John Deere 6.8L PowerTech Diesel Engine Service & Repair Manual
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ii
TABLE OF CONTENTS
Chapter/Section Page
HOW TO USE THIS MANUAL............................................................................................................................. viii
CHAPTER 1 INTRODUCTION ............................................................................................................................. 1-1
Section I GENERAL INFORMATION ...................................................................................................... 1-1
Section II EQUIPMENT DESCRIPTION AND DATA .............................................................................. 1-2
Section III PREPARATION FOR USE ......................................................................................................... 1-8
CHAPTER 2 OPERATING INSTRUCTIONS ....................................................................................................... 2-1
Section I PRINCIPLES OF OPERATION ................................................................................................. 2-1
Section II OPERATING INSTRUCTIONS ................................................................................................. 2-2
Section III SPECIAL INSTRUCTIONS........................................................................................................ 2-2
CHAPTER 3 UNIT MAINTENANCE INSTRUCTIONS ...................................................................................... 3-1
Section I LUBRICATION INSTRUCTIONS ............................................................................................. 3-1
Section II REPAIR PARTS; TOOLS; SPECIAL TOOLS;
TEST, MEASUREMENT AND DIAGNOSTIC (TMDE); AND SUPPORT EQUIPMENT .... 3-1
Section III PREVENTIVE MAINTENANCE CHECKS AND SERVICES (PMCS) ................................... 3-1
Section IV TROUBLESHOOTING............................................................................................................... 3-3
Section V MAINTENANCE PROCEDURES.............................................................................................. 3-15
CHAPTER 4 DIRECT SUPPORT MAINTENANCE INSTRUCTIONS............................................................... 4-1
Section I TROUBLESHOOTING............................................................................................................... 4-1
Section II MAINTENANCE PROCEDURES.............................................................................................. 4-14
CHAPTER 5 GENERAL SUPPORT MAINTENANCE INSTRUCTIONS........................................................... 5-1
Section I TROUBLESHOOTING............................................................................................................... 5-1
Section II MAINTENANCE PROCEDURES ................................................................................................ 5-1
Appendix A References .................................................................................................................................... A-1
Appendix B Maintenance Allocation Chart (MAC) ......................................................................................... B-1
Appendix C Components of End Item and Basic Issue Items List ................................................................... C-1
Appendix D Additional Authorization List ...................................................................................................... D-1
Appendix E Expendable and Durable Items List ............................................................................................. E-1
Appendix F Illustrated List of Manufactured Items ......................................................................................... F-1
Appendix G Torque Limits............................................................................................................................... G-1
Appendix H Mandatory Replacement Parts ..................................................................................................... H-1
Alphabetical Index ................................................................................................................................................... Index-1
iii
LIST OF ILLUSTRATIONS
Figure Page
Figure 1-1. Engine Components ....................................................................................................................... 1-4
Figure 1-2. Option Code Label ......................................................................................................................... 1-5
Figure 3-1. Thermostat and Water Manifold/Thermostat Cover ...................................................................... 3-19
Figure 3-2. Thermostat Installation .................................................................................................................. 3-21
Figure 3-3. Water Pump Assembly................................................................................................................... 3-22
Figure 3-4. Battery Charging Alternator and Mounting ................................................................................... 3-24
Figure 3-5. Starter Solenoid Test Circuit .......................................................................................................... 3-25
Figure 3-6. Starter Assembly ............................................................................................................................ 3-27
Figure 3-7. Intake Manifold.............................................................................................................................. 3-28
Figure 3-8. Exhaust Manifold ........................................................................................................................... 3-29
Figure 3-9. Oil Filter Assembly ........................................................................................................................ 3-30
Figure 3-10. Oil Cooler Assembly...................................................................................................................... 3-32
Figure 3-11. Oil Fill Tube Assembly .................................................................................................................. 3-33
Figure 3-12. Oil Dipstick Tube Assembly .......................................................................................................... 3-34
Figure 3-13. Oil Dipstick Tube Installation ........................................................................................................ 3-35
Figure 3-14. Oil Pan ........................................................................................................................................... 3-36
Figure 3-15. Fuel Filter Assembly ...................................................................................................................... 3-39
