.
7.2 Cross member bolts and nuts checked for tightness.
7.3 Transmission mounting bolts and nuts are checked for tightness and damage.
7.4 Propeller shaft bolts and nuts are checked for tightness and damage.
7.5 Leaf spring shackle, center U-bolts and nuts checked for tightness and damage

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Qualification Automotive Servicing NCI

Module Title Performing Underchasis Preventive Maintenance

Learning Outcome #1 Check clutch/brake fluid and lines

Assessment Criteria : 1. Clutch / brake fluid level and line checked.
2. Clutch/brake line checked for cracks, twists, bends, loose

and restricted lines.
3. Low levels of fluid in master cylinder refilled to maximum

level.

Resources :

1. Automotive brake system (shop manual) pp. 53-74
Eichhorn, Lane
pp. 536-552
2. Automotive Mechanics, 10th edition Crouse, pp. 711-727
William H. and Anglin, Donald L. pp. 384-385

3. Chemistry, Mendoza, Estrella E. and pp. cover page
Religioso, Teresita F.

4. Mathematics for Technical and Vocational
Students, 9th edition Boyce, John G. etal.

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LEARNING EXPERIENCES

Learning Outcome#1 : Check clutch, brake fluid and lines

Learning Activity #1 Resources
Are you ready to perform this activity?

If ready, take your time and be sure to observe 5 good
housekeeping in all your activities.

1. Read: Resources for information on fluid in the Automotive Brake System (shop

clutch master and clutch operation, brake master Manual), Lane Eichhom, Drew

operation and component parts. Connchock, pp 53.

1.1 Note that a compound part of clutch/brake Mathematics for Technical and

requires knowledge of conversion of units in Vocational Students 9th edition,

liquid. John B. Boyce, et.al. cover page

2. Read: Resource for information on checking fluid
in the line.

3. Read: Resources to identify characteristics of Chemistry, Estrella Mendoza, pp

brake fluid. 384-385

4. Read: Resources for types and uses of fluid, its Automotive Brake System (Shop
chemical composition and how fluid is used in the Manual), pp 55-74
system.

5. Answer: Self-Check #1 to asses your knowledge
to check clutch, brake fluid and lines.

6. Refer to Model Answer #1 for the correct answers
of self check

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INFORMATION SHEET LO1-1

Checking Clutch, Brake Fluid and Lines

BRAKE FLUID

Brake fluid is a chemically-inert hydraulic fluid used to transmit force and motion. It also
lubricates the pistons in the master cylinder, wheel cylinders, and calipers, There are three
types of brake fluid. These are classified by the Department of Transportation (DOT) as DOT 3,
DOT 4, and DOT 5. This classification must appear on the brake fluid container.

DOT 3 is most widely used. DOT4 was developed for disc brake systems which develop higher
temperatures than drum-brake systems. DOT 5 is silicone based and can take even higher
temperatures. However, DOT 5 fluid is incompatible with DOT 3 or 4 fluid and must not be
mixed with either of them. New silicone brake fluid can be identified by ifs purple color. New
DOT 3 and 4 fluids have a clear to amber color.

DOT 3 and 4 brake fluids are hygroscopic. They will absorb moisture. Moisture in brake fluid
lowers its boiling point. Hard and prolonged braking, as when going down a hill, can overheat
the brake fluid and cause the moisture to boil. This forms vapor that compresses when the
brake pedal is depressed. Then there is little pressure increase in the hydraulic system and
braking is lost.

Brake fluid is stored in air-tight containers to protect it from moisture. Master cylinders have
flexible diaphragms or sealed caps that cover the reservoirs. They prevent air from contacting
the fluid.

When checking the brake fluid level and its
appearance, the fluid level should be within 1/4 inch of
the top of the reservoir or at the reservoir's full level
marking. The fluid should be clean. There should be no
rust or other contamination. Note the level of the fluid
in each section of the reservoir for diagnostic
purposes.

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MASTER CYLINDER

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MASTER CYLINDER

Master Cylinder
Construction:

An older integral master cylinder has a single-piece cast-iron body with a dual reservoir. Most
vehicles now use a composite master cylinder.

A separate plastic reservoir attaches to the aluminum body with rubber grommets or seals.
Some master cylinders have a built-in fluid level sensor in the reservoirs. The sensor turns on a
warning light in the instrument panel when brake fluid is low.

Integral and composite master cylinders work in the same way. Two pistons move back and
forth in a common bore. The space in front of each piston serves as a fluid chamber that is kept
filled by the reservoir above it. The primary piston is closest to the fire wall and directly operated
by the pushrod from the brake pedal. The secondary piston is ahead of the primary piston.

