COMPETENCY BASED LEARNING MATERIAL
Sector:
AUTOMOTIVE
Qualifications:
Automotive Servicing NC I
Unit of Competency:
Perform Diesel Engine Tune Up
Module Title:
PERFORMING DIESEL ENGINE TUNE UP
Technical Education and Skills Development Authority
TESDA Complex, East Service Road, South Superhighway, Taguig, Metro Manila
NATIONAL CERTIFICATE LEVEL 1
QUALIFICATION LEVEL
COMPETENCY-BASED LEARNING MATERIALS
No.
Basic Competencies
1. Receive and Respond to
Workplace Communication
2. Work with Others
3. Demonstrate Work Values
4. Practice Housekeeping
Procedures
No.
Common Competencies
1. Apply Appropriate
Sealant/Adhesive
2. Move and Position Vehicle
3.
4.
5.
6
Perform Housekeeping
Perform Mensuration and
Calculation
Perform Safety Practices
Read, Interpret and Apply
Specifications and Manual
Module Title
1. Receiving and Responding to
Workplace Communication
2. Working with Others
3. Demonstrating Work Values
4. Practicing Housekeeping
Procedures
1.
2.
3.
4.
5.
6.
7.
Use and Apply Lubricant/Coolant
7.
8.
Perform Shop Maintenance
8.
No.
Core Competencies
Module Title
Applying Appropriate
Sealant/Adhesive
Moving and Positioning
Vehicle
Performing Housekeeping
Performing Mensuration and
Calculation
Performing Safety Practices
Reading, Interpreting and
Applying Specifications and
Manual
Using and Applying Lubricants/
Coolants
Perform Shop Maintenance
Module Title
Code
500311101
500311102
500311103
500311104
Code
ALT723201
ALT723202
ALT311201
ALT311202
ALT311203
ALT723203
ALT723204
ALT723205
Code
1.
Perform Diesel Engine
Tune Up
1. Performing Diesel
Engine Tune Up
ALT723301
2.
Perform Gas Engine Tune Up
ALT723302
3.
4.
5.
Service Automotive Battery
Service Ignition System
Test and Repair Wiring/Lighting
System
Perform Underchassis Preventive
Maintenance
2. Performing Gas Engine Tune
Up
3. Servicing Automotive Battery
4. Servicing Ignition System
5. Testing and Repairing Wiring/
Lighting System
6. Performing Underchassis
Preventive Maintenance
6.
ALT723303
ALT723304
ALT723305
ALT723306
How to use this Competency-Based Learning Material
Welcome to the module “Performing Diesel Engine Tune Up”. This module contains
training materials and activities for you to complete.
The unit of competency "Perform Diesel Engine Tune Up" contains the knowledge,
skills and attitudes required for Automotive Servicing. It is one of the specialized modules
at National Certificate level I (NC I).
You are required to go through a series of learning activities in order to complete
each learning outcomes of the module. In each learning outcome there are Instruction
Sheets to help you better understand the required activities. Follow these activities on your
own and answer the self-check at the end of each learning outcome. You may remove a
blank answer sheet at the end of each module (or get one from your facilitator/trainer) to
write your answers for each self-check. If you have questions, don’t hesitate to ask your
facilitator for assistance.
Instruction sheets:
• Information Sheet
- This will provide you with information (concepts,
principles and other relevant information) needed in
performing certain activities.
• Operation Sheet
- This will guide you in performing single task, operation or
process in a job.
• Job Sheet
- This is designed to guide you how to do a job that will
contribute to the attainment of the learning outcome.
• Assignment Sheet - The assignment sheet is a guide used to enhance (followup) what you have learned in the information sheet,
operation sheet or job sheet.
• Worksheet
- Worksheets are the different forms that you need to fill-up
in certain activities that you performed.
Recognition of Prior Learning (RPL)
You may already have some or most of the knowledge and skills covered in this
learner's guide 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 outcome,
you don't have to do the same training again.
Talk to your trainer about having them formally recognized. If you have a qualification
or Certificate of Competence from previous training, show it to you r trainer. If the skills you
acquired are still current and relevant to the unit/s of competency 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 learner's guide 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 back of this learner's guide is a Learner 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 also provided for
your trainer to complete once you complete the module.
Program /Course
Unit of Competency
Module
Automotive Servicing NC I
Perform Diesel Engine Tune Up
Performing Diesel Engine Tune Up
INTRODUCTION:
The purpose of a diesel engine is to convert diesel into motion so that the
vehicle can move. Currently the easiest way to create motion from diesel is to burn
the fuel inside an engine. Therefore, the engine is an internal combustion engine -combustion takes place internally.
In this module you will identify diesel engine troubles and perform tune up. You
will be performing activities to develop your skill in setting and installing injection
pump to the engine; inspecting injection timing; bleeding injection system
components and conducting compression testing.
You will also review underpinning knowledge such as types of lubricants and
fluids; automotive systems; equipment safety requirements; relevant company
policies; personal safety requirements; manual handling techniques; cleaning method
and materials; principle of engine operation; servicing inspection checklist; and
positive work values (honesty, perseverance, attention to details).
After doing the learning activities in this module you will be assessed by your
instructor on tuning up diesel engine.
LEARNING OUTCOMES
Upon completion of this module you should be able to:
1.
Set and install injection pump to engine;
2.
Inspect injection timing;
3.
Bleed injection system components;
4.
Conduct compression testing;
Code No.
ALT723301
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
1
PERFORMANCE CRITERIA
All standard of performance for Performing Diesel Engine Tune Up is in
accordance with company standard operating procedure and manufacturer’s
specification Manuals using specified tools and equipment.
1.
Set and install injection pump to engine:
1.1. Setting/installation of injection pump is performed in accordance with
manufacturer’s manual specifications.
1.2. Timing marks, torque and injection pump moving parts are checked before
installation.
1.3 Mounting bolts are tightened following torque as stated in the manual of
specifications.
1.4 No error in detecting and reading injection timing.
2.
Inspect injection timing:
2.1. Injection pump timing device is used without error.
2.2. Injection pump timing result is interpreted correctly.
2.3. Advance timing operation is checked.
3.
Bleed injection system components:
3.1. Fuel level, line leakage and fuel strainer or filters are checked.
3.2. Air lock in the system is determined without error.
3.3 Bleeder screw and prime pump is determined and used properly.
3.4 Procedures on bleeding injection system are followed guided by the service
manual.
4.
Conduct compression testing:
4.1. Engine requirements in compression testing is set and prepared.
4.2. Read and interpreted specific compression test result.
4.3 Corresponding recommendation/prescription is given based on test result.
PREREQUISITES
To complete this module you must have the completed the following modules:
- Performing Mensuration and Calculation
- Reading, Interpreting and Applying Specifications and Manual
- Using and Applying Lubricants/ Coolants
- Perform Shop Maintenance
Code No.
ALT723301
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
2
History of Diesel Engine
The diesel engine is a type of internal combustion engine that was invented by Rudolf
Diesel. He received a patent for the diesel engine in 1892 and the primary goal was to
create an efficient alternative to the gasoline engine.
Both gasoline engines and diesel engines work by creating a controlled explosion in a
sealed piston chamber. The small explosion rapidly moves the piston which in turn
rotates the output shaft. In a gasoline engine, a mixture of fuel and air are injected into
the chamber and then ignited with a spark created by a spark plug. A diesel engine, on
the other hand, does not rely on a spark plug to ignite the mixture. Fuel is forced into the
chamber and the high pressure generates enough heat to ignite the fuel/air mixture.
Some diesel engines rely on a glow plug to heat the chamber to minimize the amount of
pressure required for the engine to turn. Without such an added heat source, the
pressure required to achieve ignition (especially when the engine is cold) would be
prohibitively high.
Diesel engines require diesel fuel for the combustion process to function properly. Diesel
fuel is cheaper than regular gasoline because less refining is required. In addition, diesel
engines are more efficient and therefore diesel cars get better mileage than their
gasoline counterparts.
Diesel Engines
Diesel engines are similar to sparkignition engines in construction. Both
have pistons, with piston rings,
moving up and down in cylinders.
Both burns fuel in combustion
chambers in the upper part of the
cylinders. The high pressure
produced by the burning fuel pushes
the pistons down. This rotates the
crankshaft and the rotary motion is
carried through shafts and gears to
the drive wheels.
Diesel Engine Operation
Figure 1 shows the four pistons
strokes in a four-stroke cycle diesel
engine.
1. INTAKE STROKE. The diesel engine takes in air alone. No throttle valve impedes the
airflow.
2. COMPRESSION STROKE. The upward-moving piston compresses air alone.
3. POWER STROKE. A light oil called diesel fuel is sprayed (injected) into the
compressed and hot air. The heat of compression ignites the fuel.
4. EXHAUST STROKE. The exhaust stroke is the same for both engines. The exhaust
valve opens and the burned gases flow out as the piston moves up the cylinder.