Figure 3-16. Fuel Supply Pump .......................................................................................................................... 3-40
Figure 3-17. Fuel Injection Assembly ................................................................................................................ 3-41
Figure 4-1. Battery Charging Alternator Test Circuit ....................................................................................... 4-14
Figure 4-2. Battery Charging Alternator Assembly .......................................................................................... 4-16
Figure 4-3. Stator and Rear Housing Separation .............................................................................................. 4-17
Figure 4-4. Testing Brush Assembly ................................................................................................................ 4-17
Figure 4-5. Testing Exciting Diodes ................................................................................................................. 4-18
Figure 4-6. Testing Positive/Negative Diodes .................................................................................................. 4-18
Figure 4-7. Testing Stator Windings................................................................................................................. 4-19
Figure 4-8. Testing Rotor ................................................................................................................................. 4-20
Figure 4-9. Starter Bench Test Setup................................................................................................................ 4-22
Figure 4-10. Starter Assembly ............................................................................................................................ 4-23
Figure 4-11. Disconnecting Lead Wire (Typical) ............................................................................................... 4-24
Figure 4-12. Removing Through Bolts (Typical) ............................................................................................... 4-24
Figure 4-13. Removing Starter End Frame and Yoke Assembly (Typical) ........................................................ 4-25
Figure 4-14. Removing Brushes ......................................................................................................................... 4-25
Figure 4-15. Removing Armature ....................................................................................................................... 4-26
Figure 4-16. Removing Housing (Typical) ......................................................................................................... 4-26
Figure 4-17. Removing Overrunning Clutch (Typical)....................................................................................... 4-27
Figure 4-18. Removing Steel Ball ...................................................................................................................... 4-27
Figure 4-19. Removing Pinion, Retainer, and Rollers (Typical) ........................................................................ 4-28
Figure 4-20. Removing Washer and Spring........................................................................................................ 4-28
Figure 4-21. Checking Commutator Run-Out..................................................................................................... 4-29
Figure 4-22. Measuring Commutator OD........................................................................................................... 4-29
Figure 4-23. Measuring Segment Mica Depth .................................................................................................... 4-30
Figure 4-24. Inspecting and Replacing Bearings ................................................................................................ 4-30
Figure 4-25. Measuring Brush Length ................................................................................................................ 4-31
iv
LIST OF ILLUSTRATIONS (CONTINUED)
Figure Page
Figure 4-26. Checking Overrunning Clutch........................................................................................................ 4-31
Figure 4-27. Growler Test .................................................................................................................................. 4-32
Figure 4-28. Testing for Grounded Windings..................................................................................................... 4-32
Figure 4-29. Checking for Open Circuit Windings............................................................................................. 4-33
Figure 4-30. Checking Brush Holder Assembly ................................................................................................. 4-33
Figure 4-31. Checking Field Coils...................................................................................................................... 4-34
Figure 4-32. Checking for Open Field Coil ........................................................................................................ 4-34
Figure 4-33. Installing Brushes........................................................................................................................... 4-35
Figure 4-34. Installing Cover On Yoke .............................................................................................................. 4-36
Figure 4-35. Installing Yoke ............................................................................................................................... 4-36
Figure 4-36. Turbocharger.................................................................................................................................. 4-39
Figure 4-37. Turbocharger Inspection Points ..................................................................................................... 4-40
Figure 4-38. Inspecting Turbocharger Bearings ................................................................................................. 4-43
Figure 4-39. Oil Pressure Regulating Valve Assembly ...................................................................................... 4-47
Figure 4-40 Pick-Up Tube Assembly ................................................................................................................ 4-49
Figure 4-41. Separating Gear and Shaft.............................................................................................................. 4-52
Figure 4-42. Check Timing Marks ..................................................................................................................... 4-53
Figure 4-43. Fuel Injection Pump Pressure Outlet Ports .................................................................................... 4-55
Figure 4-44. Fuel Injection Nozzle Assembly ................................................................................................... 4-59