Two holes in the bottom of each reservoir open into cylinder bore. The front hole is the vent
port. The other hole is the replenishing port. While the brakes are not applied, fluid flows
through the vent ports to fill the high-pressure chamber ahead of each piston. When the piston
moves forward as the brakes are applied, the piston pushes the seal or cup past the vent port.
This traps the fluid which is forced through the brake lines and hoses. The resulting pressure
increase then moves the pistons in the wheel cylinders and calipers to apply the brakes at the
wheels.

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The replenishing port allows fluid from the reservoir to fill the low-pressure chamber behind the
piston. When the brakes are released, return springs in the master cylinder force the pistons to
return to their released positions faster than fluid can flow back to the master cylinder. This
tends to create a momentary vacuum. To prevent a vacuum from forming, fluid flows from the
reservoir through the replenishing ports into the low pressure chamber. The fluid passes
through small holes in the pistons, around the cups and into the high-pressure chambers.
Instead of holes, some pistons have additional piston clearance to allow fluid-flow around the
outside of the seal.

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SELF-CHECK LO1-1

Check your knowledge in fluids by completing this self-check.

1. A chemically-inert hydraulic fluid used to transmit force and motion is called
______________.

2. What are the three types of fluids?

3. Types of fluid which are developed for disc-brake system and developed for higher
temperatures are called ________________.

4. A silicon-based fluid that can take even higher temperatures is called ________________.

5. What are the types of fluids that have a clear to amber color and are hygroscopic?
_____________________ .

6. During braking operation, what causes fluid to overheat and cause the moisture?

7. In the master cylinder, the primary piston is the piston that is: (Choose the correct answer.)
a. directly operated by the pushrod
b. nearest the front-end of the car
c. hydraulically operated by the secondary piston
d. needed only on vehicles with drum brakes

8. What do you call a sensor that turns on a warning light in the instrument panel when brake
fluid is low? ______________________ .

9. Parts of master cylinder that force the piston to return to its released position faster than
fluid can flow back to the master cylinder is called ______________________..

10. What are the component parts of a master cylinder?

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ANSWER KEY LO1-1

1. Brake fluid

2. a. DOT 3
b. DOT 4
c. DOT 5

3. DOT 4

4. DOT 5

5. a. DOT 3
b. DOT 4

6. Hard and prolonged braking

7. Letter a

8. Fluid level sensor

9. Return springs

10. locking
• primary piston assembly
• secondary seal
• secondary piston
• primary seal
• spring retainer
• spring
• cylinder body
• proportioner with O' ring
• quick take-up valve
• grommet
• fluid level switch
• reservoir
• diaphragm
• reservoir cover
•

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LEARNING EXPERIENCES

Learning Outcome#1 : Check clutch, brake fluid and lines Resources
Learning Activity #2

So, you’re now ready to do the next activity

• Read resource to check clutch and brake lines for
leakage, crack, twist, bend, loose and restricted lines.

• Read resource on properties of metals.

• Check the diagnostic worksheet for clutch, brake line • Checklist – Diagnostic
troubles/problems. Be sure to interpret the service Worksheet
manual correctly.

• Complete: Self-Check #2 • Self-Check #2

• Refer to Model Answer #2 for the correct answer on • Model Answer #2
self-check.

• Call your instructor to check your work. • Checklist

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INFORMATION SHEET LO1-2

BRAKE PEDAL TEST FOR FLUID LEAKS

Hydraulic brake system leaks can be internal and external leaks. Most internal master cylinder
leaks result when the cups lose their ability to seal the piston. Brake fluid leaks past the cups
internally. Sometimes it also appears as an external leak. Internal and external rubber parts
wear with usage or can deteriorate with age or fluid contamination. Moisture or dirt in the
hydraulic system can cause corrosion or deposits to form in the bore, resulting in the wear of
the cylinder bore or its parts. Although internal leaks do not cause a loss of brake fluid, they can
result in a loss of brake performance.

When external leaks occur, the system loses brake fluid. External leaks are caused by cracks or
brakes in master cylinder reservoirs, loose system connections, damaged seals, or leaking
brake lines or hoses.

To check for a brake fluid leak, perform the following procedure:

1. Run the engine at idle with the transmission in neutral.
2. Depress the brake pedal and hold it down with a constant foot pressure. The pedal should

remain firm and the foot pad should be at least 2 inches from the floor for manual brakes
and 1 inch for power brakes.
3. Hold the pedal depressed with medium foot pressure for about 15 seconds to make sure
that the pedal does not drop under steady pressure. If the pedal drops under steady
pressure, the master cylinder may have internal leak or there may be a leak in a brake line
or hose. Visually inspect the system as outlined.

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Hydraulically-operated clutch linkage is used
when clutch location makes it difficult to run
a rod or cable to it. Hydraulic clutch linkage
is used on high-performance engines.
These have strong springs in the pressure
plate assembly and would require high
pedal effort.

