Service Manual

S4S Diesel Engine

194618-up

DP20N P4000
DP25N P5000
DP30N P6000
DP35N P7000

For use with DP20N, DP25N, DP30N, DP35N,

P4000, P5000, P6000, P7000 Chassis Service Manual. 99729-88100
 INTRODUCTION

This service manual describes the specifications, maintenance and service procedures
for Mitsubishi diesel engines.
To maintain the performance of the engine for many years and to ensure safe operation,
it is important to use the engine correctly and conduct regular inspection and maintenance,
and it may also be necessary to take measures which involves the disassembly, inspection,
repair and reassembly of the engine and engine parts.
Read this manual carefully and understand all of the work procedures fully before
disassembling, inspecting, repairing or reassembling the engine.
The contents of the manual are based on the engine models that are being produced at
the time of publication. Due to improvements made thereafter, the actual engine that you
work on may differ partially from the one described in this manual.

Pub. No. 99729-88100

 INTRODUCTION

How to use this manual

This service manual consists of several Groups, which are arranged so as to allow you to make reference quickly to
specifications, maintenance standards, adjustment procedures and service procedures including methods for disassembly,
inspection, repair and reassembly of the Mitsubishi Diesel Engine (standard model for land use).
A short summary describing the content of each Group is given in the General Contents page, and there is also a detailed table
of contents at the beginning of each Group.
Regarding the procedures for operation and periodical maintenance of the engine, refer to the Operation and Maintenance
Manual. For information on the engine components and ordering of service parts, refer to the Parts Catalogue. Structure and
function of the engine are described in the relevant training manuals.

Methods of presentation
(1) Index numbers allotted to parts in exploded views are not only a call-out of part names listed in the text but also an indi-
cation of the sequence of disassembly.
(2) Inspections to be conducted during disassembly process are indicated in boxes in the relevant exploded views.
(3) Maintenance standards required for inspection and repair works are indicated in the appropriate positions in the text.
They are also collectively indicated in Group 2, the General Contents group.
(4) Fasteners to be tightened in “wet” condition, or with engine oil applied, are identified by [Wet] placed after tightening
torque values. If no such indication is suffixed, the fastener should be tightened in “dry” condition, or without lubricating
with engine oil.
(5) In this manual, important safety or other cautionary instructions are emphasized with the following marks headed.

DANGER

Indicates an immediately hazardous situation which, if not avoided, will result in death or serious injury.

WARNING

Indicates a potentially hazardous situation which, if not avoided, could result in death or serious injury.

CAUTION

Indicates a potentially hazardous situation which, if not avoided, may result in minor or moderate injury.

CAUTION

Indicates a potentially hazardous situation which, if not avoided, can result in property damage.

Note:
Emphasizes important matter, or indicates information useful for operation or maintenance of the engine.

I
INTRODUCTION

Terms used in this manual

Nominal
means the rated (design) size or magnitude of a part to be measured.
Standard
means the quantitative requirement for dimension of a part, clearance between parts and performance. This is given in a form of
tolerance. Therefore, the values shown are not in agreement with the design values.
Limit
means that, if this value is reached, the part must be repaired or replaced with a new part.

Abbreviations
• BTDC: Before Top Dead Center
• ATDC: After Top Dead Center
• BBDC: Before Bottom Dead Center
• ABDC: After Bottom Dead Center
• TIR: Total Indicated Runout
• API: American Petroleum Institute
• ASTM: American Society for Testing and Materials
• JIS: Japanese Industrial Standards
• LLC: Long Life Coolant
• MIL: Military Specifications and Standards (U.S.A.)
• MSDS: Material Safety Data Sheet
• SAE: Society of Automotive Engineers (U.S.A.)

