Detroit Diesel V71 Series Torque Specifications

June 9, 2023
12V71 Detroit Diesel Engine
12V71 Detroit Diesel Engine

Following torque specifications for Detroit Diesel V71 engines is critical to ensure proper assembly, optimal performance, and engine longevity. These specifications are carefully designed to provide the correct amount of clamping force for components, such as cylinder heads, connecting rods, and main bearings. Over-tightening bolts can lead to component damage, warping, or cracking, while under-tightening may result in leaks, loss of compression, or parts loosening during operation. Adhering to the recommended torque specs minimizes the risk of mechanical failures, supports engine efficiency, and upholds safety standards, especially in demanding applications where reliability is paramount.

For Additional Information On Servicing A Detroit Diesel V71 Engines Look At The Links Below

The Practical Guide To Servicing Your Detroit Diesel V71 Engine

Comprehensive FAQs About Servicing Your Detroit Diesel V71 Engine

Parts For Detroit Diesel Engines

Detroit Diesel V71 Series Torque Specifications
Thread Size (in.)
Description
 Torque Specifications
lb-ft N-m
1 1/8-18 Nut-Cam and Balance Shaft 300-325 407-441
1/4-18 NPTF Dipstick Adaptor used with Airbox Drain Banjo 38-42 52-57
1/4-20
 Standard Torque Specification 7-9 9-12
Bolt-Injector Control Shaft Bracket 10-17 14-23
Bolt-Cam Follower Guide 12-16 16-22
1/4-28
 Standard Torque Specification 8-10 11-14
Screw Inj. Rack Control Lever 2-3 3-4
5/16-18
 Standard Torque Specification 13-17 18-23
Bolt Blower Drive Assembly Thrust Collar 16-2 22-28
Bolt-Hand Hole Cover (Air Box) 13-21 18-28
Bolt-Oil Pan (Cast) – Hard Gasket 13-21 18-28
Bolt-Oil Pan (Low Pan or in Aluminum F/W Hsg. and Front Cover) 10-12 14-16
5/16-24
 Standard Torque Specification 15-19 20-26
Nut-Lock Push Rod 15-19 20-26
Bolt-Blower Drive Plat to Gear 25-30 34-41
Bolt-Blower Drive Coupling Rotor Gear 20-25 27-34
Nut-Lock Valve Bridge Adj. Screw 20-25 27-34
3/8-16
 Standard Torque Specification 30-35 41-47
Bolt-Camshaft & Seal End Bearing 35-40 47-54
Bolt-Air Inlet Housing to Blower 16-21 22-28
Bolt-Trunnion to Block 40-45 54-61
Bolt-Rocker Cover Hold-Down Special 12-Point 15-20 20-27
Bolt-side Angle Blower Mounting 30-35 41-47
Bolt-Injector Clamp 20-25 27-34
Bolt-Oil Pan 10-20 14-27
3/8-24
 Standard Torque Specification 35-39 47-53
Bolt-Flywheel Housing Small Hole Cover 30-35 41-47
Bolt-Accessory Drive to Balance Gear (Steel Disc) 45-50 61-68
Bolt-Blower Drive Sprocket to Blower Rotor Gear 45-50 61-68
Screw-Lock-Cam Inter Bearing 15-20 20-27
Bolt-Lower Front Cover 25-30 34-41
Nut-Water Manifold 20-25 27-34
Bolt-Blower Drive Assembly Flex Plate to Hub 40-45 54-61
Bolt & Nuts-Blower Drive Assembly Attaching Nuts and Bolts 25-30 34-41
Nut-Flywheel Housing Small Hole Stud 20-25 27-34
Nut-Exhaust Outlet Manifold Flange (Brass) 20-25 27-34
Nut-Plug Blower Drive Assembly and Flywheel Housing Plug Nuts 25-30 34-41
Nut-Flange Mounted Alternator Adaptor 15-20 20-27
Nut-Fuel Jumper Line- O Ring 13-17 18-23
Nut-Fuel Jumper Line – Flared 11-13 15-18
Nut-Injector Clamp 20-25 27-34
7/16-14
 Standard Torque Specification 46-50 62-68
Bolt-Tach. Drive Cover 30-35 41-47
Bolt-Crankshaft Outboard Main Bearing 70-75 95-102
Bolt-Flywheel Housing Large Hole Cover 30-35 41-47
Bolt-Blower End Plate 40-45 54-61
7/16-20
 Standard Torque Specification 57-61 77-83
Connector-Fuel (Steel Washer) 40-45 54-61
Nut-Exhaust Manifold 30-35 41-47
Nut-Connecting Rod 60-70 81-95
Nut-Water Pump Impeller 45-50 61-68
Aluminum Flywheel Housing & Front Cover 10-20 14-27
Nut-Connecting Rod 60-70 81-95
Bolt-Connecting Rod to Pin 55-60 75-81
1/2-13
 Standard Torque Specification 71-75 96-102
Bolt-Flywheel Housing 90-100 122-136
Bolt-Idler Gear Hub and Dummy Hub 80-90 108-122
Bolt-Tach. Drive Cover 35-35 47-47
Bolt-Idler Gear Hub and Dummy Hub (Military 8-V71 T) 105-115 142-156
Bolt-Flywheel Housing Large Hole Cover 30-35 41-47
Bolt-Trunnion TOI Block 105-115 142-156
Bolt-Rocker Shaft Bracket to Cyl Head 90-100 122-136
1/2-20
 Standard Torque Specification 83-93 113-126
Bolt-Blower Rotor Gear Retainer 100-110 136-149
Bolt-Fuel Pump Drive 55-65 75-88
9/16-12 Standard Torque Specification 90-100 122-136
9/16-18
 Standard Torque Specification 107-117 145-159
Bolt-Cam Gear R.B. (300M) Crankshaft 180-190 244-258
Bolt-Flywheel 180-190 244-258
5/8-11
 Standard Torque Specification 137-147 186-199
Bolt-Starter to Aluminum Flywheel Housing 95-105 129-142
Bolt-Main Bearing (Boring) 165-175 224-237
Bolt-Main Bearing (Assembly) 180-190 244-258
Bolt-Cylinder Head 190-200 258-271
5/8-18
 Standard Torque Specification 168-178 228-241
Bolt-Lube Oil Filter Center 50-60 68-81
Bolt-Crankshaft Flange 130-140 176-190
Nut-Alternator Pulley 70-80 95-108
Nut-Special Self Locking, for 10SI Alternator 40-60 54-81
Nut-Cylinder Head 190-200 258-271
3/4-16
 Standard Torque Specification 290-300 393-407
Nut-Accessory Drive Pulley 120-140 163-190
3/4-18 Nut-Standard, Dipstick Tube 30-35 41-47
7/8-14 Standard Torque Specification 475-485 644-658
1-14 Bolt Crankshaft End- 1 5/16 Hex Head 290-310 393-420
1-1/2 Bolt Crankshaft End 440-460 597-624
1 7/16-16 Nut-Blower Drive Gear Hub 50-60 68-81