Operation of the hydraulic-clutch linkage
begins when the driver depresses the clutch
pedal. This forces a pressure into the
master cylinder. Pressurized fluid then
forced from the master cylinder, through a
hydraulic servo of a slave cylinder. A servo
is a device that converts hydraulic pressure
to mechanical movement.

The pressurized fluid then pushes a piston
and pushrod of the servo. The pushrod
movement operates the clutch fork and
disengages the clutch.

Hydraulic system can be designed so a light force on the clutch pedal produces a heavy force
on the clutch fork. It is done by using a small piston in the master cylinder and a large piston in
the servo. Operation of the hydraulic clutch linkage is similar to a hydraulic brake system.

The hydraulic system for a clutch includes hydraulically-operated release bearing. No clutch is
used. The servo and release bearing are included in the assembly that fits on the transmission
front-bearing. One end of the servo seals against the front of the transmission case. The
release bearing attaches to the carrier on the servo piston at the other end.

When the clutch pedal is depressed, hydraulic fluid flows from the clutch master cylinder to the
servo. The fluid pushes the servo piston out of the cylinder. This moves the release bearing
against the fingers of the clutch plate and disengages the clutch.

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METALS
General Properties of metals

Crystalline Structure. Chemical elements are
roughly categorized into three groups.
Metals, in a solid state are characterized by
the following properties:

1. Crystalline structure
2. High thermal and electrical

conductivity
3. Ability to be deformed plastically
4. High reflectivity
All elements are made up from a various
combinations of atoms. The atoms are
bonded together by various forces.
Temperature affects the energy levels within
the bonds so that at cool temperatures the
atoms are closely packed and form a solid
material. As the temperature rises, the
energy level between the atoms increases
and the solid becomes a liquid and
eventually a gas. The arrangement of the
atoms affects the properties of a metal.
During the process of solidification, the
atoms will arrange themselves in an orderly
manner called a space lattice. The smallest
unit having the same arrangement as the
crystal is called the unit cell. The unit cell
adds atoms in an orderly fashion and grows
into a large crystal. The number of atoms in
a small crystal may number in billions. The
number of atoms in the unit cell are few
depending on the crystalline system. Seven systems of atom arrangement are known to exist
but the important metals form either a cubic or hexagonal system.
The cubic shape can be either a face-centered-cubic (F.C.C.) or body-centered-cubic (B.C.C.),

the atom arrangement of the three common systems and typical metals for that structure. Some
metals will crystallize in one form and upon cooling change to another form. This type of change
is called an allotropic change and is important to the processing of some metals. Metals with the
face-centered lattice lend themselves to a ductile, plastic, workable state. Metals with the
hexagonal lattice exhibit a general lack of plasticity and rapidly lose what they do have upon
shaping such as cold forming. Metals with the body-centered lattice have properties between
these two groups.

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A and B shows the formation of a metal crystal. From random unit cells (a) crystal growth takes
place in three dimensions and continues until it is stopped by surrounding crystals (b). Crystals in a
newly solidified metal will have random shapes and sizes as shown. The crystals found in the
commercial metal are commonly called grains. While each grain has a random external shape, it is
composed of layers of atoms arranged as previously
discussed.

Within a crystal certain planes exist which are called slip
planes. When an external force is applied to the crystal,
the atoms along the slip planes move in relation to one
another. If the force is less than the elastic limit of the
material, the atoms will return to their original position after
the force is removed. If the force exceeds the elastic limit,
plastic deformation will occur. The shape of the crystal will
be permanently altered. As plastic deformation takes
place, the slip planes are said to be used up. If the force
continues, other slip planes will be brought into action or
the metal will rupture. The illustration shows how the grain
change is taking place as a metal is deformed by being
rolled to a thinner size.

Control of grain size is important to commercial metals. A fine-grain metal is usually tougher and
stronger than one with a coarse grain. A coarse-grain metal will normally be easier to form to shape
than one with a fine grain. The size of grain will obviously depend upon the use of the material. The
grain sizes of metal are affected by the rate of cooling of molten metal. Slow cooling results in the
formation of a small number of large grains. Fast cooling causes the formation of a large number of
small grains.

Cold Working and Annealing. As a metal is formed, or cold worked, slip planes are used up in the
crystals. As the slip planes are used up, the material becomes harder and stronger. This is known
as work hardening, strain hardening, or cold working of the metal. If greater strength is desired, the
effect of work hardening is good. If more forming is to be done on the part, work hardening is not
good. The effects on work hardening can be removed by a process known as recrystallization, or
annealing. Annealing is performed by heating the material followed by slow cooling. The
recrystallization process takes place with the metal in a solid state. As the metal cools, new crystals
are formed which have a new set of slip planes. The metal is once again easily deformed or
shaped. All metals are subject to cold working and annealing in varying degrees.