Units of measurement
Measurements are based on the International System of Units (SI), and their converted metric values are indicated in
parentheses {}. For metric conversion, the following rates are used.
• Pressure: 1 MPa = 10.197 kgf/cm²
• Torque: 1 N·m = 0.10197 kgf·m
• Force: 1 N = 0.10197 kgf
• Horsepower: 1 kW = 1.341 HP = 1.3596 PS
• Meter of mercury: 1 kPa = 0.7 cmHg
• Meter of water: 1 kPa = 10.197 cmH2O (cmAq)
• Rotational speed: 1min-1 = 1 rpm

II
 INTRODUCTION

Safety Cautions
WARNING

Fire and explosion

Keep flames away Care about fuel, oil and exhaust gas leakage
Store fuel and engine oil in a well If any fuel, oil or exhaust gas leakage is found, immedi-
ventilated designated area. ately take corrective measures to stop it.
Make sure the fuel and engine oil Such leakages, if left uncorrected, can cause fuel or
container caps are tightly closed. engine oil to reach hot engine surfaces or hot exhaust
Do not use flames, do not smoke, gas to contact flammable materials, possibly leading to
and do not work near a heater or personal injury and/or damage to equipment.
other fire hazard where fuel or oil is handled or when
Use explosion-proof lighting apparatus
cleaning solvent is being used for washing parts.
When inspecting fuel, engine oil, coolant, battery elec-
Wipe off spilled fuel, oil and LLC immediately and thor-
trolyte, etc., use a flameproof light. An ordinary light, if
oughly. Spilled fuel, oil and LLC may ignite and cause
accidentally broken, may ignite and cause an explo-
a fire.
sion.
Keep surrounding area tidy and clean
Prevent electrical wires from short-circuit-
Do not leave combustible or explosive materials, such
ing
as fuel, engine oil and LLC, near the engine. Such sub-
Avoid inspecting or servicing the electrical system with
stances can cause fire or explosion.
the ground cable connected to the battery. Otherwise,
Remove dust, dirt and other foreign materials accumu-
a fire could result from short-circuiting. Be sure to dis-
lated on the engine and surrounding parts thoroughly.
connect the battery cable from the negative (-) terminal
Such materials can cause fire or the engine to over-
before beginning with the work procedure.
heat. In particular, clean the top surface of the battery
Short-circuits, possibly resulting in fire, may be caused
thoroughly. Dust can cause a short-circuit.
by a loose terminal or damaged cable/wire. Inspect the
Always operate the engine at a position at least 1 m
terminals, cables and wires, and repair or replace the
[3.28 ft.] away from buildings and other equipment to
faulty parts before beginning with the service proce-
prevent possible fire caused by engine heat.
dure.

Keep fire extinguishers and first-aid kit

handy
Keep fire extinguishers handy, and
become familiar with their usage.
Keep a first-aid kit at the designated
place where it is easily accessible
by anyone at any time.
Establish response procedures to
follow in the event of fire or accident. Provide an emer-
gency evacuation route, contact points, and means of
communication in case of emergency.

III
INTRODUCTION

WARNING

Stay clear of all rotating and moving parts

Install protective covers on rotating parts Lockout and tagout
Make sure the protective covers for Be sure to lockout and tagout before starting inspection
engine rotating parts are properly and maintenance.
installed as intended. Repair loose Lockout and tagout are effective methods of cutting off
or damaged protective covers as machines and equipment from energy sources.
necessary. To accomplish the lockout/tagout, remove the starter
Never remove the covers guarding switch key, set the battery switch to OFF and attach a
personnel from rotating parts, when the engine is oper- “Do Not Run” or similar caution tag to the starter switch.
ating. The starter switch key must be kept by the person who
When combining the engine with the engine-driven ma- performs inspection and maintenance during the work.
chine or radiator, always provide a cover on every ex-
Keep engine stopped during servicing
posed moving part such as driving belt and coupling.
Be sure to stop the engine before proceeding to inspec-
Never remove protective covers.
tion and service procedure. Never attempt to make ad-
Ensure safety of neighboring people before justments on the engine parts while the engine is
starting engine running. Rotating parts such as belt can entangle your
Before starting the engine, ensure that there is nobody body and cause serious injuries.
in the neighborhood and that no tools are left on or near
Always restore engine turning tools after
the engine. Verbally notify people around the engine or
use
in the work area when starting the engine.
Do not forget to remove the tools which have been
When the starter device is posted with a sign that pro-
used for turning the engine during inspection or servic-
hibits startup operation, do not operate the engine.
ing, after the procedure is finished. Remember also
Stay clear of moving parts during engine that the turning gear must be returned to the operating
running condition before starting the engine.
Do not approach rotating or sliding Starting the engine with the turning tools inserted or
parts of the engine when the engine with the turning gear in engagement can lead to not
is in operation. only engine damage but also personal injuries.
Keep objects likely to be caught by
rotating parts away from such parts.
If any part of the clothing or outfit-
ting is caught by a rotating part, se-
rious bodily injuries could result.