Figure 4-45. Rocker Arm Cover ......................................................................................................................... 4-65
Figure 4-46. Engine Timing Hole Location........................................................................................................ 4-66
Figure 4-47. Rocker Arm Location..................................................................................................................... 4-67
Figure 4-48. Rocker Arm Assembly ................................................................................................................... 4-70
Figure 4-49. Cylinder Head Assembly ............................................................................................................... 4-75
Figure 4-50. Fuel Transfer Pump Push Rod Location ........................................................................................ 4-76
Figure 4-51. Valve Recess Measurement ........................................................................................................... 4-76
Figure 4-52. Cylinder Head Capscrew Torque Sequence ................................................................................... 4-79
Figure 4-53 Flywheel Flatness ........................................................................................................................... 4-82
Figure 4-54. Flywheel Removal ......................................................................................................................... 4-82
Figure 4-55. Flywheel Ring Gear ....................................................................................................................... 4-83
Figure 4-56. Removal of Rear Crankshaft Oil Seal ............................................................................................ 4-84
Figure 4-57. Rear Crankshaft Oil Seal Installation ............................................................................................. 4-86
Figure 4-58. Flywheel and Housing Assembly ................................................................................................... 4-88
Figure 4-59. Gasket Application to Cylinder Block ........................................................................................... 4-89
Figure 4-60. Crankshaft Pulley ........................................................................................................................... 4-91
Figure 4-61. Fan Drive Assembly....................................................................................................................... 4-93
Figure 4-62. Timing Gear Cover ........................................................................................................................ 4-95
Figure 4-63. Engine Lifting ................................................................................................................................ 4-100
Figure 5-1. Fuel Injection Pump ....................................................................................................................... 5-6
Figure 5-2. Clip Removal ................................................................................................................................. 5-9
Figure 5-3. Droop Control Locking Cap Removal ........................................................................................... 5-9
Figure 5-4. Control Rod Assembly and Governor Spring Removal ................................................................. 5-10
Figure 5-5. Cam Advance Pin Removal ........................................................................................................... 5-11
Figure 5-6. Reed Valve Removal. .................................................................................................................... 5-11
Figure 5-7. Linkage Hook Disconnection......................................................................................................... 5-12
Figure 5-8. Hydraulic Head Assembly Removal. ............................................................................................. 5-12
v
LIST OF ILLUSTRATIONS (CONTINUED)
Figure Page
Figure 5-9. Governor Arm and Linkage Hook Removal .................................................................................. 5-13
Figure 5-10. Drive Shaft Bearing and Seal Removal (Shown Removed) .......................................................... 5-14
Figure 5-11. Transfer Pump End Cap Seal Removal (Typical). ......................................................................... 5-14
Figure 5-12. Cam Ring Removal. ....................................................................................................................... 5-15
Figure 5-13. Pumping Plunger Removal............................................................................................................. 5-15
Figure 5-14. Delivery Valve Removal ................................................................................................................ 5-16
Figure 5-15. Retaining Clip Removal ................................................................................................................. 5-16
Figure 5-16. Fuel Injection Housing ................................................................................................................... 5-17
Figure 5-17. Drive Shaft ..................................................................................................................................... 5-18
Figure 5-18. Cam Ring ....................................................................................................................................... 5-19
Figure 5-19. Hydraulic Head Assembly (Typical) .............................................................................................. 5-20
Figure 5-20. Distributor Rotor Assembly (Typical) ........................................................................................... 5-20
Figure 5-21. Shoes and Rollers........................................................................................................................... 5-21
Figure 5-22. Leaf Springs ................................................................................................................................... 5-21
Figure 5-23. Transfer Pump Blades .................................................................................................................... 5-22
Figure 5-24. Transfer Pump Liner ...................................................................................................................... 5-23
Figure 5-25. Transfer Pump Regulating Piston and Adjusting Screw ................................................................ 5-23
Figure 5-26. Transfer Pump Regulator Assembly .............................................................................................. 5-24
Figure 5-27. Metering Valve and Arm Assembly ............................................................................................... 5-25