Alloys. An alloy is a mixture of two or more metals. Alloys consist of a base metal with small
percentages of other materials. Alloys are used to enhance the properties of the base metal such as
corrosion resistance, tensile strength, or workability. The elements of an alloy and base metal
combine as solutions, compounds, or mixtures. Alloying elements often allow the base metal to be
hardened or made stronger by heat treatment.

Corrosion, partial or complete wearing away, dissolving, or softening of any substance by
chemical or electrochemical reaction with its environment. The term corrosion specifically
applies to the gradual action of natural agents, such as air or salt water, on metals.

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The most familiar example of corrosion is the rusting of iron, a complex chemical reaction in
which the iron combines with both oxygen and water to form hydrated iron oxide. The oxide is a
solid that retains the same general form as the metal from which it is formed but, porous and
somewhat bulkier, is relatively weak and brittle.

Three methods may be used to prevent the rusting of iron: (1) alloying the iron so that it will be
chemically resistant to corrosion; (2) coating it with a material that will react with the corroding
substances more readily than the iron does and thus, while being consumed, protect the iron;
and (3) covering it with an impermeable surface coating so that air and water cannot reach it.
The alloying method is the most satisfactory but the most expensive. A good example is
stainless steel, in which chromium or chromium and nickel are alloyed with the iron; this alloy is
not only absolutely rustproof but will even resist the action of such corrosive chemicals as hot,
concentrated nitric acid. The second method, protection with an active metal, is also
satisfactory, but expensive. The most common example of this method is galvanizing, in which
iron is covered with zinc. In the presence of corrosive solutions, an electric potential is set up
between the iron and the zinc, causing the zinc to dissolve but protecting the iron as long as
any zinc remains. The third method, protection by coating the surface with an impermeable
layer, is the least expensive and therefore the most common. It is satisfactory as long as no
crack appears in the coating. Once the coating cracks, however, rusting proceeds at least as
fast as it would have with no protection. If the protective layer is an inactive metal, such as tin or
chromium, an electric potential is set up, protecting the layer but acting on the iron and causing
the rusting to proceed at an accelerated rate. The most satisfactory coatings are baked
enamels; the least expensive are such paints as red lead.

Some metals, such as aluminum, although very active chemically, appear not to corrode under
normal atmospheric conditions. Actually, aluminum corrodes rapidly, and a thin, continuous,
transparent layer of oxide forms on the surface of the metal, protecting it from further rapid
corrosion. Lead and zinc, although less active than aluminum, are protected by similar oxide
films. Copper, a comparatively inactive metal, is slowly corroded by air and water in the
presence of such weak acids as carbonic acid, producing a green, porous, basic carbonate of
copper. Green corrosion products, called verdigris or patina, appear on such copper alloys as
brass and bronze, as well as on pure copper.

Some metals, called noble metals, are so inactive chemically that they do not suffer corrosion
from the atmosphere; among them are silver, gold, and platinum. A combination of air, water,
and hydrogen sulfide will act on silver, but the amount of hydrogen sulfide normally present in
the atmosphere is so small that the degree of corrosion is negligible except for the black
discoloration, called tarnishing, produced by the formation of silver sulfide. The corrosion of
metals is more of a problem than that of other materials. Glass is corroded by strongly alkaline
solutions and concrete by sulfate-bearing waters. The corrosion resistance of glass and
concrete can be greatly increased by changes in their composition.

Aluminum is a lightweight, silvery metal. The atomic weight of aluminum is 26.9815; the
element melts at 660° C (1220° F), boils at 2467° C (4473° F), and has a specific gravity of 0.1
lb/in3 (2.7). The tensile strength of aluminum is about 89.6 MPa. Aluminum is a strongly
electropositive metal and extremely reactive. In contact with air, aluminum rapidly becomes
covered with a tough, transparent layer of aluminum oxide that resists further corrosive action.
For this reason, materials made of aluminum do not tarnish or rust. The metal reduces many
other metallic compounds to their base metals. For example, when thermite (a mixture of
powdered iron oxide and aluminum) is heated, the aluminum rapidly removes the oxygen from
the iron; the heat of the reaction is sufficient to melt the iron. This phenomenon is used in the
thermite process for welding iron.

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The oxide of aluminum is amphoteric—showing both acidic and basic properties. The most
important compounds include the oxide, hydroxide, sulfate, and mixed sulfate compounds.
Anhydrous aluminum chloride is important in the oil and synthetic-chemical industries. Many
gemstones—ruby and sapphire, for example—consist mainly of crystalline aluminum oxide.

Brake lines are made of steel. Because they are under the floor pan, they are wrapped with wire
armor to protect them from flying debris. The ends are flared in either a double flare or an ISO
flare. The flare provides maximum protection against leakage. A short flexible brake hose or flex
hose connects the steel brake lines to the wheel cylinders or calipers.