IV
 INTRODUCTION

WARNING WARNING

Be careful of burns Be careful of exhaust fume poi-

Do not touch the engine during or immedi- soning
ately after operation Operate engine in well-ventilated area
Do not touch the engine during or If the engine is installed in an en-
immediately after operation to closed area and the exhaust gas is
avoid risk of burns. ducted outside, ensure that there is
To conduct maintenance and in- no exhaust gas leak from duct
spection work, wait until the engine joints.
has cooled sufficiently, checking Take care that the exhaust gas is
the temperature gauge. not discharged toward plants or animals.
Exhaust gas from the engine contains carbon monox-
Slowly and carefully open radiator cap
Never attempt to open the radiator cap while the engine ide and other harmful substances. Operating the en-
is running or immediately after the engine stops. Give a gine in an ill-ventilated area can produce gas
sufficient cooling time to the engine coolant before poisoning.
opening the cap. WARNING
When opening the radiator cap, slowly turn the cap to
release internal pressure. To prevent scalds with steam
Protect ears from noises
gushing out, wear thick rubber gloves or cover the cap Wear ear plugs
with a cloth. Always wear ear plugs when enter-
Close the radiator cap tightly without fail. ing the machine room (engine
The coolant is very hot and under pressure during en- room). Combustion sound and me-
gine running or just after the engine stops. If the radia- chanical noise generated by the en-
tor cap is not closed tightly, steam and hot coolant may gine can cause hearing problems.
gush out and can cause scalds.

Add coolant only after the coolant tempera-

ture dropped
Do not add coolant immediately after the engine stops.
Wait until the coolant temperature lowers sufficiently to
avoid a risk of burns.

Never remove heat shields

The exhaust system, which becomes extremely hot
while the engine is operating, is provided with various
heat shields. Do not remove these heat shields. If any
of these heat shields have been removed owing to un-
avoidable circumstances during the work, be sure to re-
store them after the work is completed.