Figure 5-28. Delivery Valve ............................................................................................................................... 5-25
Figure 5-29. Fuel Side Seal Installation.............................................................................................................. 5-26
Figure 5-30. Oil Side Seal Installation................................................................................................................ 5-27
Figure 5-31. Drive Shaft Bearing Installation..................................................................................................... 5-27
Figure 5-32. Seal Protection Tube ...................................................................................................................... 5-28
Figure 5-33. Thrust Bearing and Thrust Washer ................................................................................................ 5-28
Figure 5-34. Spring Washer and Retaining Ring ............................................................................................... 5-29
Figure 5-35. Timing Mark Locator ..................................................................................................................... 5-29
Figure 5-36. Weight Retaining Assembly........................................................................................................... 5-30
Figure 5-37. Tightening Delivery Valve Stop Screw.......................................................................................... 5-30
Figure 5-38. Pumping Plunger Installation ......................................................................................................... 5-31
Figure 5-39. Installing Rollers and Shoes (Typical) ........................................................................................... 5-31
Figure 5-40. Measuring Roller to Roller Dimension .......................................................................................... 5-32
Figure 5-41. Transfer Pump Liner Installation (Typical).................................................................................... 5-33
Figure 5-42. Transfer Pump Blade Installation (Typical) ................................................................................... 5-33
Figure 5-43. Regulator Assembly Installation (Typical) .................................................................................... 5-34
Figure 5-44. Governor Weight Installation (Typical) ......................................................................................... 5-35
Figure 5-45. Thrust Washer Installation (Typical) ............................................................................................. 5-35
Figure 5-46. Thrust Sleeve Installation (Typical) ............................................................................................... 5-36
Figure 5-47. Head and Rotor Assembly Installation (Typical) ........................................................................... 5-36
Figure 5-48. Control Spring Installation ............................................................................................................. 5-37
Figure 5-49. Control Rod Installation................................................................................................................. 5-38
Figure 5-50. Droop Control Locking Cap Installation........................................................................................ 5-38
Figure 5-51. Damper Barrel and Piston .............................................................................................................. 5-39
Figure 5-52. Throttle Installation........................................................................................................................ 5-39
Figure 5-53. Setting Governor Linkage Gap ...................................................................................................... 5-40
Figure 5-54. Reed Valve Assembly .................................................................................................................... 5-41
Figure 5-55. Piston and Piston Ring Seal ........................................................................................................... 5-41
Figure 5-56. Piston Ring..................................................................................................................................... 5-42
vi
LIST OF ILLUSTRATIONS (CONTINUED)
Figure Page
Figure 5-57. Piston Ring Compressor................................................................................................................. 5-42
Figure 5-58. Piston in Power Side Piston Hole .................................................................................................. 5-43
Figure 5-59. Power Side Piston Hole Plug Installation ...................................................................................... 5-43
Figure 5-60. Aligning Pin Hole in Piston ........................................................................................................... 5-44
Figure 5-61. Camshaft ........................................................................................................................................ 5-47
Figure 5-62. Measuring Camshaft Lobe Height ................................................................................................. 5-50
Figure 5-63. Idler Gears ..................................................................................................................................... 5-55
Figure 5-64. Spring Pin Protrusion ..................................................................................................................... 5-56
Figure 5-65. Front Plate...................................................................................................................................... 5-57
Figure 5-66. Front Plate Sealant Application ..................................................................................................... 5-59
Figure 5-67. Crankshaft and Main Bearings ....................................................................................................... 5-60
Figure 5-68. Critical Areas of Crankshaft Load Stress ....................................................................................... 5-63
Figure 5-69. Measuring Main Thrust Journal and Thrust Bearing Width........................................................... 5-65
Figure 5-70. Fastening Cylinder Liners .............................................................................................................. 5-71
Figure 5-71. Removing Carbon From Cylinder Liners ....................................................................................... 5-71
Figure 5-72. Pistons, Connecting Rods and Cylinder Liners .............................................................................. 5-74
Figure 5-73. Piston Inspection (Defects Exaggerated) ....................................................................................... 5-75