Another type of end is the block or banjo fitting. It is used with soft metal washers on each side.
A hollow bolt allows fluid to flow from the hose into the caliper.

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Check CHECKLIST LO1-1

1. Brake line for OK R A C D T Re Specify
leakage
(Replece) (Adjust) (Clean) (Disasse (Tighten) (Repair)
2. Clutch line for mble)
leakage

3. Brake line for
cracks

4. Clutch line for
cracks

5. Brake line for
twists

6. Clutch line for
twists

7. Brake line for
bends

8. Clutch line for
bends

9. Brake line for
loose
connections

10. Clutch line for
loose
connections

11. Brake line for
restriction

12. Clutch line for
restriction

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SELF-CHECK LO1-2

1. What are the two types of leaks in the hydraulic brake system?
2. In a hydraulic system, what causes corrosion or deposits to form in the bore, resulting in

the wear of the cylinder bore or its parts?
3. What kind of clutch linkage is used in high performance engines?
4. What are the properties of metal?
5. The principal structural metal craft which weigh about 0.1 lb/in3 compared to copper is

which has 0.28 lb/in3 is called _______________.
6. What are the component parts of the brake system?
7. What are the component parts of the clutch system?

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ANSWER KEY LO1-2

1. a. internal leak
b. external leak

2. moisture or dirt

3. hydraulic clutch

4 a. crystalline structure
b. high thermal and electrical conductivity
c. ability to be deformed plastically
d. high reflectivity

5. Aluminum

6. a. vacuum brake booster
b. release button
c. parking brake lever
d. parking brake cable
e. rear drum brake
f. service brake pedal
g. brake light switch
h. front disc brake
i. master cylinder
j. dual proportioning valve
k. brake lines

7. a. over center spring
b. pedal height adjustment
c. clutch pedal
d. pad
e. pin
f. master cylinder pushrod
g. free play adjustment
h. reservoir cap
i. clutch master cylinder
j. clutch cover
k. release bearing
l. friction disc
m. servo
n. bleeder valve
o. flexible hydraulic line
p. hydraulic line
q. clutch fork

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LEARNING EXPERIENCES

Learning Outcome#1 : Check clutch, brake fluid and lines

Learning Activity #3 Resources
This is your last activity for LO #1

1. Read resource for information on how to refill fluid in Automotive Brake System Shop

master cylinder to maximum level following the Manual, Lane Eichhom, Drew

manufacturer's specification. Connchock, pp. 55-56

2. Read resource on identifying hazards associated in
refilling fuel.

3. Complete self-check #3.

4. Refer to model answer #3 for the correct answers.

5. Call your instructor to check your work.

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MASTER CYLINDER FLUID LEVELS

Check the master cylinder fluid levels. Although normal brake lining wear may cause a slight
drop in fluid level, an abnormally low or empty level in either chamber is a strong indication that
there is a leak in the system. The procedure for filling the master cylinder reservoir is shown
below.

Typical Procedure for Filling the Master Cylinder Reservoir

Caution: Be careful to avoid spraying brake fluid. To protect the face, never bend directly over
the reservoir.

On some antilock brake systems, the manufacturer recommends depressurizing the system
before adding brake fluid. When depressurized, the reservoir level may rise slightly, giving a
more accurate level reading.

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SELF-CHECK LO1-3

Check your mastery of learning outcome #1 by completing or supplying answer to the
statements below.

1. Give some safety measures in refilling brake fluid to the master cylinder.

2. Give three characteristics of brake fluid.

3. The proper procedure to refill brake fluid to the master cylinder is
________________________________________________________.

4. In the master cylinder, the brake fluid level should be _______________________.

5. What is the function of brake master cylinder?

6. The diaphragm under the master cylinder cover prevents
___________________________________________ in the hydraulic system.

7. What are the component parts of the clutch system?

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ANSWER KEY LO1-3

1. goggles, hand gloves
2. chemically inert, high and low temperature
3. disconnect socket, open the reservoir cap
4. 1/2 to 3/4 inch (12.7 to 19 mm)
5. a vacuum from forming in the hydraulic system
6. build up pressure in the brake circuits

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Qualification Automotive Servicing NCI
Module Title Performing Underchasis Preventive Maintenance

Learning Outcome #2 Inspect and change power transmission and differential gear
Assessment Criteria : oil

1. Transmission and differential checked for leakage.
2. Transmission and differential gear oil level checked.
3. Transmission and differential gear oil changed in compliance

with manufacturer.
4. Transmission and differential gear oil refilled to specified

level.

