The information in this manual is not all inclusive and cannot take into
account all unique situations. Note that some illustrations are typical and
may not reflect the exact arrangement of every component installed on a
specific chassis.
The information, specifications, and illustrations in this publication are
based on information that was current at the time of publication. Note that
illustrations and instructions are based on information that is subject to
change as new engine/chassis development continues.
No part of this publication may be reproduced, stored in a retrieval
system, or be transmitted in any form by any means including (but not
limited to) electronic, mechanical, photocopying, recording, or otherwise
without prior written permission of Mack Trucks, Inc.
Cautionary signal words (Danger-Warning-Caution) may appear in various locations throughout this
manual. Information accented by one of these signal words must be observed to minimize the risk of
personal injury to service personnel, or the possibility of improper service methods which may damage
the vehicle or cause it to be unsafe. Additional Notes and Service Hints are used to emphasize areas of
procedural importance and provide suggestions for ease of repair. The following definitions indicate the
use of these advisory labels as they appear throughout the manual:
Danger indicates an unsafe practice that could result in death or serious
personal injury. Serious personal injury is considered to be permanent injury
from which full recovery is NOT expected, resulting in a change in life style.
Warning indicates an unsafe practice that could result in personal injury.
Personal injury means that the injury is of a temporary nature and that full
recovery is expected.
Caution indicates an unsafe practice that could result in damage to the product.
Note indicates a procedure, practice, or condition that must be followed in order for
the vehicle or component to function in the manner intended.
A helpful suggestion that will make it quicker and/or easier to perform a procedure,
while possibly reducing service cost.
Page 2
INTRODUCTION
Service Procedures and Tool Usage
Anyone using a service procedure or tool not recommended in this manual must first satisfy himself
thoroughly that neither his safety nor vehicle safety will be jeopardized by the service method he selects.
Individuals deviating in any manner from the instructions provided assume all risks of consequential
personal injury or damage to equipment involved.
Also note that particular service procedures may require the use of a special tool(s) designed for a
specific purpose. These special tools must be used in the manner described, whenever specified in the
instructions.
1. Before starting a vehicle, always be seated in the driver's seat, place the
transmission in neutral, apply the parking brakes, and push in the clutch
pedal. Failure to follow these instructions could produce unexpected
vehicle movement, which can result in serious personal injury or death.
2. Before working on a vehicle, place the transmission in neutral, set the
parking brakes, and block the wheels. Failure to follow these instructions
could produce unexpected vehicle movement, which can result in serious
personal injury or death.
Engine-driven components such as Power Take-Off (PTO) units, fans and fan
belts, driveshafts and other related rotating assemblies, can be very
dangerous. Do not work on or service engine-driven components unless the
engine is shut down. Always keep body parts and loose clothing out of range
of these powerful components to prevent serious personal injury. Be aware of
PTO engagement or nonengagement status. Always disengage the PTO when
not in use.
Do not work under a vehicle that is supported only by a hydraulic jack. The
hydraulic jack could fail suddenly and unexpectedly, resulting in severe
personal injury or death. Always use jackstands of adequate capacity to
support the weight of the vehicle.
Before towing the vehicle, place the transmission in neutral and lift the rear wheels
off the ground, or disconnect the driveline to avoid damage to the transmission
during towing.
REMEMBER,
SAFETY . . . IS NO ACCIDENT!
Page 3
INTRODUCTION
Mack Trucks, Inc. cannot anticipate every
possible occurrence that may involve a potential
hazard. Accidents can be avoided by recognizing
potentially hazardous situations and taking
necessary precautions. Performing service
procedures correctly is critical to technician safety
and safe, reliable vehicle operation.
The following list of general shop safety practices
can help technicians avoid potentially hazardous
situations and reduce the risk of personal injury.
DO NOT perform any services, maintenance
procedures or lubrications until this manual has
been read and understood.
앫Perform all service work on a flat, level
surface. Block wheels to prevent vehicle
from rolling.