Code No.
ALT723301
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
3
Diesel Engine Characteristics
The diesel engine has the following characteristics:
1.
2.
3.
4.
5.
No throttle valve (except some engines with the pneumatic governor).
Compresses only air on the compression stroke.
Heat of compression ignites fuel as it sprays into the engine cylinders.
Has a high compression ratio of 16:1 to 22:1.
Controls engine power and speed only by the amount of fuel sprayed into the
cylinders. More fuel equals more power.
6. Have glow plugs or an electric intake-manifold heater to make starting easier.
Figure 1. The four-piston strokes in a four-stroke-cycle diesel engine.
Diesel Fuel
Diesel engines burn diesel fuel oil. It is a light oil made from crude oil by the same
refining process that produces gasoline. The oil must have the proper viscosity, volatility,
and cetane number for use as a diesel fuel.
1. VOLATILITY. This is a measure of how easily a liquid evaporates. Gasoline vaporizes
easily. It has a high volatility. Diesel fuel has low volatility. It boils at a temperature of
about 700ºF [371ºC]. There are two grades of diesel fuel for automotive diesel
engines, number 1 diesel and number 2 diesel. Number 1 diesel is more volatile. It is
used when temperatures are very low. Number 2 diesel is the recommended fuel in
most automotive diesel engines for most driving conditions. The less-volatile fuel
usually has a higher heating value. When it burns, more energy is available than from
a fuel with higher volatility.
2. VISCOSITY. This refers to a liquid’s resistance to flow. The lower the viscosity the
more easily the liquid flows. Diesel fuel must have a relatively low viscosity. It must
flow through the fuel-system lines and spray into the engine cylinders with little
resistance. Oil with high viscosity will not break into fine particles when sprayed.
Code No.
ALT723301
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
4
Large particles burn slowly resulting in poor engine performance. If viscosity is too
low, the oil will not lubricate the moving parts in the injection pump and injection
nozzles. Damage may result. Number 2 diesel has the right viscosity for most driving
conditions. Number 1 diesel has lower viscosity so it will flow and spray properly at
low temperatures. The owner’s manual gives the proper fuel or blend to use for the
conditions.
Cetane Number
The cetane number refers to the ease with
which diesel fuel ignites. A high cetane
number means the fuel is fast burning and
ignites easily at a relatively low
temperature. A low cetane number means
the fuel is slower burning and requires a
higher temperature to ignite.
Diesel fuel with a low cetane number takes
a little longer to ignite. This may cause
excessive ignition lag. During this slight
delay, the fuel collects in the cylinder.
When ignition does occur, all the fuel
ignites at once. The pressure goes up
quickly and combustion knock results. This
is similar to spark knock or detonation in a
spark-ignition engine.
High cetane fuel ignites as soon as it
enters the cylinder.
Figure 2. The higher the cetane number of the
diesel fuel, the faster the fuel burns. The higher the
octane number of gasoline, the slower it burns.
(Ford Motor Company)
There is no accumulation of fuel. The result is a smooth pressure rise so no combustion
knock occurs.
Diesel-Engine Fuel Systems
Figure 3 shows a typical automotive diesel-engine fuel system. It uses injection nozzles
or injectors similar to the fuel injectors in gasoline fuel-injection systems. The gasoline
injectors are solenoid operated. When high pressure is applied, they open and spray
fuel. The diesel fuel system must:
1. Deliver the right amount of fuel to meet the operating requirements.
2. Time the opening of the injection nozzles so the fuel enters the engine cylinders at
the proper instant. As engine speed increases, fuel injection must start earlier. This
gives the fuel enough time to burn and produce pressure on the pistons. Without the
advance, the pistons would be over TDC and moving down before the fuel fully
ignites. This wastes fuel and power.
3. Deliver the fuel to the cylinders under high pressure. Injection pressure must be high
enough to overcome the high compression pressure in the diesel engine. At the end
of the compression stroke, compression pressure may be 500 psi [3447 kPa] or
higher.
Code No.
ALT723301
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
5
Figure 3. Typical fuel system for an automotive diesel engine. (Ford Motor Company)
Cleaning Diesel Fuel
Diesel fuel must be clean. Water or dirt in
the fuel means trouble. Tiny particles can
clog the injection nozzles and cause them
to fail. Water can rust fuel-pump and
injection-nozzle parts.
1. Water in diesel Fuel. Diesel fuel oil
absorbs water freely. Many vehicles
have a water detector located in the
fuel tank. Water sinks to the bottom of
the tank. Fuel oil floats on top. When
enough water has gathered at the
bottom of the tank (1 to 2 ½ gallons
[3.8 to 9.5 L], the water completes an
electric circuit. This turns on a warning
light on the instrument panel. To
remove the water, remove the fuel-tank
cap. Connect a pump or siphon to the
tank fuel-return hose. Pump or siphon
until all water is removed and diesel
fuel starts coming out. Reconnect the
fuel-return hose and reinstall the fuel
tank cap. Vehicles without an intank
water detector usually have a fuel
conditioner.
Code No.
ALT723301
Figure 4. Diesel fuel-gauge tank unit, with water-infuel detector mounted on the bottom of the fuel
pickup tube (Buick Division of General Motors Corp.)
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
6
This is a combination fuel filter, fuel heater and water separator. The fuel flows
through and any water settles to the bottom. Drain the water by turning the nut at the
bottom of the unit. This opens the drain valve. The fuel heater helps prevent wax from
forming in the fuel during cold weather.
2. Fuel-Pickup Bypass Valve. The fuel
pickup assembly (Figure 4) includes a
bypass valve. It allows fuel to pass if
the pickup filter becomes plugged with
wax during temperatures below 20ºF
[-6ºC]. This can happen with number 2
diesel fuel. If plugging occurs, the last
four gallons [15L] of fuel in the tank will
not be picked up. Keep the fuel tank
above ¼ full to avoid running out of
fuel.
Figure 5. A diesel fuel conditioner, which is a
combination fuel heater, fuel filter, water detector
and fuel-water separator. (Ford Motor Company)
Diesel Engine Operation
Diesel Starting Procedures.
Diesel engines require a different starting procedure from gasoline engines. If the diesel
engine is cold, the intake air must be preheated before cranking the engine. A heating
coil in an electric intake-manifold heater or in a glow plug in each precombustion
chamber (Figure LO1-13, page 19) supplies the heat.
A typical starting procedure follows.
1. When the engine is cold, turn the ignition key to ON or RUN. This connects the glow
plugs to the battery so they quickly heat the precombustion chambers. It also turns on
a WAIT light on the instrument panel. After a few seconds, the precombustion
chambers are heated sufficiently. The glow plugs and WAIT lights turn off.
2. Press the accelerator pedal halfway down.
3. Turn the ignition key to start. The engine will crank and should START. If it does not
start in 15 seconds, turn the ignition key back to ON or RUN. If the WAIT light comes on
again, leave the ignition key in ON or RUN. When the light goes off again, try starting
once more.
Pumping the accelerator pedal does not help starting a diesel engine. The fuel-injection
system has no accelerator pump as in a carburetor.
Caution: Do not use starting aids such as ether, gasoline or similar material. These can delay starting and
may cause engine damage.
Code No.
ALT723301
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
7
Coolant and Fuel Heaters
For very cold weather operation in
temperatures down to 0ºF [-18ºC] or below,
coolant and fuel heaters make starting
easier. One type of coolant heater or block
heater has an electrical element that works
when plugged into a 115-volt electric outlet.
The type of lubricating oil in the engine and
the temperature determines how long to
use the heater.
The fuel heater is a metal heating element
wound around the fuel pipe.
Figure 6. Block heater, which installs in a core-plug
hole in the cylinder block. When plugged into a 115volt electric outlet, the heating element warms the
coolant to make the engine easier to start in cold
weather. (Phillips Temro, Inc.)
The heater may be part of a fuel filter or fuel conditioner. When the ignition key is turned
the heater operates if the fuel temperature is so low that wax could form. Warming
the fuel reduces the possibility that wax will plug the filters.
ON,
Vacuum Pump
The diesel-engine car or truck needs a vacuum source to operate the power brakes and
air-conditioning vacuum motors. Many automotive diesel engines have a camshaft-driven
vacuum pump that supplies this vacuum.
Diesel Engine and Fuel-Injection Service
Servicing Diesel Engines and Fuel Systems
Basic servicing procedures on diesel engines are similar to those for spark-ignition
engines. Table LO2-1, on page 36 is a diesel fuel-injection system trouble-diagnosis
chart. Following are the procedures in servicing various diesel fuel-systems.
The transfer pump or fuel-supply pump (Figures 3) is similar to the mechanical fuel pump
used in carbureted spark-ignition engines. Air in the fuel-return line of a diesel engine
can be caused by a leak in the line between the pump and the fuel tank. This is the
vacuum side of the pump and will draw in air.