Resources :

1. Automotive Transmission-Principles (CD)

2. Automotive Transmission-Layout and (CD)
Operation

3. Power Train and Underchassis- Manual

4. The Automotive Drive Trains and Chassis pp. 47-49
Unit

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LEARNING EXPERIENCES

Learning Outcome #2: Inspect/Change transmission/differential gear oil

Learning Activity #1 Resources
In this activity you will do the following

1. Read: Resource on identifying the component parts For more information, view CDs:
of transmission and their functions. • Automotive transmission
principles
1.1 Actual identification of the component parts. • Automotive transmission
1.2 Identify its functions using the correct definition principles, layout and
operation
of terms.

2. Read: Resource on identifying the component parts The automotive drive trains and
of differential and their functions. chassis unit, pp. 47-49.

2.1 Actual identification of the component parts
2.2 Identify its functions using the correct definition

of terms.

3. Read: Resource on types of gear oil and their uses Modern Technical Physics, Arthur
and application. Bieser, pp. 292-294.

4. Self-Check #4

5. Refer to Model Answer #4

6. Call Instructor to check your work in identifying parts.

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INFORMATION SHEET LO2-1

Transmission Component Parts

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GEAR LUBRICANTS

Manual transmissions, transaxles, and transfer cases are all various types of gearboxes. They
are very similar in three ways. All have:

1 Gears that transmit power
2 Splined shafts that rotate while other parts are sliding down on them.
3 Bearings that support the shafts and transfer the load to the case or housing

In the gearbox, the moving metal parts must not touch each other. They must be continuously
separated by a thin film of lubricant to prevent excessive wear and premature failure.

As gear teeth mesh, there is a sliding or wiping action between the contact faces. This action
produces friction and heat. Without lubrication, the gears would wear quickly and fail. However,
lubrication provides a fluid film between contact faces. This prevents metal-to-metal contact.
Therefore, all gearboxes have some type of lubricant or gear oil on them. Gear oil has five jobs
to do. These are:

1 To lubricate all moving parts and prevent wear
2 To reduce friction and power loss
3 To protect against rust and corrosion
4 To keep the interior clean
5 To cool the gearbox

In addition, the oil must have adequate load-carrying capacity to prevent puncturing of the oil
film. Chemical additives are mixed with gear oil to improve its load-carrying capacity. An oil that
has an additive in it to increase the load-carrying capacity is called an extreme-pressure (EP)
lubricant. Other additives are also added to the oil to improve the viscosity (thickness), to
prevent channeling (solidify) to improve stability and oxidation resistance, to prevent foaming, to
prevent rust and corrosion, and to prevent damage to the seals.

The typical gear oil is a straight mineral oil (refined crude oil) with the required additives in it.
Today, some oils are made from synthetic oil. Regardless of type, gear oils for use in most cars
and light trucks has a classification SAE 75W, 75W-80, 80W-90, 85W-90, 90, or 140.

Gear oil is not recommended for use in all gearboxes by the manufacturers. Gears which are
lightly loaded, such as planet-pinion gears in a planetary gear set, do not require oil. Therefore,
some transfer cases are filled with SAE 10W engine oil. Other transfer cases use automatic
transmission fluid (ATF).

ATF is also used as the factory fill in some manual transmissions built by Crysler. If excessive
gear rattle is heard in idle or during acceleration in direct drive or in overdrive gear. ATF may be
drained out and the transmission filled with multipurpose gear oil, such as SAE 85W-90. Some
manual transaxles are also filled with ATF.

To prevent the lubricant from leaking out, the gearbox has an oiltight case. Seals are used
around each cover and shaft. In addition, seals are provided around the input shafts and the
output shafts. The clutch shaft on many transmissions does not have a separate seal. Instead,
an oil slinger is used to throw back any oil that reaches it. Other designs have a passage in the
clutch-shaft-bearing retainer that returns to the case any oil passing through the bearing.

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SELF-CHECK LO2-1

1 What are the five jobs that gear oil does?
2 In order to improve the gear oil’s load-carrying capacity we mix it with _________________.
3 What do we call the oil that has an additive in it to increase load-carrying capacity?
4 Enumerate the types of gear that most cars and light trucks use?
5 Identify the component parts of differential.
6 Identify the component parts of transmission.

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ANSWER KEY LO2-1

1 a. to lubricate all moving parts and prevent wear
b. to reduce friction and power loss
c. to protect against rust and corrosion
d. to keep the interior clean
e. to cool the gearbox

2. Chemical additives

3. extreme pressure lubricant

4. a. SAE 75W
b. 75W-80
c. 80W-90
d. 85W-90

5. Refer your answer to resource material provided

6. Refer your answer to resource material provided

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LEARNING EXPERIENCES

Learning Outcome #2: Inspect/Change transmission/differential gear oil

Learning Activity #2 Resources

In this activity you will perform the following: Before doing the activity, read
Repair Manual and view CDs and
• Inspect transmission/differential gear oil; VHS about inspecting and
2. Read: Resource material about viscosity of checking leakage.

substances and composition of gear oil. Answer self-check #5 and check
your answers using model answer
3. Check leakage in transmission/differential. #5
4. Refill oil to specified level.
Proceed to refilling using the
manufacturer's manual.