앫DO NOT wear loose-fitting or torn clothing.
Remove any jewelry before servicing
vehicle.
앫ALWAYS wear safety glasses and protective
shoes. Avoid injury by being aware of sharp
corners and jagged edges.
앫Use hoists or jacks to lift or move heavy
objects.
앫NEVER run engine indoors unless exhaust
fumes are adequately vented to the outside.
앫Be aware of hot surfaces. Allow engine to
cool sufficiently before performing any
service or tests in the vicinity of the engine.
앫Keep work area clean and orderly. Clean up
any spilled oil, grease, fuel, hydraulic fluid,
etc.
앫Only use tools that are in good condition,
and always use accurately calibrated torque
wrenches to tighten all fasteners to specified
torques. In instances where procedures
require the use of special tools which are
designed for a specific purpose, use only in
the manner described in the instructions.
앫Do not store natural gas powered vehicles
indoors for an extended period of time
(overnight) without first removing the fuel.
앫Never smoke around a natural gas powered
vehicle.
Page 4
INTRODUCTION
EXPLANATION OF NUMERICAL
CODE
The organization of MACK service manuals has
been upgraded to standardize manual content
according to a reference system based on
component identification. The new reference
system will help link the information contained in
this publication with related information included
in other MACK service/warranty publications,
such as associated service bulletins, warranty
manuals, and MACK Service Labor Time
Standards.
The system is based on a numerical code
first digit of which identifies the general
component grouping as listed here:
GROUP 000 — GENERAL DATA
GROUP 100 — CHASSIS
GROUP 200 — ENGINE
GROUP 300 — CLUTCH, TRANSMISSION,
TRANSFER CASE AND PTO
, the
GROUP 400 — STEERING, AXLES, WHEELS
AND TIRES, DRIVELINE
GROUP 500 — BRAKES, AUXILIARY SYSTEMS
GROUP 600 — CAB, TRUCK BODY
GROUP 700 — ELECTRICAL
The second two digits of the three-digit code are
used to identify the system, assembly or
subassembly, as appropriate, within each of the
groupings. The codes applicable to this
publication are shown at the beginning of each
procedure, as necessary, to guide you to specific
component information.
Additionally, a two-character alpha code
[NV] RINGS, PISTON) may be referenced with
each procedure. This alpha code, in combination
with the three-digit Group number, identifies the
specific assembly, sub-assembly or part, and
directly relates to the first five positions of the
operation code listed in MACK Service Labor
Time Standards.
Pound Feet (lb-ft)toKilograms Force per Meter (kgfm)0.13825
Newton Meters (N•m)toPound Inches (lb-in)8.851
Newton Meters (N•m)toPound Feet (lb-ft)0.7376
Newton Meters (N•m)toKilograms Force per Meter (kgfm)0.10197
Kilograms Force per Meter (kgfm)toPound Feet (lb-ft)7.233
Kilograms Force per Meter (kgfm)toNewton Meters (N•m)9.807
Radiator Specific Heat Dissipation Calculations
British Thermal Unit per Hour (BTU/hr)toKilowatt per Degree Celsius (kW/°C)0.000293
Kilowatt per Degree Celsius (kW/°C)toBritish Thermal Unit per Hour (BTU/hr)3414.43
Temperature Calculations
Degrees Fahrenheit (°F)toDegrees Celsius (°C)(°F − 32) x 0.556
Degrees Celsius (°C)toDegrees Fahrenheit (°F)(1.8 x °C) + 32
Page 7
INTRODUCTION
Conversion UnitsMultiply By:
Pressure Calculations
Atmospheres (atm)toBars (bar)1.01325
Atmospheres (atm)toKilopascals (kPa)101.325
Bars (bar)toAtmospheres (atm)0.98692
Bars (bar)toKilopascals (kPa)100
Bar (bar)toPounds per Square Inch (psi)14.5037