Servicing Injection Lines and Fittings
Injection lines in diesel-engine fuel-injection systems are also called high-pressure fuel
lines, injection tubes and injection pipes. They carry fuel under high pressure from the
injection pump to the injection nozzles. Figure 3 shows the various shapes of injection
lines between the injection pump and the nozzles.
When the line requires replacement, always install the line specified by the vehicle
manufacturer. Variations from specified length and internal diameter may cause engine
troubles. New lines are preformed. Avoid twisting or bending them out of shape during
installation.
Caution: Relieve the line pressure and cover the connection with a shop towel before loosening any fitting.
Code No.
ALT723301
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
8
Whenever lines are disconnected, cap the lines, nozzles and pump fittings. This prevents
dirt from entering the fuel system. Cleanliness is very important when working on the
diesel fuel system. A particle so small as to be almost invisible can clog an injection
nozzle.
Fuel Filter Service
The fuel filter (Figure 3) is located in the low-pressure fuel line from the fuel tank to the
injection pump. The filter element is similar to filters used in engine lubricating systems.
The fuel must pass through the fuel element which traps any dirt particles. Replace the
filter periodically as recommended by the manufacturer.
Code No.
ALT723301
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
9
QUALIFICATION
:
Automotive Servicing NC I
UNIT OF COMPETENCY :
Perform Diesel Engine Tune Up
MODULE TITLE
Performing Diesel Engine Tune Up
:
LEARNING OUTCOME 1 :
Set and install injection pump to engine
ASSESSMENT CRITERIA:
1.1. Setting/installation of injection pump is performed in accordance with
manufacturer’s manual specifications.
1.2. Timing marks and torque and injection pump moving parts are checked before
installation.
1.3 Mounting bolts are tightened following torque as stated in the manual of
specifications.
1.4 No error in detecting and reading injection timing.
RESOURCES:
1. Auto Mechanics, 10th edition
by: Crouse and Anglin.
2. VHS/CD
3. Communication Module
Code No.
ALT723301
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
10
LEARNING EXPERIENCES
Learning Outcome # 1: Set and install injection pump to engine
Learning Activities
1. Set and install injection pump to a
diesel engine in the presence of your
instructor.
2. Check your knowledge and skill in this
learning outcome.
Code No.
ALT723301
Special Instructions
•
Read Information Sheet LO1-1
“Diesel Fuel Injection Pumps”
•
Follow the procedures in Job Sheet
LO1-1 “Set and Install Injection Pump
to Engine”.
•
Answer the Self-Check on page 30.
•
Complete the assessment tasks. Your
trainer will guide you and check your
progress from each learning outcome
component.
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
11
SET AND INSTALL INJECTION PUMP TO ENGINE
LO1 -
LEARNING OUTCOME 1:
At the end of this learning activity you should be able to set and install injection
pump to a diesel engine.
TOOLS, EQUIPMENT AND MATERIALS:
•
•
•
•
•
•
•
•
•
•
•
Injection pump (new or reconditioned)
Service manual
Flat screwdriver
Set of wrenches (socket, box and open wrenches)
Torque wrench
Barring tool
Chisel or other permanent marking tool
Mopar MP-50
Mopar brake cleaner
Mopar silicone sealer
Optical tachometer
LEARNING ACTIVITIES:
Activity # 1:
Setting and installing injection pump to an engine.
a. Read Information Sheet LO1-1, and then answer these questions.
•
•
What is the purpose of injection pump in a diesel engine?
What are the functions of injection nozzles?
b. Perform the installation of injection pump in the presence of your
instructor.
c. Answer Self-Check LO1-1without looking at the answer key.
d. Check your answers using the answer key on page 13.
Code No.
ALT723301
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
12
INFORMATION SHEET LO1-1
DIESEL FUEL INJECTION PUMPS
Diesel Fuel Injection Pumps
Automotive diesel engines use two types
of fuel injection pumps. One is an inline
cam-operated pump. It has a plunger for
each engine cylinder. The other is a rotary,
distributor-type pump. One or two plungers
supply the fuel for all injection nozzles.
Inline-Plunger Injection Pump
Figure LO1-1 shows an inline-plunger
pump on a six-cylinder diesel engine. The
pump has a barrel-and-plunger assembly
for each cylinder.
Figure LO1-1. Fuel system for a six-cylinder diesel
engine using an inline fuel injection pump. (Robert
Bosch Corporation)
An injection line or tube connects each
barrel-and-plunger assembly to an
injection nozzle. The construction of a
barrel-and-plunger assembly is shown in
Figure LO1-2. Low-pressure fuel from the
fuel supply pump flows through the inlet
port (Figure LO1-3) into the space above
the plunger. The plunger has a roller that
rides on a cam on the camshaft. This is
like the roller tappets used in some engine
valve trains. When the cam lobe comes up
under the plunger, the lobe raises the
plunger. This applies high pressure on the
fuel trapped above the plunger. The fuel is
forced through the tube to the injection
nozzle in the cylinder where the piston is
reaching TDC on the compression stroke.
The fuel sprays out and ignites from the
heat of the compression.
The amount of fuel injected is varied by
varying the effective stroke of the plunger.
This is shown in Figure LO1-3. The control
rod connects by linkage through the
governor to the accelerator pedal. As the
driver depresses the pedal, the linkage
causes the control rod to move. This turns
the plunger in its barrel. The plunger has a
groove and an inclined helix machined into
it.
Code No.
ALT723301
Figure LO1-2. Construction of an inline-plunger
injection pump. (Robert Bosch Corporation)
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
13
Figure LO1-3. Movement of the toothed control rod turns the inline-pump plungers to vary the amount of
fuel injected. (Robert Bosch Company)
Turning the plunger for more fuel rotates the helix so a wider section faces the inlet port.
This closes the port for a longer time, increasing the effective stroke of the plunger. Fuel
delivery begins when the top edge of the plunger closes off the inlet port. Fuel delivery
stops when the helix opens the inlet port.
The fuel-injection pump has a speed-advance mechanism. It advances the time of
injection as engine speed increases. This gives the fuel the necessary time to ignite,
burn and produce high pressure. Without injection advance, weak power strokes result at
higher engine speeds.
Rotary-Distributor Injection Pump
Figure LO1-4
shows an inline
six-cylinder
engine with a
rotarydistributor
injection pump.
This pump has
a rotor that
sends fuel to
the injection
nozzles in the
engine cylinder
as it rotates.
Figure LO1-4. Fuel system for a six-cylinder diesel engine using a rotary-distributor
injection pump (Chrysler Corporation)
Code No.
ALT723301
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
14
The pump is driven by a pair of bevel
gears at half crankshaft speed.
Figure LO1-5 shows the distributor pump
removed from the engine. Figure LO1-6
and LO1-7 shows how the pump works. It
has a rotor (Figure LO1-8) with a pair of
cam rollers and plungers. These rollers
roll on the inner surface of an internal
cam. They move in and out as they roll
over the cam lobes.
When they move out, they cause the
plungers to move out. This increases the
size of the internal chamber.
Then the rollers meet the cam lobes and
push the plungers in. This pressurizes the
fuel, forcing it out through an opening in
the rotor.
The opening indexes with stationary
opening in the outer shell of the pump.
There are the same numbers of these
openings as there are cylinders in the
engine. As injection pipe connects each
opening to an injection nozzle in a
cylinder. As the motor turns, its opening
indexes with the stationary openings. This
sends high-pressure fuel to the injection
nozzles in the firing order.
Figure LO1-5. Distributor-type injection pump for a
diesel engine. (Chrysler Division of General Motors
Corporation)
Figure LO1-6. Charging cycle in the distributor pump.
The two plungers move apart to cause the fuel to
enter the chamber. (Oldsmobile Division of General
Motors Corporation)
Distributor-Pump Controls
The distributor has two controls. One
controls timing and the other controls the
amount of fuel injected. The timing device
connects to the internal cam ring. This is
the cam on which the rollers roll. As
engine speed increases, the cam ring
moves ahead. This causes the two
plungers to move out and in earlier,
advancing the start of injection (Figure
LO1-9). At the same time, the internal
governor regulates the amount of fuel
delivered to the cylinders.
Code No.
ALT723301
Figure LO1-7. Discharge cycle in the distributor
pump. The plungers are moving together, forcing fuel
from the chamber, past the delivery valve and
through the discharge port. The rotor has turned so
that the port in the rotor aligns with the next discharge
port. This port is connected in which the piston is
approaching TDC on the compression stroke.
(Oldsmobile Division of General Motors Corporation)
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
15
Mechanical Governors for fuel-Injection Pumps
Moving the accelerator pedal changes the
setting of the governor. It then
automatically controls the amount of fuel
injected.
Without a governor, a diesel engine can
stall at low speeds or run so fast it will selfdestruct. Automotive diesel engines use a
mechanical governor (centrifugal),
pneumatic, or electronically-controlled
governor. These are all variable-speed
governors. They control an engine that
runs at varying speeds.