Call your instructor to check your
work

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INFORMATION SHEET LO2-2

Automotive Lubricants

PROPER OIL VISCOSITY

Viscosity is a measure of an oil's resistance to flow. A low-viscosity oil is thin and flows easily. A
high-viscosity oil is thicker. It flows more slowly. Engine oil should have the proper viscosity so it
flows easily to all moving parts. The oil must not be too thin. Low viscosity reduces the ability of
the oil to stay in place between moving engine parts. If the oil is too thin (low viscosity), it is
forced out from between the moving parts. Rapid wear results.

Oil that is too thick (high viscosity) flows too slowly to engine parts, especially when the engine
and oil are cold. This also causes rapid engine wear. The engine runs with insufficient oil when
first starting. Also, in cold weather, a high-viscosity oil may be so thick that it prevents normal
cranking and starting. A single-viscosity oil (defined below) gets thick when cold and thin when
hot.

When properly operated and maintained, a manual transmission/transaxle normally lasts the life
of the vehicle without a major breakdown. All units are designed so the internal parts operate in
a bath of oil circulated by the motion of the gears and shafts. Some units also use a pump to
circulate oil to critical wear areas that require more lubrication than the natural circulation
provides.

Maintaining good internal lubrication is the key to long transmission/transaxle life. If the amount
of oil falls below minimum levels, or if the oil becomes too dirty, problems result.

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LUBRICANT CHECK

The transmission/transaxle gear oil level should be checked at the intervals specified in the
service manual. Normally, these ranges from every 7,500 to 30,000 miles. For service
convenience, Many units are now designed with a dipstick and filler tube accessible from
beneath the hood.
Check the oil with the engine off and the
vehicle resting on level grade. If the engine
has been running, wait 2 to 3 minutes before
checking the gear oil level.

Some vehicles have no dipstick. Instead, the
vehicle must be placed on a lift, and the oil
level checked through the fill plug opening on
the side of the unit. Clean the area around the
plug before loosening and removing it. Insert a
finger or bent rod into the hole to check the
level. The oil may be hot.

Lubricant should be level with, or not more than
1/2 inch below the fill hole. Add the proper grade lubricant as needed using a filler pump.

Manual transmission/transaxle lubricants in use
today include single and multiple viscosity gear
oils, engine oils, and automatic transmission
fluid. Always refer to the service manual to
determine the correct lubricant and viscosity
range for the vehicle and operation conditions.

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LUBRICANT REPLACEMENT

Transmission/transaxle lubricant can be changed with the manufacturer's specified intervals.
Typical intervals are 24,000 or 30,000 miles or every two years. Vehicles used for towing
trailers, off-road operation, or continuous stop-and-go driving may require shorter change
intervals.

Drive the vehicle to warm the lubricant before
placing the vehicle on the hoist.
Clean and remove the drain plug and allow
the lubricant to drain into a clean catch pan.
Inspect the lubricant for metal particles, which
may appear as a shiny, metallic color in the
lubricant. Large amounts of metal particles
indicate severe bearing, synchronizer, gear,
or housing wear.

Once all lubricant has drained, replace the
washer or apply a recommended sealant to
the threads on the drain plug and replace it.
Tighten the drain plug with the recommended torque. Fill the transmission or transaxle with the
proper lubricant.

VISUAL INSPECTION

Visually inspect the transmission/transaxle at regular intervals. Perform the following checks.

1. Check for lubricant leaks at all gaskets and seals. The transmission rear seal at the
driveline is particularly prone to leakage.

2. Check the case body for signs of porosity that show up as leakage or seepage of lubricant.

3. Push up and down on the unit. Watch the transmission mounts to see if the rubber
separates from the metal plate. If the case moves up, but not down, the mounts require
replacement.

4. Move the clutch and shift linkages around and check for loose or missing components.
Cable linkages should have no kinks or sharp bends, and all movement should be smooth.

5. Transaxle drive axle boots should be checked for cracks, deformation, or damage.

6. The constant velocity joints on transaxle drive axles should be thoroughly inspected.

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SELF-CHECK LO2-2

1. What is transmission?
2. Identify the component parts of transmission.
3. Give the types of gear oil.
4. What are the uses of gear oil.
5. Give the procedures in inspecting transmission and differential gear oil.
6. Give the procedures in changing power transmission and differential gear oil.

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ANSWER KEY LO2-2

1. An assembly of gears that provides the different gear ratios as well as neutral and
reverse, through which engine power is transmitted to the final drive to rotate the drive
wheel.