Inches of Mercury (in Hg)toKilopascals (kPa)3.377
Inches of Water (in H2O)toKilopascals (kPa)0.2491
Pounds per Square Inch (psi)toKilopascals (kPa)6.895
Pounds per Square Inch (psi)toBar (bar)0.06895
Kilopascals (kPa)toAtmospheres (atm)0.00987
Kilopascals (kPa)toInches of Mercury (in Hg)0.29612
Kilopascals (kPa)toInches of Water (in H2O)4.01445
Kilopascals (kPa)toPounds per Square Inch (psi)0.145
Power Calculations
Horsepower (hp)toKilowatts (kW)0.74627
Kilowatts (kW)toHorsepower (hp)1.34
Fuel Performance Calculations
Miles per Gallon (mile/gal)toKilometers per Liter (km/L)0.4251
Kilometers per Liter (km/L)toMiles per Gallon (mile/gal)2.352
Velocity Calculations
Miles per Hour (mile/hr)toKilometers per Hour (km/hr)1.609
Kilometers per Hour (km/hr)toMiles per Hour (mile/hr)0.6214
Volume Flow Calculations
Cubic Feet per Minute (cu-ft/min)toLiters per Minute (L/min)28.32
Liters per Minute (L/min)toCubic Feet per Minute (cu-ft/min)0.03531
Page 8
INTRODUCTION
ABOUT THE MACK MP8 ENGINE
[200 EA]
1
Figure 1 — MACK MP8 Engine — for Conventional Chassis
The MACK MP8 is a 13 liter (800 CID) engine
with electronic unit injectors, a cooled Exhaust
Gas Recirculation (EGR) system, a Diesel
Particulate Filter (DPF) system and the Holset
Variable Geometry Turbocharger (VGT). The
PowerLeash™ engine brake is optional. The
engine conforms to year 2007 Environmental
Protection Agency (EPA) requirements.
The MP8 EGR system features reduced
restriction plus enhanced efficiency and reliability.
Its venturi system is easy to service.
A DPF system requires elevated exhaust
temperatures. The system uses a diesel oxidation
catalyst, a diesel particulate filter and in-line
reheating of the exhaust gases. The DPF system
removes Particulate Matter (PM) from the
exhaust to conform to the 2007 EPA regulations.
The Holset VGT features fixed vanes with a
sliding nozzle ring. The nozzle position is infinitely
variable between open and closed. This design
reacts quickly to exhaust pressure and controls
inlet pressure more precisely. Reliability is
enhanced by having fewer moving parts. Its
actuator and bearing housing are water cooled
and engine oil lubricated for greater durability.
A wide range of the current transmission
offerings, including manual, automated manual
and automatic, can be teamed with the MP8.
Diagnostic help can be found in the Tech Tool. To
obtain the Tech Tool, contact your local MACK
dealer.
The engine weighs approximately 1160 kg
(2560 lb.) dry (with air compressor, without oil,
coolant, starter, fan, alternator and clutch). Its
design includes a one-piece cylinder head, a
single overhead camshaft, three rocker arms per
cylinder, unit injectors and no pushrods.
PowerLeash™ engine braking, requiring a fourth
rocker arm, is optional. Monosteel™ steel pistons
are made in one piece.
Page 9
INTRODUCTION
Use of ether or similar types of starting aids in
MACK
strictly prohibited. This applies to engines
with or without the electric pre-heater option.
An explosion could occur. Failure to heed this
danger may result in severe personal injury or
death.
®
US07 emission compliant engines is
Fuel passes through two filters, one of which
separates water from the fuel. High-pressure fuel
in the unit injectors is created via the rocker arms
with roller followers in constant, direct contact
with the cams.
Replacing injectors requires a specific procedure,
and installation requires that the EECU be
programmed to recognize replacement injectors.
Cleaning injector bores requires a special tool.