V
INTRODUCTION

WARNING CAUTION

Be careful of falling down Be careful of handling fuel, engine

Lift engine correctly oil and LLC
To lift the engine, always use a cor- Use only specified fuel, engine oil and long-
rect wire rope capable of withstand- life coolant (LLC)
ing the engine weight. Use only the fuel, oil and LLC specified in the applica-
Attach the wire rope to the lifting ble operation manual, and handle them carefully.
hangers provided on the engine us- Use of any other fuel, oil or LLC, or improper handling
ing a correct sling. may cause various engine problems and malfunctions.
During lifting process, keep the en- Obtain the Material Safety Data Sheets (MSDS) issued
gine in a well-balanced position by taking the center of by the fuel, oil and LLC suppliers, and follow the direc-
gravity of the engine into consideration. tions in the MSDSs for proper handling.
If the wire rope contacts the engine directly, place a
cloth or other soft padding to avoid damage to the en-
Handle LLC (long life coolant) carefully
When handling LLC, always wear rubber gloves and
gine and wire rope.
protective face mask. If LLC or cooling water containing
Do not climb onto the engine LLC comes into contact with your skin or eyes, or if it is
Do not climb onto the engine, nor step on any engine swallowed, you would suffer from inflammation, irrita-
parts located on the lateral sides. tion or poisoning.
To work on parts located on the upper section of en- Should LLC be accidentally swallowed, induce vomit-
gine, use a ladder, stool, etc., that is firmly secured. ing immediately and seek medical attention. Should
Climbing on the engine may not only damage engine LLC enter your eyes, flush them immediately with plen-
parts but also cause parts to fall off and result in per- ty of water and seek medical attention. If LLC splashes
sonal injuries. onto your skin or clothing, wash it away immediately
with plenty of water.
Establish firm scaffold during work
When working on the upper part of Keep flames away from LLC. The LLC can catch
the engine and other hard-to- flames, causing a fire.
reach places, use a stable work Coolant containing LLC is a hazardous material. Do not
platform. dispose of it in unauthorized manner. Abide by the ap-
Standing on a decrepit stool or plicable law and regulations when discarding drained
parts box may result in personal coolant.
injury. Do not place any unnecessary objects on a work Proper disposal of waste oil and coolant
platform. (LLC)
Do not discharge waste engine oil or coolant into sew-
erage, river, lake or other similar places. Such a way of
disposal is strictly prohibited by laws and regulations.
Dispose of waste oil, coolant and other environmentally
hazardous waste in accordance with the applicable law
and regulations, or consult a Mitsubishi dealer.

VI
 INTRODUCTION

CAUTION CAUTION

Service battery When abnormality occurs

Handle the battery correctly Stop overheated engine after cooling run
• Never use flames or allow sparks Even if the engine is about to overheat, do not stop the
to generate near the battery. The engine immediately. Abrupt stopping of an overheated
battery releases flammable engine can cause the coolant temperature to rise, re-
hydrogen gas and oxygen gas. sulting in seized engine parts. If the engine is about to
Any flames or sparks in the vicin- overheat, run the engine at low idling speed (cooling
ity could cause an explosion. operation), and stop the engine after the coolant tem-
• Do not use the battery the fluid level of which is low- perature lowers sufficiently.
ered below the lower limit line. Sustained use of the Do not add coolant immediately after stopping the en-
battery could result in an explosion. gine. Adding coolant to a hot engine can cause the cyl-
• Do not short the battery terminals with a tool or other inder heads to crack due to sudden change in
metal object. temperature. Add coolant little by little after the engine
• When disconnecting battery cables, always remove cools down to room temperature.
the cable from the negative (-) terminal first. When
Avoid immediate restart after abnormal stop
reconnecting the cables, attach the cable to the posi-
If the engine stops abnormally, do not restart the en-
tive (+) terminal first.
gine immediately. If the engine stops with an alarm,
• Charge the battery in a well-ventilated area, with all
check and remedy the cause of the problem before re-
filling hole plugs removed.
starting. Sustained use of the engine without any rem-
• Make sure the cable clamps are securely installed on
edy could result in serious engine problems.
the battery terminals. A loose cable clamp can cause
sparks that may result in an explosion. Avoid continuous engine operation with too
• Before servicing electrical components or conducting low oil pressure
electric welding, set the battery switch to the [Open/ If an abnormal engine oil pressure drop is indicated,
OFF] position or disconnect the cable from the nega- stop the engine immediately, and inspect the lubrica-
tive (-) battery terminal to cut off the electrical cur- tion system to locate the cause. Continuous engine op-
rent. eration with low oil pressure may cause bearings and
• Electrolyte (battery fluid) contains dilute sulfuric acid. other parts to seize.
Careless handling of the battery can lead to the loss
Stop the engine immediately if the fan belt
of sight and/or skin burns. Also, keep the battery fluid
breaks
off the mouth. If the fan belt breaks, stop the engine immediately.
• Wear protective goggles and rubber gloves when Continuous engine operation with the broken fan belt
working with the battery (when adding water, charg- could cause the engine to overheat and thereby the
ing, etc.). coolant to boil into steam, which may gush out from the
• If electrolyte is spilled onto the skin or clothing, reserve tank or radiator, and cause personal injuries.
immediately wash it away with lots of water. Use
soap to thoroughly clean.
• The battery fluid can cause blindness if splashing
into eyes. If it gets into eyes, immediately flush it
away with plenty of clean fresh water, and seek
immediate medical attention.
• If the battery fluid is accidentally swallowed, gargle
with plenty of water, then drink lots of water, and
seek immediate medical attention.