2.

3. Oil #90
Oil #140

4. A liquid lubricant is usually made from crude oil and used for lubrication between
moving parts.

5. Correct level of oil.

6. a. position the vehicle
b. open drain plug

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Qualification Automotive Servicing NCI
Module Title Performing Underchasis Preventive Maintenance

Learning Outcome # 3 Inspect and replace power steering fluid

Assessment Criteria : 1. Technical data pertaining to power steering fluid assessed.
2. Power steering fluid level checked.
3. Power steering fluid replaced in accordance with

manufacturer's specification.
4. Power steering linkages inspected for leakage.

Resources :

1. Automotive Training Manual (step 2) Mazda pp 2-16

2. The Automotive Drive Trains and Chassis pp. 129-134
Unit Francisco, Felizardo Y.

3. Automotive Technology (training manual) pp. 12, 15

4. Modern Technology Physics, 6th edition pp. 268-275
Bieser, Arthur

5. The Auto Repair Book Doyle, John pp. 325-341

6. Nissan Diesel Chassis Repair Manual pp. 45-71

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LEARNING EXPERIENCES

Learning Outcome #3: Inspect/replace power steering fluid Resources
Learning Activity #1

With complete tools, equipment and automobile vehicle,
you are going to:

1. Read: Resource material on how to inspect or Nissan Diesel Chassis

replace power steering fluid following manufacturer's Repair Manual pp. 47-71

manual.

2. Read: Resource on chemical composition of steering Modern Technical Physics Arthur

fluid. Biesser 6th edition, pp. 270-275

3. Complete: Resource to inspect/replace the following Automotive Technology
level of power steering fluid, sizes of power steering (Training Manual) p. 12
hoses, and clips and types of steering fluid.

4. Self-check #6

5. Model Answer #6

6. Call your instructor when you have completed this
task.

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INFORMATION SHEET LO3-1

POWER STEERING SYSTEMS

Hydraulic Principles Used in Power Steering

Two basic principles are used in all hydraulic power steering systems: (1) Liquids can be
compressed very little, (2) Pressure applied to a liquid makes it act equally in all directions, so
liquids can be used to transmit a force.

Pressure can be multiplied into a force. For instance, connect two cylinders, one ten times as
large in area as the other, by a tube or pipe, as shown below. Apply 100 pounds of pressure to
the liquid in both cylinders and it will produce a force ten times greater (1,000 pounds) in the
piston with the larger area. The pressure will be the same in both cylinders, but in the larger
cylinder, as a result of greater area, it produces a force greater than the pressure.

These basic hydraulic principles are applied to provide hydraulic power steering. A pump is
used to develop pressure and a cylinder to develop force. The pressure at the pump and in the
cylinder, for all practical purposes, is the same but in the cylinder it is multiplied into a work
force. The work force is reduced when pressure is reduced. Oil is the liquid used in hydraulic
power steering systems.

Basic Power Steering Systems

The primary purpose of a hydraulic power
steering system is to provide power assistance
for the driver. All such systems consist of the
same principal components. Note: Large
cylinder has ten times more piston area than
smaller cylinder.

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Interconnecting hoses and a means of driving the pump are also needed. A V-belt (or belts) is
the usual pump drive, and all components are interconnected to form an oil circuit. Circulation of
the oil is continuous when the engine is running.

Basically, the pump supplies hydraulic fluid under pressure to the control valve, which directs
the fluid to the right or left side of the power cylinder piston, depending upon the direction of turn
being made. The power cylinder, when actuated by this applied pressure, reduces the amount
of effort required at the steering wheel. Arrangement of the principal components differs
according to installation requirements. Some of these are shown in the following illustrations.

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In the so-called linkage type, the second valve and power cylinder may be separate parts and
mounted separately in the linkage, (a) or they may be in a single unit known as an in-line unit
(b).
In the semi-integral type the control valve is assembled on the steering gear, and the power
cylinder is mounted in the linkage. In the integral type, the control valve and power cylinders are
an integral part of the steering-gear assembly.

Rack-and-pinion type

The oil pump's control valve structure and operation are basically the same as the ballnut type,
except that the steering gear and power cylinder coupling are as shown below.

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FLUID LEVEL - The fluid is checked at the pump reservoir with a dispstick attached to the
reservoir cap. However, it is not simply a matter of pulling the cap and reading the dipstick, so
follow the manufacturer's procedure.

FLUID LEAKS - Clean the suspected area, then cycle the wheel from lock to lock several
times. Fluid leakage will not only cause abnormal noises, but may result in unequal and
abnormal steering efforts. If no sign of leakage are apparent, repeat the wheel cycling process
and inspection several more times. Consult the appropriate section of the service manual for
detailed information about the action necessary to correct any leaks.

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