Figure 5-74. Checking Piston Keystone Ring Groove Wear .............................................................................. 5-75
Figure 5-75. Measuring Piston Ring Groove Clearance ..................................................................................... 5-76
Figure 5-76. Measuring Piston Skirt ................................................................................................................... 5-76
Figure 5-77. Measuring Rod Center-to-Center Bores ........................................................................................ 5-80
Figure 5-78. Inspecting Cylinder Liner Pitting ................................................................................................... 5-85
Figure 5-79. Inspecting Piston Cooling Orifice .................................................................................................. 5-92
Figure 5-80. Oil Gallery Plugs............................................................................................................................ 5-92
Figure 5-81. Inspecting Cylinder Block.............................................................................................................. 5-94
Figure 5-82. Measuring Main Bearing Bore ....................................................................................................... 5-95
Figure 5-83. Measuring Cam Follower Bore Diameter ...................................................................................... 5-95
Figure 5-84. Measuring Camshaft Bore Diameter .............................................................................................. 5-96
Figure 5-85. Measuring Cylinder Block Top Deck Flatness .............................................................................. 5-96
Figure 5-86. Oil Pump Assembly ....................................................................................................................... 5-99
Figure 5-87. Oil Pump Axial Clearance ............................................................................................................ 5-101
Figure 5-88. Oil Pump Radial Clearance Measurement ..................................................................................... 5-101
Figure 5-89. Oil Bypass Valve. .......................................................................................................................... 5-103
Figure 5-90. Valve Face Angle ........................................................................................................................... 5-106
Figure 5-91. Measuring Cylinder Head Thickness ............................................................................................. 5-108
Figure 5-92. Valve Seat Removal Chisel ............................................................................................................ 5-111
Figure 5-93. Removal of Valve Seat Insert ........................................................................................................ 5-111
Figure 5-94. Valve Seat Bore in Cylinder Head ................................................................................................ 5-112
Figure 5-95. Valve Guide Installation ................................................................................................................ 5-113
vii
LIST OF TABLES
Table Page
Table 1-1. Table of Specifications .................................................................................................................. 1-5
Table 1-2. Engine Option Codes - 6 Cylinder, 6.8 Liter ................................................................................. 1-6
Table 3-1. Preventive Maintenance Checks and Services (PMCS) ................................................................. 3-2
Table 3-2. Unit Troubleshooting ..................................................................................................................... 3-4
Table 4-1. Direct Support Troubleshooting..................................................................................................... 4-2
Table 4-2. Valve Clearance Specification (Rocker Arm-To-Valve Tip) ......................................................... 4-68
Table 4-3. Valve Lift Specifications at 0.00 in. (mm) Valve Clearance .......................................................... 4-69
Table 4-4. Valve Recess Specifications .......................................................................................................... 4-77
Table 4-5. Cylinder Block Top Deck Specifications ....................................................................................... 4-78
Table 4-6. Flywheel Face Flatness Specifications ........................................................................................... 4-82
Table 5-1. Procedural Index for General Support Maintenance ...................................................................... 5-1
Table 5-2. Fuel Injection Pump Checks .......................................................................................................... 5-5
Table 5-3. Camshaft Lobe Height Specifications ............................................................................................ 5-51
Table 5-4. Camshaft and Timing Gear Train Specifications ........................................................................... 5-53
Table 5-5. Crankshaft and Main Bearings Specifications ............................................................................... 5-64
Table 5-6. Connecting Rod Journal and Bearing Specifications ..................................................................... 5-77
Table 5-7. Connecting Rod Bore (Without Bearing Inserts) Specifications.................................................... 5-78
Table 5-8. Connecting Rod Piston Pin Bushing Specifications ....................................................................... 5-79
Table 5-9. Cylinder Liner Height Specifications ............................................................................................. 5-83
Table 5-10. Cylinder Liner Thickness Specifications........................................................................................ 5-87
Table 5-11. Piston and Cylinder Liner Specifications ....................................................................................... 5-87
Table 5-12. Valve Seat Bore Insert Specifications ............................................................................................ 5-113
viii
HOW TO USE THIS MANUAL
In this manual (TM 9-2815-260-24) paragraphs are underlined and sections and chapters appear in capital letters. The
location of additional material that must be referenced is clearly marked. Illustrations in this text are located as close as
possible to their references.
Chapter 1 - INTRODUCTION. This section contains general information, equipment description and data, and principles of
operation for the engine.