VII
INTRODUCTION

CAUTION

Other cautions
Modification of engine prohibited Warming-up operation
Unauthorized modification of the engine will void the After starting the engine, run the engine at low idling
manufacturer’s warranty. speeds for 5 to 10 minutes for warming-up. Start the
Modification of the engine may not only cause engine work after this operation is completed.
damage but also produce personal injuries. Warm-up operation circulates the lubricant through the
engine. Therefore, individual engine parts are well lu-
Never break the seals
bricated before they are subjected to heavy loads. This
To ensure proper engine operation, the fuel control link
is very important for longer service life, high-perfor-
is provided with seals that protect the fuel injection vol-
mance and economical operation.
ume and rotation speed settings against tampering. If
Do not conduct warm-up operation for a longer time
these seals are broken and the settings are changed,
than necessary. Prolonged warm-up operation causes
proper operation of the engine will no longer be guar-
carbon build-up in the cylinders that leads to incom-
anteed, and the following problems will be expected to
plete combustion.
occur.
• Rapid wear of moving and rotating parts Avoid engine operations in a overload con-
• Engine troubles such as damage and seizure of dition
engine parts If the engine is considered to be in an overloaded con-
• Increased consumption of fuel and lubricating oil dition which is identified by too much black smoke, etc.,
• Deterioration of engine performance due to poorly immediately reduce the load on the engine so that the
balanced fuel injection volume and governor opera- correct output and load conditions may be achieved.
tion Overloading the engine causes not only high fuel con-
sumption but also excessive carbon deposits inside the
Break-in operation
engine. Excessive carbon deposits can cause various
A new engine needs to be broken in for the first 50
engine problems and shorten the service life of the en-
hours of operation. During this period, do not subject
gine remarkably.
the engine to heavy loads.
Operating a new engine under high loads or severe Cooling operation before stopping engine
conditions during the break-in period can shorten the Always conduct the cooling operation (low speed
service life of the engine. idling) for 5 to 6 minutes before stopping the engine.
Abruptly stopping the engine immediately after high-
load operation can cause partial overheating and short-
en the service life of the engine.
During cooling operation, check the engine for abnor-
malities.

Protection of engine against water entry

Do not allow rainwater, etc. to enter the engine through
the air inlet or exhaust openings.
Do not wash the engine while it is operating. Cleaning
fluid (water) can be sucked into the engine.
Starting the engine with water inside the combustion
chambers can cause the water hammer action which
may result in internal engine damage and serious acci-
dents.

VIII
 INTRODUCTION

Maintenance of air cleaner or pre-cleaner Avoidance of prolonged time of starter oper-