Note: Engines that run at constant speed, such as
diesel engine that drives an electric generator, use
constant-speed governors.
Figure LO1-8. Parts in the distributor-pump rotor.
(Chevrolet Division of General Motors Corporation)
A mechanical governor has flyweights that spin with the injection-pump camshaft. The
faster they spin, the further out they move. This acts on the plungers and adjusts the fuel
delivery.
Figure LO1-10 shows an engine with a pneumatic governor. It has a throttle valve in the
intake manifold to provide a vacuum signal to the governor. This valve does not control
airflow in the engine. A venture section in the intake manifold connects by a hose to a
vacuum chamber in the governor. As the driver changes accelerator-pedal position, the
throttle-valve position also changes. This change the amount of vacuum applied to the
diaphragm in the vacuum chamber. The diaphragm moves, repositioning the control rod
in the injection pump. This rotates the plungers to vary the amount of fuel delivered.
Some diesel engines are turbocharged (Figure LO1-4). In these engines, the governor is
connected by a tube to the intake manifold. This allows the governor to match fuel
delivery with the pressure (the amount of air) in the intake manifold. Air-fuel ratios in a
diesel engine range from about 100:1 at idle to about 20:1 under full load. The governor
keeps the air-fuel ratio within these limits. An air-fuel ratio richer than 20:1 produces
unacceptable smoke in the exhaust.
Figure LO1-9. Two views of the distributor-pump automatic advance system that provides automatic
advance of injection timing. Hydraulic pressure, which increases with speed moves the cam ahead.
(Oldsmobile Division of General Motors Corporation)
Code No.
ALT723301
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
16
Diesel Electronic-Control System
A diesel engine may have an electronic
control system with an electronic control
module (ECM). The ECM may only control
the emissions systems, or it may increase
the fuel-metering accuracy of the governor.
On some engines, the electronic control
system completely replaces the
mechanical governor. The ECM monitors
sensors for engine speed, vehicle speed,
throttle position, torque-converter clutch,
and other conditions. These inputs are
evaluated. Then the ECM calculates the
correct amount of fuel to be injected.
Mechanical and pneumatic governors are
relatively slow to act. This may cause the
engine to receive the wrong amount of fuel.
Then the engine may hesitate or the airfuel ratio may be too rich, causing smoke in
the exhaust gas.
Figure LO1-10. A diesel engine with a pneumatic
governor has a throttle valve in the intake manifold
to provide a vacuum signal to the governor. (Robert
Bosch Corporation)
Electronic controls act almost instantly to
changed conditions. This maintains the
proper air-fuel ratio as operating conditions
change.
Injection Nozzle
Figures LO1-11 and LO1-12 show typical
injection nozzles. A spring holds the needle
valve or nozzle valve closed until the high
injection pressure is applied through the
injection pipe. This forces the valve off its
seat so fuel sprays out into the cylinder.
The instant the pressure drops, the spring
reseats the valve and fuel injection stops.
Figure LO1-11. Construction of a diesel-engine
injection nozzle. (Chevrolet Division of General
Motors Corporation)
Code No.
ALT723301
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
17
Figure LO1-12. Disassembled diesel-engine injection nozzle. (Ford Motor Company)
Direct and Indirect Injection
Figure 1 in “History of Diesel Engine” shows a diesel engine using direct injection. The
fuel is injected directly into the combustion chamber.
Figure LO1-13 shows indirect injection. The fuel for each cylinder is injected into a
precombustion chamber. A glow plug has a small electric heating element. It heats the
air in the precombustion chamber during cold weather to assure easy starting. Instead of
glow plugs, some diesel engines have an electronic intake manifold heater to warm the
intake air.
Figure LO1-14. Construction of a glow-plug,
showing the heating coil. (General Motors
Corporation)
Figure LO1-13. Location of precombustion
chamber, glow plug and fuel injector in a diesel
engine with indirect injection. (Volkswagen of
America, Inc.)
The fuel ignites in the precombustion chamber and streams out into the main combustion
chamber. There the burning fuel mixes with the combustion-chamber air and combustion
is completed. A diesel engine always has excess air so combustion is relatively
complete.
Diesel engine for trucks and heavy equipment use direct injection. It causes harder
starting and rougher and noisier operation. Direct injection is not normally used in
passenger-car engines.
Code No.
ALT723301
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
18
SELF-CHECK LO1-1
Direction: Select the best answer.
1. Technician A says that the diesel engine compresses air alone on the compression
stroke. Technician B says the fuel is ignited by the heat of compression. Who is right?
a. A only
b. B only
c. Both A and B
d. Neither A nor B
2. All the following are true about diesel engines EXCEPT
a. no throttle valve
b. high compression ratio
c. speed and power controlled by quantity of fuel injected
d. spark plugs make starting easier
3. Technician A says cetane number is the same as octane rating. Technician B says
cetane number is the opposite of octane rating. Who is right?
a. A only
b. B only
c. Both A and B
d. Neither A nor B
4. The distributor injection pump has
a. a rotor that sends fuel to the injection nozzles
b. a barrel-and-plunger assembly for each cylinder
c. a helix cut in each plunger
d. a control rod attached to the accelerator pedal
5. All the following are true about governors EXCEPT
a. A throttle valve in the air intake indicates a pneumatic governor
b. Moving the accelerator pedal changes the setting of the governor
c. Air-fuel ratio at full load is about 20:1
d. All automotive diesel engines use a constant-speed governor
6. The purpose of the glow plug is to
a. control engine idle speed
b. provide sparks to ignite the compressed air-fuel mixture
c. warm the fuel
d. add heat to the precombustion chamber
7. Warming the fuel with a fuel heater reduces the possibility that
a. wax in the fuel will plug the filters
b. the glow plugs will overheat
c. the coolant will freeze
d. the engine will start
Code No.
ALT723301
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
19
8. All the following are true about servicing injection lines EXCEPT
a. cap all lines to prevent dirt from entering
b. wrap a shop towel around the connection to absorb leaking fuel
c. a kinked line can be straightened and reused
d. new lines are preformed
9. Technician A says a sticking injection nozzle may cause the diesel engine to miss at
all speeds. Technician B says an injection nozzle sticking open may cause a puff of
smoke each time the engine misfires. Who is right?
a. A only
b. B only
c. Both A and B
d. Neither A nor B
Code No.
ALT723301
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
20
ANSWER KEY LO1-1
1.
c
2.
d
3.
b
4.
a
5.
d
6.
d
7.
a
8.
c
9.
c
Code No.
ALT723301
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
21
JOB SHEET LO1-1:
SET AND INSTALL INJECTION PUMP TO
ENGINE
1. Remove the injection pump
a. Label the vacuum hoses and
disconnect them from the injection
pump. (See arrows)
Figure LO1-15
b. Loosen the fuel filter union bolts and
remove the one connected to the
injection pump.
Figure LO1-16
c. Remove the delivery pipes connected
to the injection pump delivery valves
and injection nozzles.
Figure LO1-17
d. Loosen the bolts on the injection
pump cover. These bolts also hold
the injection pump.
Figure LO1-18
Code No.
ALT723301
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
22
e. Hold and support the injection pump
while removing the bolts.
Figure LO1-19
f. Pull out the injection pump from the
cover.
Figure LO1-20
2. Set the injection timing
a. Remove the timing mark cover.
Figure LO1-21
b. Find the marks on the idler gear and
the injection pump gear.
Figure LO1-22
Code No.
ALT723301
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
23
c. Return the injection pump and align
the timing marks of the injection
pump gear and the idler gear.
Figure LO1-23
d. Inspect the position of the injection
pump gear timing mark. It must be
between the idler gear timing marks.
Figure LO1-24
e. Install the bolts holding the injection
pump and tighten.
Figure LO1-25
f. Return the timing mark cover.
Figure LO1-26
Code No.
ALT723301
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
24
SELF-CHECK LO1-2
Direction: Identify the following.
a. injection pipe
b. injection nozzle
c. fuel injector
d. injection pump
1.
a.
b.
c.
d.
filter element
upper body
gasket
injection nozzle
a.
b.
c.
d.
injection pump
injector
injection nozzle
injection pipe
a.
b.
c.
d.
center bolt
fuel filter
filter element
filter housing
a.
b.
c.
d.
injector
injection pump
injection nozzle
injection pipe
2.
3.
4.
5.
Code No.
ALT723301
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
25
ANSWER KEY LO1-2
1.
d
2.
a
3.
c
4.
b
5.
d
Code No.
ALT723301
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
26
ASSESSMENT TASKS:
These assessment tasks should be completed when you are confident that you can
set and install injection pump to an engine. Assessment needs to conform to the rules of
evidence. Therefore:
•
You will need to participate and complete the learning activities
•
You will demonstrate tasks to the required standard
•
You will answer oral and written questions
•
You will complete the assessment tool
OBSERVATION CHECKLIST:
Trainer’s check
Self
check
Component
Competent
Not yet
competent
Types and functions of different injection
pumps are explained.