Two optional fan drives are available: On/Off and
electronically actuated. The electronically
actuated viscous fan drive is precisely controlled
by the Engine Electronic Control Unit (EECU).
Timing gears mount on the rear of the MP8
improving the flow of cooling air around the front.
Special service instructions apply to the camshaft
position sensor. The mounting plate, idler and
camshaft gears are marked to facilitate proper
installation. The air compressor drive gear
meshes with the double idler instead of the
auxiliary idler as on the MP7 engine.
Another feature of the MP8 is the rear engine
power take-off (REPTO-ready) that is gear driven
through the timing gear train. An optional PTO
with drive gear, bearing and housing can be
added at the factory.
The rocker arm shaft is held in place by camshaft
bearing capscrews. There are special instructions
for installing the camshaft bearing caps and the
rocker arm shaft during service.
An engine compression brake option on the MP8
engine assists deceleration and braking. The
operation of the brake differs from earlier engine
models. Working in conjunction with the exhaust
cycle, the brake requires a camshaft with four
cams per cylinder, two rocker arms for the
exhaust valve, a bridge over the two exhaust
valves, an electronic control valve and a wiring
harness that includes the control valve. The
exhaust valves are adjusted with shims.
Unique colors and the appearance of the valve
cover, filters and logo labels distinguish the MP8
from other engines in the MACK line.
Preventive maintenance is important to get the
most from the MACK MP8 engine and to ensure
many years of reliable, trouble-free operation.
Refer to the current TS494 Maintenance and
Lubrication manual for schedules and
specifications.
Repair instructions in this manual deal with
removal, installation, disassembly, assembly,
setup and adjustments of MP8 components.
A stiffener plate fastens to the bottom of the
cylinder block to ensure block strength and
rigidity. The engine can be used with axle forward
or axle back vehicles by virtue of optional oil
pans. The engine fan is mounted high or low
depending on vehicle configuration.
The MP8 uses unit injectors. The unit injector
incorporates the pump, valve and injector. Its
internal solenoids permit fast, precise control of
fuel delivery into the cylinder. The unit injectors
are encased by the valve cover and not exposed
to the heat of exhaust system components.
Page 10
There are restrictions concerning the reuse of
certain fasteners. Refer to current specifications
bulletins and the SPECIFICATIONS section of
this manual for detailed information.
INTRODUCTION
Service Precautions Summary
Following is a summary list of the DO and DON’T
issues applying to MP8 engine service.
1. DO NOT machine the cylinder head for
clean-up since this will change injector
depth, thereby affecting emissions. It will
also upset the ability to correctly adjust
timing gear backlash.
2. DO NOT grind the injector copper sleeves.
3. Install the crankshaft main bearing caps
according to marked assembly number.
4. Connecting rod caps MUST BE mated to
their respective connecting rods due to the
“fractured manufacturing” process used.
Also, the rod caps can be installed only one
way because of the difference in spacing
between screw holes at each side of the
cap.
5. DO NOT use the lifting eye on the flywheel
housing when tilting the engine/transmission
assembly to an angle greater than
15 degrees.
6. Cylinder head installation requires lowering
the head onto the gasket using the
alignment screws and washers at the sides
of the head and block. The head must be
pulled back to the mounting plate using
screws inserted through the plate. Pressed
bosses in the gasket keep the head from
making full contact with the gasket surface
and prevent damage to the elastomer
sealing rings as the head slides into
position.
Use of ether or similar types of starting aids in
MACK
strictly prohibited. This applies to engines
with or without the electric pre-heater option.
An explosion could occur. Failure to heed this
danger may result in severe personal injury or
death.
®
US07 emission compliant engines is
7. The MP8 engine uses a number of O-rings
for sealing various fluid joints and tubes. It is
essential that new O-rings of the correct
material be used whenever joints are
disassembled and reassembled.