Chapter 2 - OPERATING INSTRUCTIONS. This section contains functional descriptions of the engine systems and how
they are connected to the end item. For operation, refer to end item operator's manual.
Chapter 3 - UNIT MAINTENANCE INSTRUCTIONS. This section contains troubleshooting procedures used to recognize
and correct engine malfunctions at the unit level, and all maintenance procedures authorized to be performed on the engine
the unit level.
Chapter 4 - DIRECT SUPPORT MAINTENANCE INSTRUCTIONS. This section contains direct support level
troubleshooting procedures used to recognize and correct engine malfunctions at the direct support level, and all maintenance
procedures authorized to be performed on the engine at the direct support level.
Chapter 5 - GENERAL SUPPORT MAINTENANCE INSTRUCTIONS. This section contains general support maintenance
instructions which are limited to the disassembly, cleaning, inspection and assembly of components after troubleshooting has
already been accomplished.
APPENDICES.
Appendix A lists all forms, field manuals, technical manuals and miscellaneous publications referenced in this manual and
should be used in conjunction with this manual.
Appendix B is the Maintenance Allocation Chart (MAC) which designates all maintenance and repair functions authorized to
be performed at the different maintenance levels.
Appendix C lists the Components of End Item (COEI) and Basic Issue Items (BII) lists.
Appendix D. Refer to End Item Maintenance Manual Appendix D for lists of items authorized for use with the generator set,
but not issued with it or supported by generator set engineering drawings.
Appendix E lists expendable supplies and materials required to operate and maintain the generator set. These items are
authorized by CTA 50-970, Expendable Items (except medical, Class V, repair parts, and heraldic items).
Appendix F includes complete instructions for fabricating or assembling parts as required for the engine.
Appendix G provides torque limits for fasteners used in maintenance of the engine.
Appendix H lists parts that must be replaced if removed during maintenance.
1-1
CHAPTER 1
INTRODUCTION
Section I. GENERAL INFORMATION
1.1. SCOPE.
a. Type of Manual. This manual contains unit, direct support, and general support maintenance
instructions for the Model TO6068TF151 Diesel Engine, hereafter referred to as engine. Also
included are descriptions of major systems/components and their functions in relation to other
systems/components.
b. Purpose of Equipment. The engine provides a driving force for generators or other equipment
requiring this size (HP rating) and compatibility.
1.2. MAINTENANCE FORMS, RECORDS, AND REPORTS .
a. Reports of Maintenance and Unsatisfactory Equipment. Department of the Army forms and
procedures used for equipment maintenance will be those prescribed by DA Pam 738-750, Army
Maintenance Management System (TAMMS). Air Force personnel will use AFR 66-1, Air Force
Maintenance Management Policy, for maintenance reporting and TO-OO-35D54 for unsatisfactory
equipment reporting.
b. Reporting of Item and Packaging Discrepancies. Fill out and forward SF 364 (Report of
Discrepancy (ROD)) as prescribed in AR 735-1l-2/DLAR 414-55/SECNAVINST 4355.18/AFR
400-54/MCO 4430.3J.
c. Transportation Discrepancy Report (TDR) (SF 361). Fill out and forward Transportation
Discrepancy Report (TDR) (SF361) as prescribed in AR 55-38/NAVSUPINST 4610.33C/AFR 75-
18/MCO P4610.19D/DLAR 4500.15.
1.3. REPORTING EQUIPMENT IMPROVEMENT RECOMMENDATIONS (EIR).
Army - If your equipment needs improvement, let us know. Send us an EIR. You, the user, are the only
one who can tell us what you don’t like about your equipment. Let us know why you don’t like the design
or performance. Put it on a SF 368 (Product Quality Deficiency Report). Mail it to us at the address below.
We’ll send you a reply. The fax number is 908-532-1413, DSN 992-1413. You may also e-mail your
recommendations to AMSEL-LC-LEO-PUBS-CHG@cecom3.monmouth.army.mil.