Methods for setting and installing the injection
pump are discussed.
Engine is adjusted to TDC.
Bolts are properly tightened to proper torque.
Checking and adjustment is performed.
Tools are properly used and stored.
Work area is cleaned.
Code No.
ALT723301
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
27
QUALIFICATION
:
Automotive Servicing NC I
UNIT OF COMPETENCY :
Perform Diesel Engine Tune Up
MODULE TITLE
Performing Diesel Engine Tune Up
:
LEARNING OUTCOME 2 :
Inspect injection timing
ASSESSMENT CRITERIA:
1. Injection pump timing device is used without error.
2. Injection pump timing result is interpreted correctly.
3. Advance timing operation is checked
RESOURCES:
Code No.
ALT723301
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
28
LEARNING EXPERIENCES
Learning Outcome # 2: Inspect injection timing
Learning Activities
Special Instructions
Identify the parts, functions and
operation of a timing device.
•
Read Information Sheet LO2-1
“Timing Device”
2. Adjust the timing of a fuel injection
pump.
•
Follow the procedures in Operation
Sheet LO2-1 “Timing the Fuel
Injection Pump”
3. Check/inspect injection nozzle.
•
Follow the procedures in Operation
Sheet LO2-2 “Checking Injection
Nozzle”
4. Check your knowledge and skill in this
learning outcome.
•
Complete the assessment tasks. Your
trainer will guide you and check your
progress from each learning outcome
component.
1.
Code No.
ALT723301
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
29
LO2 - INSPECT INJECTION TIMING
LEARNING OUTCOME 2:
At the end of this learning activity you should be able to inspect injection timing of
a diesel engine.
TOOLS, EQUIPMENT AND MATERIALS:
•
•
•
Running condition engine
Vehicle service/repair manual
(A) - 10 MM Socket wrench
(B) - 13 MM Socket wrench
(C) - 17 MM Open end wrench
(D) - 12 MM Box end wrench
(E) - 27 MM Socket (1-1/16")
LEARNING ACTIVITIES:
Activity # 1:
Inspect injection timing
a. Read Information Sheets LO2-1 and LO2-2 and perform the following:
•
•
Inspect injection pump timing of a diesel engine.
Interpret results of injection pump timing.
b. Check the advance timing operation of the engine.
Code No.
ALT723301
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
30
INFORMATION SHEET LO2-1 TIMING DEVICE
Description:
A large percentage of fuel injection pumps have timing devices incorporated in them.
Varying the time when fuel injection begins will improve diesel engine performance
and fuel economy, for the same reason that varying spark timing will improve the
performance of a gasoline engine.
1. The timing
device usually
consists of an
aluminum
casting with
mounting
flanges at both
ends. A bore in
the housing
guides and
supports the
spider
assembly.
Figure LO2-1. Diesel injection pump timing device.
A timing opening, with a cover, is located in the top of the housing and is used to
observe the position of the timing pointer in relation to the timing mark on the timing
device hub during injection pump timing procedures.
2. The timing device hub, with external left-hand helical splines for engaging the internal
helical splines of the sliding gear, has a tapered bore and keyway. The hub is
secured to the camshaft extension by a woodruff key, nut, and setscrew. The hub is
usually counterbored to receive the timing device springs. The springs oppose the
flyweight forces of the weight and spider assembly.
3. The weight and spider assembly has external right-hand helical splines which mesh
with the internal helical splines of the sliding gear. The splined end is machined to
receive the end play spacer. Three flyweights are pinned to a flange adjacent to the
splines. The weight and spider thrust plate, located between the flange and the timing
device housing, carries the back thrust of the flyweights and prevents housing wear.
Code No.
ALT723301
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
31
4. The sliding gear has internal left-hand helical splines at one end and internal righthand helical splines at the other, and meshes with the external splines of both the
weight and spider assembly and the timing device hub. Correct assembly of the
spline train is ensured by a wide land on both the hub and weight and the spider
assembly. The sliding gear has a missing tooth on each set of internal splines to
receive the wide lands.
Three arms extend from the outer surface of the sliding gear to provide seats for the
three timing device springs. The force on these springs is controlled by a sliding gear
spacer.
Operation:
1. As the engine rotates the weight and spider assembly, centrifugal force opens the
flyweights from their collapsed position against the force of the three timing device
springs.
2. As the flyweights swing
out, the sliding gear is
forced toward the
timing device hub.
3. The longitudinal
movement of the sliding
gear on its helical
spline causes a slight
change in the rotational
relationship of the
injection pump to the
engine, causing
injection to begin
slightly earlier in the
power stroke.
Figure LO2-2. Action of the flyweights during engine operation.
Code No.
ALT723301
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
32
OPERATION SHEET LO2-1 TIMING THE FUEL INJECTION PUMP
Note: Unless major repair work is done on the engine, timing should not be required.
Four cylinder firing order - 1 - 3 - 4 - 2
Procedure:
1.
Remove fuel lines from injector pump fittings on injector pump (Tool C).
2.
Pull the decompression lever so that it will remain in the decompression position. No
decompression lever on Model-12
3.
Open throttle fully.
4.
Energize the electric fuel pump and turn engine over with starter to ensure that fuel
is coming out of each injector pump opening. Have clean rags around opening to
soak up fuel.
5.
Wipe off any fuel on injector pump body and the top of each injector opening.
6.
Turn crankshaft over by hand, being careful not to damage spline on end of
crankshaft. Engine rotation will be clockwise. STOP IMMEDIATELY at the first sign
of fuel movement in the injector pump fuel fitting, for whichever injector pump is
being checked. (No. 1 injector pump is the closest to the V-belt end of the engine).
7.
Remove the cover from flywheel timing mark inspection hold located inside of left
engine mount (Tool B).
8.
Check alignment of mark on flywheel with the timing pointer on the wall of the
inspection hole. The 1-Fl mark on the flywheel represents fuel injection of No. 1
cylinder. 2-Fl represents No. 2 cylinder, etc.
9.
If timing pointer and the flywheel marking 1-Fl is aligned then No. 1 cylinder is
properly timed for fuel injection and should require no adjustment. The same will be
true for No. 2, No. 3 and No. 4 cylinders if the above steps are followed.
10. In order to determine if timing is off, or if the injection pump is faulty, it is necessary to
recheck the timing for each cylinder two or three times.
11. If there are variations in repeatability in the alignment of pointer and timing mark, a
faulty fuel injector pump may be suspected.
12. If timing marks repeat to same location but are off 3/16" or more above or below the
pointer, this indicates that the engine must be retimed.
If alignment of the timing mark is not within 3/16" above or below the pointer, the
above steps must be taken to time the engine. If the timing is found to be
satisfactory, then reconnect all fuel lines and fittings and tighten.
The fuel system must be bled before the engine will operate properly.
Code No.
ALT723301
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
33
OPERATION SHEET LO2-2 CHECKING INJECTION NOZZLE
Note: Never remove an injection nozzle from the engine except for service or replacement.
The following indicate injection-nozzle trouble:
•
•
•
•
•
One or more cylinder knocking.
Loss of power.
Smoky black exhaust.
Engine overheating.
Excessive fuel consumption.
1. One way to check injection nozzles is to run the engine at fast idle.
2. Loosen the connector at each nozzle in turn, one at a time.
3. Wrap a cloth around the connection before you loosen it to keep fuel from spurting
out. If loosening the connector causes engine speed to drop, the nozzle is probably
working normally. If the engine speed remains the same, the nozzle is not working
properly. Clogged holes are preventing fuel delivery or causing an improper spray
pattern (Table LO2-1)
Some manufacturers recommend a spray test of the detached injection nozzle. This
requires a nozzle tester, which is a special hydraulic pump and pressure gauge.
4. Attach the nozzle and apply pressure. The fuel should spray in an acceptable pattern
(Figure LO2-3) when the specified pressure is reached.
5. Releasing the pressure should stop the spray abruptly without any drip from the
nozzle.
Caution: Direct the spray from the nozzle into a suitable container. Do not allow the spray to hit your skin.
The pressure is high enough to force fuel oil through the skin. You can be seriously injured because the oil
could cause an infection.
If the engine misses at all speeds and
produces a puff of exhaust smoke each
time it misfires, an injection nozzle is
probably sticking open. The nozzle can be
disassembled and cleaned. Some
manufacturers recommend replacing a
faulty nozzle.
Caution: If you disassemble a nozzle, do not
damage the tip or enlarge the holes. This can cause
leakage and other troubles.
Figure LO2-3. Injection-nozzle spray patterns. (Ford
Motor Company)
Code No.