Detroit Diesel V71 Series Pipe Plug Torque Specifications
Plug Size (in.)
Description
 Torque Specifications
lb-ft N-m
1/8-27 Plug-Pipe (3/4 Taper) 10-12 14-16
1/4-18 Plug-Pipe (3/4 Taper) 14-16 19-22
1/4-18 Plug-Pipe (7/8 Taper) 14-16 19-22
3/8-18 Plug-Pipe (3/4 Taper) 18-22 24-30
3/8-18 Plug-Pipe (7/8 Taper) 18-22 24-30
1/2-14 Plug-Pipe (3/4 Taper) 23-27 31-37
1/2-14 Plug-Pipe (7/8 Taper) 23-27 31-37
3/4-14 Plug-Pipe (3/4 Taper) 33-37 45-50
3/4-14 Plug-Pipe (7/8 Taper) 33-37 45-50
1-11 1/2 Plug-Pipe (3/4 Taper) 75-85 102-115
1-11 1/2 Plug-Pipe (7/8 Taper) 75-85 102-115
1 1/4-11 1/2 Plug-Pipe (3/4 Taper) 95-105 129-142
1 1/2-11 1/2 Plug-Pipe (3/4 Taper) 110-130 149-176
1 1/2-11 1/2 Plug-Pipe (7/8 Taper) 110-130 149-176
1/2-20 Plug-Fuel Pump Relief Valve 18-22 24-30
1 1/4-16 Plug-Oil Filter Bypass valve 95-105 129-142
1 1/2-6 Plug-Oil Filter Bypass valve 110-130 149-176

Detroit Diesel V71 Series Stud Torque Specifications
Thread Size (in.)
Description
 Torque Specifications
lb-ft N-m
7/16-20 Stud-Standard 30-35 41-47
1/2-13 Stud-Aluminum Flywheel Housing W/50DN Alternator 20-25 27-34

 

Additional Detroit Diesel V71 Torque Specs

  1. Standard Pipe Plug Torque Specifications:
    • 1/8″ NPTF: 10-12 lb-ft (14-16 N•m)
    • 1/4″ NPTF: 14-16 lb-ft (19-22 N•m)
    • 3/8″ NPTF: 18-22 lb-ft (24-30 N•m)
    • 1/2″ NPTF: 23-27 lb-ft (31-37 N•m)
    • 3/4″ NPTF: 33-37 lb-ft (45-50 N•m)
    • 1-1/2″ NPTF: 110-130 lb-ft (150-177 N•m)
  2. Cylinder Head Bolts:
    • 5/8-11: 170-180 lb-ft (231-244 N•m)
  3. Main Bearing Bolts:
    • Assembly: 5/8-11; Bolting Torque: 165-175 lb-ft (224-238 N•m)
  4. Flywheel Bolts:
    • 9/16-18: 180-190 lb-ft (244-258 N•m)
  5. Oil Pan Bolts:
    • 5/16″-18: 10-20 lb-ft (14-27 N•m)
    • 3/8″-16: 15-20 lb-ft (20-27 N•m)
  6. Oil Pump Driven Gear Bolt:
    • 60-65 lb-ft (81-85 N•m)
  7. Fuel Pipe Nuts:
    • Endurion-coated: 130 lb-in (14.7 N•m)
    • Uncoated: 160 lb-in (18.3 N•m)
  8. Exhaust Manifold Outlet Flange Nuts (Brass):
    • 3/8-24: 20-25 lb-ft (27-34 N•m)

In the video below the technicians must torque the timing gears to the correct torque specification. After each bolt is torqued it is marked with a paint marker.

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