Commander
U.S. Army Communications and Electronics Command (CECOM)
ATTN: AMSEL-LC-LEO-D-CS-CFO
Fort Monmouth, New Jersey 07703-5008
(AF) USAF Deficiency Reporting and Investigating System, TO 00-35D-54, Appendix A procedures
will be used for electronic submission. Submit mailed forms to:
SMALC/LHCABD
5029 Dudley Boulevard
McClellan AFB, CA 95652-1095
1-2
(MC) Quality Deficiency Reports (QDR) shall be submitted on SF 368 in accordance with MCO
4855.10. Submissions may also be made using NAVMC Form 10772. Submit directly to:
Commander
Marine Corps Logistics Bases
(Code 856)
Albany, GA 31704-5000
A reply will be furnished to you.
1.4. DESTRUCTION OF ARMY MATERIAL TO PREVENT ENEMY USE.
Refer to TM 750-244-3 for procedures to destroy equipment to prevent enemy use.
1.5. CORRISION PREVENTION AND CONTROL.
Refer to Corrosion and Corrosion Prevention: Metals, MIL-HDBK-729.
1.6. PREPARATION FOR STORAGE OR SHIPMENT.
Refer to TB 740-97-2 for procedures to place the equipment into storage.
1.7. WARRANTY.
The engine is warranted for a specific period of time. Refer to Warranty Technical Bulletin for the end item. The
warranty begins from the date stamped on the data plate. Report all defects in material or workmanship to your
supervisor, who will take appropriate action.
Section II. EQUIPMENT DESCRIPTION AND DATA
1.8. GENERAL.
The diesel engine (Figure 1-1) is six cylinder, four cycle, fuel injected, turbocharged, and liquid cooled. The firing
order is 1-5-3-6-2-4. The number one cylinder is toward the fan end of the engine. The serial number is found on
top of valve cover. Rotation of engine is counterclockwise as viewed from rear of engine facing forward.
NOTE
All locations referenced herein are given from rear of engine facing forward.
1.9. DETAILED DESCRIPTION.
a. Turbocharger. A turbocharger, operated by exhaust gases, compresses intake air and routes it to the
combustion chamber.
b. Camshaft. The camshaft is driven by an intermediate gear in the timing gear train which meshes with the
crankshaft gear. Camshaft rotates in honed machined bores in cylinder block; no bushings are used. The
camshaft lobes determine the time and rate of opening of each valve and actuates the fuel supply pump.
1-3
c. Intake and Exhaust Valves. Intake and exhaust valves are operated by cam followers, push rods, and
rocker arm assembly. Valve seat inserts in cylinder head are used for intake and exhaust valves.
d. Crankshaft. The crankshaft is a one-piece, heat treated, steel forging which operates in replaceable two-
piece main bearings. The rear thrust bearing has a flange on each side to support crankshaft thrust and to limit
end play.
e. Cylinder Liners and Pistons. Cylinder liners are "wet" (surrounded by coolant) and are individually
replaceable. O-rings are used to seal the connection between cylinder block and liners. Pistons are made of
cast high-grade aluminum alloy with internal ribbing. The skirt is cam ground to allow for expansion when
heated during operation. The piston crown has a cut-out swivel cup with a truncated cone in the center. Two
compression rings and one oil control ring are used. The top compression ring is a keystone type ring. All
piston rings are located above the piston pin. The hardened piston pins are fully-floating and held in position
by means of retainer rings. Spray jets (piston cooling orifices) in cylinder block direct pressurized oil to
lubricate piston pins and cool pistons. Connecting rods are forged steel and have replaceable bushing and
bearing inserts.
f. Cooling System. The cooling system consists of a radiator, water pump, cooling fan, thermostat, and
connecting hoses. The fan and water pump are both belt driven from the crankshaft pulley. The thermostats
control engine temperature and are installed in top of engine. The function of the cooling system is to
maintain a specific operating temperature of 180 to 220°F (82 to 104°C) for the engine.
g. Lubrication System. The lubrication system consists of oil pan (sump), a gear type pump, full flow
spin-on oil filter with built-in bypass valve, oil cooler with built-in bypass valve, pressure regulating
valve, bypass valve, and the internal passages.