ALT723301
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
34
Table LO2-1: DIESEL FUEL-INJECTION SYSTEM TROUBLE-DIAGNOSIS CHART
Complaint
Possible Cause
1. Engine cranks
normally but will not
start
a. incorrect or dirty fuel
b. No fuel to nozzles or injection
pump
c. Plugged fuel-return line
d. Pump timing off
e. Inoperative glow plugs,
incorrect starting procedure,
or internal engine problems
a. Fuel low in tank
b. Incorrect fuel or dirty fuel
c. Limited fuel to nozzles or
injection pump
d. Restricted fuel-return line
e. Idle incorrectly set
f. Pump timing off
g. Injection-pump trouble
h. Internal engine problem
a. Low idle incorrect
b. Injection line leaks
c. Restricted fuel-return line
d. Nozzle trouble
e. Fuel-supply-pump problem
f. Uneven fuel distribution to
nozzles
g. Incorrect or dirty fuel.
a. Injection-pump timing off
b. Nozzle trouble
2. Engine starts but
stalls on idle
3. Rough idle, no
abnormal noise or
smoke
4. Rough idle with
abnormal noise and
smoke
5. Idle okay but
misfires as throttle
opens
6. Loss of power
a.
b.
c.
a.
b.
c.
d.
Plugged fuel filter
Injection-pump timing off
Incorrect or dirty fuel
Incorrect or dirty fuel
Restricted fuel-return line
Plugged fuel-tank vent
Restricted fuel supply
e. Plugged fuel filter
f. Plugged nozzles
7. Noise—“rap” from
one or more
cylinders
8. Combustion noise
with excessive
black smoke
Code No.
ALT723301
g. Internal engine problems,
loss of compression,
compression leaks
a. Air in fuel system
b. Gasoline in fuel system
c. Air in high-pressure line
d. Nozzle sticking open or with
low operating pressure
e. Engine problems
a. Timing off
b. Injection-pump trouble
c. Nozzle sticking open
d. Internal engine problems
Performing Diesel Engine Tune Up
Check or Correction
Flush system—use correct fuel
Check for fuel to nozzles
Check return line, clean
Retime
Fill tank
Flush system—use correct fuel
Check for fuel to nozzles and to
pump
Check return line, clean
Reset idle
Retime
Install new pump
Adjust
Fix leaks
Clear
Check, repair or replace
Check, replace if necessary
Selectively replace nozzles until
condition clears up
Flush system—use correct fuel
Retime
Check cylinders in sequence to
find defective nozzle
Replace filter
Retime
Flush system—use correct fuel
Flush system—use correct fuel
Clear
Clean
Check fuel lines, fuel-supply pump,
injection pump
Replace filter
Selectively test nozzles, replace as
necessary
Check for cause and correct
Replace fuel
Bleed system
Replace defective nozzle
Reset
Replace pump
Clean or replace
Date: Developed Date: Revised
March 4, 2006
Page #
35
ASSESSMENT TASKS:
These assessment tasks should be completed when you are confident that you can
check/replace fuel filter and air cleaner. Assessment needs to conform to the rules of
evidence. Therefore:
•
You will need to participate and complete the learning activities
•
You will demonstrate tasks to the required standard
•
You will answer oral and written questions
•
You will complete the assessment tool
OBSERVATION CHECKLIST:
Trainer’s check
Self
check
Component
Competent
Not yet
competent
Injection pump timing device is used
properly.
Results of injection pump timing are reported
to instructor.
Advanced timing is checked.
Engine components are cleaned.
Tools are properly used and stored.
Work area is cleaned.
Code No.
ALT723301
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
36
QUALIFICATION
:
Automotive Servicing NC I
UNIT OF COMPETENCY :
Perform Diesel Engine Tune Up
MODULE TITLE
Performing Diesel Engine Tune Up
:
LEARNING OUTCOME 3 :
Bleed injection system components
ASSESSMENT CRITERIA:
1. Fuel level, line leakage and fuel strainer or filters are checked.
2. Air lock in the system is determined without error.
3. Bleeder screw and prime pump is determined and used properly.
4. Procedures on bleeding injection system are followed guided by the service
manual.
RESOURCES:
Code No.
ALT723301
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
37
LEARNING EXPERIENCES
Learning Outcome # 3: Bleed injection system components
Learning Activities
Special Instructions
1. Perform bleeding of diesel engine
components with the presence of your
instructor.
•
Follow the procedures in Operation
Sheet LO3-1 “Bleeding the Fuel
System”
2. Check your knowledge and skill in this
learning outcome.
•
Complete the assessment tasks. Your
trainer will guide you and check your
progress from each learning outcome
component.
Code No.
ALT723301
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
38
LO3 - BLEED INJECTION SYSTEM COMPONENTS
LEARNING OUTCOME 3:
At the end of this learning activity you should be able to bleed injection system
components of a diesel engine.
TOOLS, EQUIPMENT AND MATERIALS:
•
•
•
•
Running condition vehicle
Vehicle service manual
Basic hand tool set
Safety glasses/goggles
LEARNING ACTIVITIES:
Activity # 1:
Bleed injection system components
a. Read Job Sheet LO3-1, and then perform the activity in the presence
of your instructor.
b. Check your knowledge of this learning outcome by completing the
assessment tasks.
Code No.
ALT723301
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
39
JOB SHEET LO3-1
BLEEDING THE FUEL SYSTEM
It will be necessary to bleed the fuel system to achieve a steady air free flow of fuel if any
of the following have occurred.
1.
Running out of fuel.
2.
If fuel shut off valve is left closed and engine runs out of fuel.
3.
Replacing fuel filter.
4.
Fuel injector nozzle or injector pump repair.
5.
After repairing or replacing any fuel line.
6.
Before putting engine back into service in the spring, if fuel system has been
drained.
7.
Replacement of electric or mechanical fuel pump.
8.
Any time air is permitted to enter the fuel system.
BLEEDING PROCEDURE:
Be sure to have some means available to catch or absorb any fuel escaping during the
bleeding process so that it will not accumulate in the engine compartment or bilge.
1.
Be sure there is a sufficient supply of fuel in the fuel tank.
2.
Open the fuel shut-off valve at the tank.
3.
Start the electric fuel pump by turning the ignition key to the "ON" position on
models 18, 20, 25, 30, 50, all models after 1986.
4.
Model 15 has a mechanical fuel pump. Therefore with decompression on, turn
engine over with starter. Crank at 10 second intervals while doing steps #5 and 7.
5.
Slowly loosen the air bleed plug on the fuel filter, letting air escape until an air free
flow of fuel is evident. (1986 models see item 7).
6.
At this time, tighten the air bleed plug on the filter.
7.
Slowly loosen the air bleed plug on the injector pump, letting air escape until an air
free flow of fuel is evident. Units with a self bleed return valve, open for a short
period then start engine, as soon as engine runs smooth close valve. Model-12 has
continuous fuel bleeding.
8.
At this time, tighten the air bleed plug or knurled knob on the injector pump.
9.
The fuel system should now be properly bled and ready for operation.
Refer to starting instructions before attempting to start the engine after bleeding the fuel
system.
Code No.
ALT723301
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
40
CAUTION: Excessive cranking with seal cock valve open can cause water accumulation in the muffler and
possibly back up into the engine. Drain muffler as needed.
FUEL INJECTORS:
Fuel injectors should be removed and taken to a qualified diesel engine repair center to
be tested for leakage and spray pattern, if poor engine performance such as loss of
power, rough or uneven running, sudden notice of dark exhaust, or engine becomes hard
to start.
REMOVING INJECTORS:
1.
Clean the area around the injectors before removing.
2.
Loosen nuts holding fuel lines to injector pump and injector nozzle and remove fuel
lines.
3.
Loosen nuts on return line adapters and remove adapters.
4.
Loosen injectors and remove injectors.
REPLACING INJECTORS:
1.
Check to be sure contact surfaces and area around injectors is clean.
2.
Replace injectors in the same cylinder from which they were removed.
3.
Torque required to properly seat the injectors will be between 43 and 58 ft./lbs.
4.
Replace fuel return lines and secure nuts.
5.
Replace all fuel lines and secure all nuts.
6.
After all injectors, fuel lines and hoses have been replaced and are secured, the
fuel system will have to be bled.
The fuel injection pump has been set at the factory and should need no adjustment. Any
apparent problem with the pump should be referred to a qualified diesel mechanic or to a
Universal Diesel dealer as advised.
NOTE: NO WARRANTY COVERAGE WILL BE GRANTED IF ANY OF THE FACTORY SET AND
SEALED FUEL AND MAXIMUM RPM. ADJUSTMENTS ARE ALTERED.
Code No.
ALT723301
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
41
ASSESSMENT TASKS:
These assessment tasks should be completed when you are confident that you can
check/replace fuel filter and air cleaner. Assessment needs to conform to the rules of
evidence. Therefore:
•
You will need to participate and complete the learning activities
•
You will demonstrate tasks to the required standard
•
You will answer oral and written questions
•
You will complete the assessment tool
OBSERVATION CHECKLIST:
Trainer’s check
Self
check
Component
Competent
Not yet
competent
Fuel level, line leakage and fuel strainer or
filters are checked.