Page 11
NOTES
Page 12
VISUAL IDENTIFICATION
VISUAL IDENTIFICATION
Page 13
VISUAL IDENTIFICATION
MP8 ENGINE MODEL
IDENTIFICATION
Engine Information Plate
The engine information plate is located on the top
of the cylinder head (valve) cover. This plate
includes information in English and French
concerning the following items.
앫Engine family, model and serial number
앫Displacement, horsepower, fuel rate, idle
speed and engine brake
앫Emissions regulations to which the engine
conforms and other pertinent information
required by emissions regulations
앫Valve lash settings for inlet, exhaust and
engine brake
앫NOx, NMHC+NOx and particulate matter
emissions
앫Exhaust emission control systems
A statement concerning the limitation on the fuel
to be used in the engine also appears.
Code letters under Exhaust Emission Control
Systems represent basic engine systems that
impact emissions. They are taken from the
following list.
앫CAC — Charge Air Cooler
앫DI — Direct Injection
앫DPF — Diesel Particulate Filter
앫EC — Engine Control
앫EGR — Exhaust Gas Recirculation
앫EM — Engine Modification
앫TC — Turbocharger
2
Figure 2 — Engine Information Plate
Engine Serial Number Identification
In addition to the engine information plate on the
cylinder head cover, the engine is also identified
by the engine serial number stamped into the
cylinder block. This serial number is located on
the block left side at the front just below the inlet
manifold.
Page 14
DESCRIPTION AND OPERATION
DESCRIPTION AND OPERATION
Page 15
DESCRIPTION AND OPERATION
MACK MP8 US07 ENGINE DESIGN FEATURES
[200 EA]
3
Figure 3 — MACK MP8 Engine — Conventional Chassis
1. EGR Valve
2. Aftertreatment Fuel Injector
3. Variable Geometry Turbocharger
4. Discharge Recirculation Valve
5. EGR Mixer
6. EGR Cooler Outlet Pipe
7. Thermostat Housing
To accommodate the low cab forward design, the
EGR system and the inlet manifold are configured
differently than for the conventional chassis. The
EGR mixer mounts at the front of the inlet
manifold on the conventional chassis, but near
the rear of the manifold on the low cab forward
design.
8. Differential Pressure Sensors
9. Venturi
10. Coolant Conditioner
11. Full Flow Oil Filters
12. Bypass Oil Filter
13. Starter
14. EGR Cooler
15. EGR Cooler Inlet Pipe
Page 16
DESCRIPTION AND OPERATION
Engine Components
CYLINDER HEAD
4
Figure 4 — Cylinder Head with Valves and Camshaft
Supports
Main features of the cylinder head are:
앫One-piece cast iron
PowerLeash™, the “brake” rocker arm works in
combination with the exhaust rocker arm to
precisely control the opening and closing of the
exhaust valves for engine braking.
5
앫Integral thermostat housing
Separate chambers for exhaust and inlet at each
cylinder make this a “crossflow” design. The fuel
channel, drilled from front to rear, connects with
grooves machined around each injector opening.
A plug at the rear of the cylinder head seals this
channel.
CAMSHAFT AND VALVE TRAIN
The engine has an overhead camshaft and rocker
arm shaft in support of four valves per cylinder.
The camshaft rides on seven journals with a
bearing cap and support block (saddle) at each
point. The bearing inserts (shells), bearing caps
and support blocks are replaceable.
In standard configuration (with VGT exhaust
brake only), there are three cams for each
cylinder, including inlet, injection and exhaust.
There are four cams per cylinder in the optional
configuration (VGT exhaust brake plus
PowerLeash™) with the addition of a “brake” cam
at each cylinder.
The rocker arms are positioned on the shaft (front
to back) in the order of inlet, injector, exhaust and
brake, if so equipped. Both the inlet and exhaust
rocker arms each drive the valve pairs via a
pinless yoke (bridge). On engines equipped with
Figure 5 — Valve Train
1. Inlet Valve Yoke (Bridge)
2. Inlet Valve Rocker Arm
3. Injector Rocker Arm
4. Exhaust Valve Rocker
Arm
5. PowerLeash™ Rocker
Arm
6. Exhaust Valve Yoke
(Bridge)
7. Shim Retaining Screw
Exhaust valve yokes include a shim for
adjustment. Replaceable valve guides and seats
are made of alloyed cast iron and steel
respectively. All valve guides have oil seals.