h. Fuel System. The function of the fuel system is to inject a metered quantity of clean atomized fuel
into the engine cylinders at a precise time near the end of the compression stroke of each piston. The
fuel system consists of the fuel tank, fuel filter/water separator, fuel supply pump, fuel injection pump,
and the fuel injectors. The fuel tank is not mounted on the engine. The fuel supply pump is mounted to
the block and is driven by the camshaft. The fuel injection pump is mounted on the front plate and is
driven by an intermediate gear in the timing gear train meshing with crankshaft gear.
i. Electrical System. The electrical system is 28VDC operation and consists of a battery charging
alternator, starter, externally mounted batteries, and other items as required. The battery charging
alternator is mounted on front of engine and is belt driven. When engine is operating, the battery
charging alternator supplies 28VDC to recharge the batteries and maintain them at a full state of charge.
The starter is mounted on the flywheel housing, and when energized, engages the ring gear of the
flywheel to rotate the engine.
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John Deere 6.8L PowerTech Diesel Engine Service & Repair Manual
Engine Covered:
- John Deere 6.8L PowerTech, Model 6068TF151
- 6-Cylinder, 4-Cycle, Fuel Injected, Turbocharged
- Mechanically Injected (Stanadyne DB4 Pump), Non-EGR
- EPA Tier 1 / Early Tier 2 Emissions Compliant
Important Note on Engine Compatibility: This is a highly specific manual for the mechanically injected, non-EGR 6068TF151 engine. It does not cover newer, electronically controlled common-rail engines equipped with EGR systems (Tier 3 and later). Please verify your engine model and fuel system before purchase.
The John Deere 6.8L PowerTech (6068TF151) Diesel Engine Service & Repair Manual (TM 9-2815-260-24) is the official U.S. Army Technical Manual for this specific workhorse engine. This is a complete and unabridged military document that provides the exact standards for operation, troubleshooting, maintenance, and depot-level overhaul.
Structured for military echelons of maintenance, this manual offers a unique and incredibly detailed approach to engine service. It is the definitive resource for any technician, fleet manager, or owner requiring the most comprehensive information available for the mechanically-injected 6068TF151 engine.
What’s Inside This John Deere 6.8L Technical Manual
Unit & Direct Support Maintenance
Provides the official procedures for field-level service. This includes routine maintenance instructions (PMCS), advanced troubleshooting symptom charts, and in-chassis repair procedures for replacing external components without removing the engine from the equipment.
General Support Maintenance - Complete Engine Overhaul
This is the core overhaul section of the manual, providing depot-level, step-by-step instructions for a full engine teardown and rebuild. It covers the full disassembly, cleaning, precision measurement, inspection of all wear parts, and reassembly of the entire engine from the bare block up.
Mechanical Fuel System (Stanadyne DB4)
Provides detailed service and adjustment procedures for the Stanadyne Model DB4 mechanical injection pump and associated fuel system components. This section is critical for correctly timing and tuning this robust, non-electronic engine.
Detailed Appendices & Technical Data
A wealth of professional-grade data is included in the appendices. This includes a full Maintenance Allocation Chart (MAC), lists of expendable/durable items, detailed torque limits for every fastener on the engine, and a list of mandatory replacement parts for a proper overhaul.
Why Choose This Official Technical Manual?
The difference between a mechanically injected, non-EGR engine and a modern common-rail engine is night and day. This manual is essential because it provides the correct, specific procedures for the older, more robust 6068TF151. It contains the exact specifications and troubleshooting charts needed to service these engines, information that is simply not present in manuals for later, emissions-compliant powerplants.
Digital Format & Compatibility
Delivered as a high-resolution, fully searchable PDF, this manual works seamlessly on Windows, macOS, iOS, Android, and Linux systems. It is ideal for use on a workshop computer, tablet, or can be printed for hands-on reference right at the engine stand.
Get Your John Deere 6068TF151 Manual Today
Empower your workshop with the same data used by U.S. Army mechanics. Whether you're performing field maintenance or a complete depot-level rebuild, this is the ultimate and only resource for the 6068TF151 engine.
Printable: Yes
Language: English
Publication Number: TM 9-2815-260-24
Compatibility: Windows, macOS, Linux, iOS, Android
Requirements: PDF Reader