Air lock in the system is determined without
error.
Bleeder screw and prime pump is determined
and used properly.
Procedures on bleeding injection system are
followed guided by the service manual.
Engine components are cleaned.
Tools are properly used and stored.
Work area is cleaned.
Code No.
ALT723301
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
42
QUALIFICATION
:
Automotive Servicing NC I
UNIT OF COMPETENCY :
Perform Diesel Engine Tune Up
MODULE TITLE
Performing Diesel Engine Tune Up
:
LEARNING OUTCOME 4 :
Conduct compression testing
ASSESSMENT CRITERIA:
1. Engine requirements in compression testing is set and prepared.
2. Read and interpreted specific compression test result.
3. Corresponding recommendation/prescription is given based on test result.
RESOURCES:
1. Automotive Mechanics 10th edition by Crouse and Anglin.
Code No.
ALT723301
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
43
LEARNING EXPERIENCES
Learning Outcome # 4: Conduct compression testing
Learning Activities
Special Instructions
1. Perform compression testing on a
diesel engine with the presence of
your instructor.
•
Follow the procedures in Operation
Sheet LO4-1 “Conducting
Compression Testing”
2. Check your knowledge and skill in this
learning outcome.
•
Complete the assessment tasks. Your
trainer will guide you and check your
progress from each learning outcome
component.
Code No.
ALT723301
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
44
LO4 - CONDUCT COMPRESSION TESTING
LEARNING OUTCOME 4:
At the end of this learning activity you should be able to conduct compression
testing on a diesel engine.
TOOLS, EQUIPMENT AND MATERIALS:
•
•
•
•
•
Running condition vehicle
Vehicle service manual
Basic hand tool set
Compression gauge
Safety glasses
LEARNING ACTIVITIES:
Activity # 1:
Conduct compression testing
a. Read Job Sheet LO4-1, and then perform the activity in the presence
of your instructor.
b. Interpret compression testing result on an actual engine and
recommend appropriate solutions to compression problems
encountered.
Code No.
ALT723301
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
45
JOB SHEET LO4-1:
CONDUCT COMPRESSION TESTING
The cylinder compression tester measures the ability of the cylinders to hold
compression while the starting motor cranks the engine. The compression tester is a
pressure gauge that measures the amount of pressure or compression, built-up in the
cylinder during the compression stroke. How well a cylinder holds compression is an
indication of the condition of the piston, piston rings, cylinder wall, valves and head
gasket.
1. Warm up the engine to operating temperature.
2. Stop the engine.
3. Remove the injector or injection nozzles.
4. Connect a pressure gauge to the
cylinder port as shown.
Figure LO4-1
5. Set the engine speed control to stop position.
6. Turn the engine with the starter until the pressure gauge registers no further rise in
pressure.
Note: It is a good practice to count the number of compression strokes, indicated by movement
of the gauge needle, and check each cylinder with the same number of strokes. The
engine must be at full cranking speed or as specified in appropriate service manual to get
a good reading.
7. Check the pressure reading against the engine technical manual.
Note: Low pressure indicates leakage through valves, rings or gaskets. Variations in cylinder
pressures of more than 10% usually indicate a need for cylinder reconditioning.
Code No.
ALT723301
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
46
Results of Compression Test
Engine compression readings are usually considered normal if the lowest reading is
75 percent or more of the highest.
For example, if one cylinder in an engine has a compression pressure of 120 psi (828
kPa), then all cylinders should have compression readings of 90 psi (621 kPa) or
higher. Typical compression pressures vary among engines and manufacturers. In
many General Motors engines, no cylinder should have a compression pressure of
less than 100 psi (690 kPa). Toyota specifies a maximum compression pressure of
142 psi (990 kPa) in some engines. The following section describes interpreting the
results of the compression test.
The manufacturer’s specification show what the compression pressures should be. If
compression is low, there is leakage past the piston rings, valves or cylinder-head
gasket. If the readings vary, how they vary may indicate the cause of the problem.
A Compression test made as described in Figure LO7-2 is a dry compression test. In
a spark-ignition engine, a second or wet compression test will help locate the leak.
Squirt about 1 tablespoon [15 cc] of engine oil through the spark-plug hole into the
cylinder. Recheck the compression.
Caution: Never perform a wet compression test on a diesel engine. The heat of a
compression could ignite the oil and damage the compression tester. Also, since the
oil is not compressible, it could fill the combustion chamber and create a hydrostatic
lock. This prevents the crankshaft from turning and may damage the engine.
If the compression pressure increases
to a more normal value, the low
compression probably is due to
leakage past worn piston rings.
Adding oil helps seal the rings
temporarily as the cylinder holds
compression better. Other possible
causes are a worn piston or cylinder
wall, and rings that are broken or
stuck in their piston-ring grooves.
If adding oil does not increase
compression pressure, the leakage
may be past the valves. Possible
causes include:
1.
2.
3.
4.
5.
6.
7.
Compression Gauge
Reading
Fails to climb during
all compression
strokes
20 PSI (138 kPa)
below normal
More than 20 PSI (138
kPa) below normal in
two cylinders next to
each other
20 PSI (138 kPa)
above normal
Possible Engine
Condition
Valve sticking open
Faulty rings or valve
seating
Faulty head gasket
Excessive carbon
buildup in
combustion
chamber
Figure LO4-2. Compression-gauge readings and
the probable engine conditions. (Ford Motor
Company)
Broken valve springs
Incorrect valve adjustment
Sticking valves, valves not seating
Worn or burned valves
Worn or burned valve seats
Worn camshaft lobes
Dished or worn valve lifters
Code No.
ALT723301
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
47
A blown head gasket also causes a low reading during a wet compression test. The
gasket has burned away and compression pressure leaks between the cylinder block
and head. Low or no compression in two adjacent cylinders is probably due to a
blown head gasket between the two cylinders.
Whatever the cause—rings, pistons, cylinder walls, valves, gaskets—the cylinder
head must be removed to correct the trouble. The exception is an improper valve
adjustment that holds the valves slightly off their seats. Valves are adjusted with the
cylinder head in place.
Code No.
ALT723301
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
48
ASSESSMENT TASKS:
These assessment tasks should be completed when you are confident that you can
check/replace fuel filter and air cleaner. Assessment needs to conform to the rules of
evidence. Therefore:
•
You will need to participate and complete the learning activities
•
You will demonstrate tasks to the required standard
•
You will answer oral and written questions
•
You will complete the assessment tool
OBSERVATION CHECKLIST:
Trainer’s check
Self
check
Component
Competent
Not yet
competent
Compression test is performed properly.
Results of compression tests are reported to
instructor.
Engine components are cleaned.
Tools are properly used and stored.
Work area is cleaned.
Code No.
ALT723301
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
49
PERFORMANCE TEST
Learner's Name
Date
Competency: Perform Diesel Engine Tune Up
1st
3rd
Test Attempt
2nd
OVERALL EVALUATION
Directions:
CALL YOUR INSTRUCTOR, ask
your instructor to assess your
performance in the following critical
task and performance criteria
below.
You will be rated based on the
overall evaluation on the right side.
Level
Achieved
PERFORMANCE LEVELS
4 - Can perform this skill without supervision
and with initiative and adaptability to problem
situations.
3 - Can perform this skill satisfactorily without
assistance or supervision.
2 - Can perform this skill satisfactorily but
requires some assistance and/or supervision.
1 - Can perform parts of this skill satisfactorily,
but requires considerable assistance and/or
supervision.
Instructor will initial level achieved.
PERFORMANCE STANDARDS
No
N/A
Date: Developed Date: Revised
Page #
For acceptable achievement, all items should receive a "Yes" or "N/A"
response.
Yes
1.
Setting/installation of injection pump is performed in
accordance with manufacturer’s manual specifications
2. Timing marks and torque and injection pump moving parts
are checked before installation.
3. Mounting bolts are tightened following torque as stated in the
manual of specifications.
4. No error in detecting and reading injection timing.
5. Injection pump timing device is used without error.
6. Injection pump timing result is interpreted correctly.
7. Advance timing operation is checked.
8. Fuel level, line leakage and fuel strainer or filters are
checked.
9. Air lock in the system is determined without error.
10. Bleeder screw and prime pump is determined and used
properly.
11. Procedures on bleeding injection system are followed guided
by the service manual.
Code No.
ALT723301
Performing Diesel Engine Tune Up
March 4, 2006
50
Learner’s diary
DIARY NOTES
Record important dates, jobs undertaken and other workplace events that will assist you in providing
further details to an Assessor.
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Code No.
ALT723301
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
51
Record of Achievement
Module # 1: Performing Diesel Engine Tune Up
LO 1 : Set and install injection pump to engine
Performance Criteria:
1.1.