Exhaust valves have double valve springs.
Rollers in the ends of the rocker arms contact the
cam shaft. The contacts with the yokes have ball
sockets for flexibility.
The camshaft is induction-hardened. Timing
marks for valve and injector adjustment are
located on the flange forward of the No. 1
camshaft journal. These marks are for adjusting
valve clearance. They do not apply to camshaft
timing.
Camshaft thrust washers are integral on the No. 7
journal bearing. Smooth rotation is ensured by
means of a vibration damper on the camshaft
gear. Teeth on the damper interact with the
camshaft position sensor for input to the EECU.
Page 17
DESCRIPTION AND OPERATION
6
Figure 6 — Camshaft and Rocker Arms
1. Engine Brake Cam
2. Exhaust Cam
CYLINDER BLOCK
The cylinder block is made of cast iron. For
increased cylinder block rigidity and noise and
vibration reduction, a steel stiffener plate attaches
to the bottom.
The main and piston lubricating channels are
drilled longitudinally through the block. These are
plugged at the front of the block. The main
channel opens into a cast-in channel that
supplies oil to the timing gears. The piston
cooling channel is covered by the timing gear
cover.
8
3. Injector Cam
4. Inlet Cam
Timing marks on the camshaft provide for valve
and injector adjustment. PowerLeash™ includes
its own electronic control governed by driver's
choice through a switch near the steering wheel.
This control mounts on the cylinder head
between the No. 3 and No. 4 cylinder rocker
arms. The wiring harness includes additional wire
leads for PowerLeash™.
7
Figure 8 — Cylinder Block and Stiffener Plate
1. Cylinder Block2. Block Stiffener Plate
Main bearing caps are made of nodular cast iron
machined together with the cylinder block. Cast
alignment slots in the block and tabs on the caps
ensure proper alignment at installation. Each cap
is marked with its location beginning with No. 1 at
the front. Cap Nos. 4 and 7 are unique and are
not numbered.
The block includes cylinder liners that contact the
coolant directly (wet liners). The casting shape
follows the contours of the cylinders to increase
rigidity and reduce noise.
Figure 7 — MP8 Engine Timing Marks — Camshaft Front
Page 18
End
DESCRIPTION AND OPERATION
Head to Block Alignment
9
Figure 9 — Head to Block Alignment Screws and
Washers
CYLINDER HEAD GASKET
The cylinder head gasket is made of one piece of
sheet steel with vulcanized elastomer seals on oil
and coolant conduits. The design of the engine
and head gasket requires a unique procedure for
installation of the cylinder head.
The screws and washers at the side guide the
head into side-to-side alignment as it is laid on
the gasket and block. Screws passed through the
timing gear plate into the head pull the head into
alignment fore and aft. Small, stamped bosses on
the gasket hold the head clear of the seals and
allow it to glide accurately into position against
the plate during installation. Tightening the head
bolts flattens the bosses on the gasket. For this
reason, a new head gasket must be installed
whenever the head is removed.
10
1. Cylinder Head
2. Alignment Screws and
Washers
3. Cylinder Block
Three screws and washers installed at the side
(two in the block and one in the head) align the
head from side to side at assembly. Fore and aft,
the head is aligned by contact with the timing
gear plate.
The head is aligned with the timing gear plate by
screws passed through the plate into the head
and tightened securely. It is extremely important
to remove these screws before attempting to
remove the cylinder head from the block. Failure
to heed this caution may result in severe damage
to the timing gear plate and other engine
components.
Figure 10 — Cylinder Head Gasket
Page 19
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