The major cause of abnormal wear on engine parts is ation
dust entering with intake air. Worn parts produce many Do not operate the starter for more than 10 seconds at
problems such as an increase of oil consumption, de- a time even if the engine does not start. Wait for at least
crease of output, and starting difficulties. For effective 30 seconds before next engine cranking.
removal of dust from intake air, conduct maintenance Continuous operation of the starter will drain the battery
of the air cleaner according to the following instruc- power and cause the starter to seize.
tions.
Do not turn off battery switch during opera-
• Do not conduct maintenance of the air cleaner/pre-
tion
cleaner while the engine is operating. Engine opera-
If the battery switch is turned OFF when the engine is
tion without the air cleaner/precleaner in place allows
running, not only various meters will stop working but
foreign matters to enter the turbocharger, causing it
the alternator may have its diodes and transistors dete-
to be seriously damaged.
riorate.
• Remove the air cleaner/pre-cleaner slowly to prevent
dust accumulated on the element from falling off. Cautionary instructions for transporting en-
After removing the air cleaner or pre-cleaner, imme- gine
diately cover the opening (inlet port in case of air When transporting the engine on a truck, consider the
cleaner; port in body in case of pre-cleaner) with engine weight, width and height to ensure safety. Abide
plastic sheet or similar means to prevent dust from by traffic road laws, vehicle road acts, vehicle restric-
entering the engine. tion ordinances and other pertinent laws.
• Air cleaners equipped with a dust indicator will issue
Avoid continuous engine operation in a low
an alarm if the element gets clogged. Service the
load condition
cleaner as soon as possible if an alarm is issued. Do not operate the engine continuously for more than
Observe safety rules at work site 10 minutes at a load of less than 30%. Engine opera-
Observe the safety rules established at your workplace tion in a low load condition increases the emission of
when operating and maintaining the engine. unburned fuel. Therefore, a prolonged time of engine
Do not operate the engine if you are feeling ill. operation in a low load condition increases the quantity
Operation of the engine with reduced awareness may of unburned fuel adhering to engine parts, provoking
cause improper operation that could result in accidents. the possibility of engine malfunctioning and shortening
In such a case, inform your supervisor of your condi- the service life of the engine.
tion.
Ventilation of engine room
When working in a team of two or more people, use Always keep the engine room well ventilated. Insuffi-
specified hand signals to communicate among work- cient amount of intake air causes the operating temper-
ers. ature to rise, resulting in poor output and lowered
Work clothing and protective gear performance.
Wear a hard hat, face shield, safety shoes, dust mask, It is highly recommended to calculate the required
gloves and other protective gear as needed. amount of air supply to the engine and install an ade-
When handling compressed air, wear safety goggles, quate ventilation system before installing the engine.
hard hat, gloves and other necessary protective gear.
Avoid contact with high-pressured fuel
Works without wearing proper protective gear could re- Should fuel leak from a fuel injection pipe, do not touch
sult in serious injuries. the spouting fuel directly.
Use of tools optimum for each work Fuel in the fuel injection pipes are under high pressure.
Always keep in mind to select most appropriate tools If high-pressured fuel comes into contacts with your
for the work to be performed and use them correctly. If skin, it could penetrate through the skin and may result
tools are damaged, replace with new tools. in gangrene.

IX
 GENERAL CONTENTS

Group Name Contents Group No.

External view
System flow diagrams
General Engine serial number location 1
Main specifications
Tips on disassembling and reassembling
Maintenance service data
Service data 2
Tightening torque table
Service tools Special tool 3
Determining overhaul timing
Determination of overhaul 4
Testing compression pressure
Disassembling and inspecting cylinder head and valve mechanism
Disassembling and inspecting flywheel
Disassembly of basic engine 5
Disassembling and inspecting gear case, timing gear and camshaft
Disassembling and inspecting piston, connecting rod, crankshaft and crankcase
Inspecting and repairing cylinder head and valve mechanism
Inspection and repair of basic Inspecting and repairing flywheel
6
engine Inspecting and repairing timing gear and camshaft
Inspecting and repairing piston, connecting rod, crankshaft and crankcase
Reassembling piston, connecting rod, crankshaft and crankcase
Reassembling timing gear and camshaft
Reassembly of basic engine 7
Reassembling flywheel
Reassembling cylinder head and valve mechanism
Removing fuel system
Fuel system Disassembling, inspecting and reassembling fuel system 8
Installing fuel system
Removing lubrication system
Lubrication system Disassembling, inspecting and reassembling lubrication system 9
Installing lubrication system
Removing cooling system
Cooling system Disassembling, inspecting and reassembling cooling system 10
Installing cooling system
Removing inlet and exhaust systems
Inlet and exhaust systems Disassembling, inspecting and reassembling inlet and exhaust systems 11
Installing inlet and exhaust systems
Removing electrical system
Electrical system Disassembling, inspecting and reassembling electrical system 12
Installing electrical system
Adjusting engine
Adjustment and operation Break-in operation 13
Performance test (JIS standard)