1.2.
1.3
1.4
Setting/installation of injection pump is performed in accordance with
manufacturer’s manual specifications.
Timing marks and torque and injection pump moving parts are checked before
installation.
Mounting bolts are tightened following torque as stated in the manual of
specifications.
No error in detecting and reading injection timing.
Comments:
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Learner has satisfied the above performance criteria.
Learner’s signature:......................................................................
Trainer’s signature:.......................................................................
Date:.............................................................................................
Code No.
ALT723301
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
52
Record of Achievement
Module # 1: Performing Diesel Engine Tune Up
LO 2 : Inspect injection timing
Performance Criteria:
2.1
2.2.
2.3.
Injection pump timing device is used without error.
Injection pump timing result is interpreted correctly.
Advance timing operation is checked.
Comments:
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Learner has satisfied the above performance criteria.
Learner’s signature:......................................................................
Trainer’s signature:.......................................................................
Date:.............................................................................................
Code No.
ALT723301
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
53
Record of Achievement
Module # 1: Performing Diesel Engine Tune Up
LO 3 : Bleed injection system components
Performance Criteria:
3.1.
3.2.
3.3
3.4
Fuel level, line leakage and fuel strainer or filters are checked.
Air lock in the system is determined without error.
Bleeder screw and prime pump is determined and used properly.
Procedures on bleeding injection system are followed guided by the service
manual.
Comments:
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Learner has satisfied the above performance criteria.
Learner’s signature:......................................................................
Trainer’s signature:.......................................................................
Date:.............................................................................................
Code No.
ALT723301
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
54
Record of Achievement
Module # 1: Performing Diesel Engine Tune Up
LO 4 : Conduct compression testing
Performance Criteria:
4.1. Engine requirements in compression testing is set and prepared.
4.2. Read and interpreted specific compression test result.
4.3 Corresponding recommendation/prescription is given based on test result.
Comments:
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Learner has satisfied the above performance criteria.
Learner’s signature:......................................................................
Trainer’s signature:.......................................................................
Date:.............................................................................................
Code No.
ALT723301
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
55
Terms and Definitions
Bleeding a system:
Remove air bubbles from a brake system, a fuel injection system, or a cooling
system so that they won't impede the flow of liquid through that system.
Cetane number:
A method of rating diesel oil or fuel by measuring the time lapse between fuel
injection and ignition to determine how easy it is to ignite and how fast it will
burn. The lower the cetane number, the higher the temperature required to burn
the oil.
Compression:
[1] Applying pressure to a spring, or any springy substance, thus causing it to
reduce its length in the direction of the compressing force.
[2] Applying pressure to a gas, thus causing a reduction in volume.
[3] One of the essential factors in a internal combustion engine (fuel, air, proper
proportion of mixture, compression, timing, spark). It is the squeezing of the
fuel-air mixture in the cylinder of a spark-ignition engine or the squeezing of the
air in a diesel engine. Compression makes the process of combustion more
effective and increases engine efficiency.
[4] Term used to denote increase of pressure on a fluid by using mechanical
energy.
[5] Reduction in volume and increase in pressure and temperature of a gas
caused by squeezing it into a smaller space
Compression tester:
A device which is screwed or pushed into the spark plug hole so that when the
engine is turned over, it measures the amount of compression in that cylinder.
Delivery lines:
Fuel lines used to carry fuel from the fuel injection pump to the injector nozzles
Delivery valve:
[1] The valve on the outlet side of a pump.
[2] A fuel injection pump valve that rapidly decreases injection line pressure to
achieve an abrupt fuel cutoff at the injector
Diesel engine:
An internal combustion engine that uses diesel oil for fuel. The true diesel does
not use a carburetor or an ignition system (i.e., spark plugs) but injects diesel oil
into the cylinders when the piston has compressed the air so tightly that it is hot
enough to ignite the diesel fuel without a spark. Because a cold engine cannot
ignite the diesel fuel, glow plugs are used to heat the mixture, but they do not
provide a spark. Named after Rudolf Diesel (1858-1913), the inventor.
Diesel fuel:
A light oil fuel which has a relatively low ignition temperature.
Fuel filter:
A device that removes impurities from the fuel before it gets to the carburetor. It
Code No.
ALT723301
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
56
is usually found near the carburetor in the fuel line that comes from the fuel
pump (in-line fuel filter), or inside the carburetor (integral fuel filter) or fuel pump
(integral fuel filter). This unit must be cleaned or replaced on a regular basis,
usually once a year or it will become clogged and restrict fuel to the carburetor.
Without a filter, the jets and orifices in the carburetor will become clogged.
Idler gear:
A gear that is placed between two other gears to reverse the direction of
rotation of the output gear.
Ignition:
A process which initiates the combustion of the compressed air/fuel mixture in
the combustion chamber. In a spark-ignition engine, the mixture is ignited by an
electric spark; in a diesel engine, the self-igniting mixture must be preheated by
glow plugs when a cold start is performed.
Injection fuel:
In Bosch CIS, the pressure of the fuel in the lines between the differentialpressure valves and the injectors. Also called injector pressure.
Injection pump:
A pump which receives fuel from the fuel tank (often through the fuel-feed pump
in the case of diesel engines) and delivers it under pressure to the injectors.
Injection pump governor:
Device which controls fuel deliver to limit the minimum and maximum engine
speeds, as well as intermediate throttle positions.
Injector opening pressure:
The point at which injection pump fuel pressure overcomes nozzle valve-spring
resistance, or combustion chamber pressure, so that fuel is injected into the
pre-combustion chamber.
Injector:
Refers to the pump system (used in a fuel injection system) that squirts or
injects a measured amount of gasoline into the intake manifold in the vicinity of
the intake valve. In the diesel engine fuel is injected directly into the cylinder. In
a Continuous Injection System (CIS), the injectors atomize the continuous flow
of fuel injected under pressure into the intake ports of the engine; a valve in the
injector nozzle stops the flow of fuel when fuel pressure drops below a certain
point; in a CIS, the quantity of fuel is regulated by the fuel distributor's metering
unit; in other fuel injection systems, the fuel system delivers a constant supply of
fuel at a constant pressure to the injector, and an electronic sensing and control
system produces electrical current pulses of appropriate duration to hold open
the injector solenoid valves; as fuel pressure is held constant, varying the pulse
duration increases or decreases the amount of fuel passed through the
injectors.
Injector nozzle:
The tip of the injector, either of multi-hole design for direct injection or pintle
design for indirect injection.
Code No.
ALT723301
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
57
Nozzle:
A thin hollow tube; a jet or hole at the end of a pipe.
Pneumatics:
The study of pressure and flow in gases. A pneumatic drill is operated by
compressed air; a pneumatic tire contains compressed air.
Timing:
One of the essential factors in a internal combustion engine (Fuel, Air, Proper
proportion of mixture, compression Timing, spark). When the piston is in the
compression stroke both valves must be closed. If one or more is open, the
valve timing is out. Perhaps a timing belt or timing chain has jumped a tooth. If
the spark does not arrive at the correct moment, the engine is out of time. If this
ignition timing is only slightly off, the engine may run with less efficiency.
Timing marks:
[1] Marks or notches, usually located on the vibration damper used to
synchronize the ignition system so that the plugs will fire at the precise time.
[2] One tooth on either the camshaft or crankshaft gear will be marked with an
indentation or some other mark. Another mark will be found on the other gear
between two of the teeth. The two gears must be meshed so that the marked
tooth meshes with the marked spot on the other gear.
Vacuum pump:
A diaphragm type of pump used to produce a vacuum.
A special high efficiency device used for creating high vacuums for testing or
drying purposes.
A mechanical device used to evacuate an air conditioning system to rid it of
moisture, air, and contaminants.
Viscosity:
[1] A measure of an oil's ability to pour or be thick. Every container of oil is
marked with the viscosity of the oil. Straight weight (also called "single viscosity"
or "single weight") oil has a single number like 30 weight. A lower number
means the oil is thinner and is particularly good for lower temperatures. A higher
number is better for hotter temperatures. Multigrade (also called "multiviscosity"
or "multiweight") oil has two numbers like 10W40. When the temperature is low,
a multigrade oil like 10W40 will act like a 10 weight oil; but when the
temperature increases, it will act like a 40 weight. In this way, a multigrade oil is
excellent for all-around driving.
[2] Comparative fluidity or stiffness of liquid adhesives, coatings, and sealers.
[3] Measurement of thickness of oil or its resistance to flow. Also see spraying
viscosity
Volatility:
The property of gasoline, alcohol, etc., to evaporate quickly and at relatively low
temperatures. For instance, gasoline is more volatile (has higher volatility) than
kerosene because it evaporates at a lower temperature.
Code No.
ALT723301
Performing Diesel Engine Tune Up
Date: Developed Date: Revised
March 4, 2006
Page #
58