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Introduction

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The Cummins ISM, ISMe, and QSM11 engines are widely used in heavy-duty trucks, industrial equipment, marine applications, and power generation units. Proper operation and maintenance require a thorough understanding of engine specifications, including torque values, tolerances, and fluid specifications.

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This article provides a comprehensive guide on the key specifications of these engines, covering torque values for critical components, measurement tolerances, and recommended fluids for optimal performance.

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Parts Catalog for ISM Cummins Marine and Industrial Engines

Parts Catalog for QSM11 Cummins Marine and Industrial Engines

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Engine Torque and Tolerances

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Torque specifications ensure proper tightening of fasteners to prevent component damage and premature wear. The following are key torque values for the ISM, ISMe, and QSM11 engines.

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1. Cylinder Block Torque Values

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The cylinder block serves as the foundation of the engine. Properly torquing the components within this section ensures structural integrity and performance.

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Torque Specs for Cummins Engines

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Main Torque Specifications

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• Crankshaft Pulley: 135 ft-lb (183 N·m)
• Cylinder Liner: 60 ft-lb (81 N·m)
• Front Gear Cover: 35 ft-lb (47 N·m)
• Piston and Connecting Rod Assembly: 75 ft-lb (102 N·m)
• Piston Cooling Nozzle: 15 ft-lb (20 N·m)
  

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Tolerances and Clearances for Cylinder Block Components

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• Cylinder bore diameter: 4.921 in – 4.923 in (125 mm – 125.1 mm)
• Piston-to-bore clearance: 0.0015 in – 0.003 in (0.038 mm – 0.076 mm)
• Crankshaft end play: 0.002 in – 0.007 in (0.05 mm – 0.18 mm)
• Rod bearing clearance: 0.0015 in – 0.0035 in (0.038 mm – 0.089 mm)
  

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2. Cylinder Head Torque Values

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The cylinder head plays a crucial role in combustion, compression, and exhaust flow. Proper tightening ensures seal integrity and prevents head gasket failure.

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Torque Specs for Cummins Engines

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Torque Specifications

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• Cylinder Head Bolts (Final Torque): 230 ft-lb (312 N·m)
• Valve Cover Bolts: 25 ft-lb (34 N·m)
• Rocker Shaft Bolts: 50 ft-lb (68 N·m)
  

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Tolerances and Clearances

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• Valve stem-to-guide clearance: 0.001 in – 0.004 in (0.025 mm – 0.10 mm)
• Valve seat width: 0.050 in – 0.100 in (1.27 mm – 2.54 mm)
  

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3. Fuel System Torque Values

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The fuel system delivers the correct fuel mixture for combustion. Incorrect torquing can lead to leaks, pressure loss, and engine misfires.

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Torque Specs for Cummins Engines

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Torque Specifications

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• Injector Hold Down Bolt: 55 ft-lb (75 N·m)
• Fuel Pump Mounting Bolts: 35 ft-lb (47 N·m)
• Fuel Rail Pressure Sensor: 15 ft-lb (20 N·m)
  

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Tolerances and Clearances

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• Fuel injector nozzle protrusion: 0.002 in – 0.005 in (0.05 mm – 0.127 mm)
• Fuel pressure range at idle: 300 psi – 600 psi (2,068 kPa – 4,137 kPa)
• Maximum fuel inlet temperature: 160°F (71°C)
  

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4. Lubrication System Torque Values

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Proper oil pressure and flow prevent friction, overheating, and component failure.

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Torque Specs for Cummins Engines

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Torque Specifications

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• Oil Pump Bolts: 35 ft-lb (47 N·m)
• Oil Cooler Mounting Bolts: 45 ft-lb (61 N·m)
• Oil Filter Housing Bolts: 35 ft-lb (47 N·m)
  

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Tolerances and Clearances

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• Oil pump clearance: 0.002 in – 0.005 in (0.05 mm – 0.127 mm)
• Main oil pressure regulator valve opening: 30 psi – 65 psi (207 kPa – 448 kPa)
  

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Fluid Specifications

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1. Lubricating Oil Specifications

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Proper engine oil ensures longevity, reduced wear, and optimal engine performance.

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Recommended Oil Types

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• API CJ-4, CI-4 Plus, or CK-4 heavy-duty engine oil
• Preferred viscosity:
  • 15W-40 (normal operating conditions)
  • 10W-30 (for cold weather below -10°F or -23°C)
    

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Oil Pressure Requirements

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• Idle Pressure (Minimum): 10 psi (69 kPa)
• Peak Torque Pressure: 30 psi – 65 psi (207 kPa – 448 kPa)
• Maximum Allowable Oil Temperature: 250°F (121°C)
  

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Oil Capacity

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• Standard Oil Pan (Automotive Applications): 9 gallons (34 liters)
• Transit Bus Oil Pan: 9 gallons (34 liters)
• Marine Applications: 10 gallons (38 liters)
  

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2. Coolant Specifications

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Using the correct coolant mixture prevents overheating, corrosion, and scale buildup.

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Recommended Coolants

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• Cummins-approved Extended Life Coolant (ELC)
• 50/50 mix of antifreeze and deionized water
  

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Coolant System Pressure Limits

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• Maximum pressure: 54 psi (372 kPa)
• Maximum allowable operating temperature: 212°F (100°C)
  

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3. Fuel Specifications

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Using high-quality fuel ensures efficient combustion, extended engine life, and reduced emissions.

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Recommended Fuel Types

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• Ultra-Low Sulfur Diesel (ULSD) – 15 ppm sulfur content
• Biodiesel blends up to B20 (must meet ASTM D7467 standard)
  

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Fuel Pressure Requirements

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• Minimum cranking pressure: 25 psi (172 kPa)
• Pressure at 1200 RPM: 120 psi (827 kPa)
• Governed RPM fuel pressure: 150 psi – 180 psi (1034 kPa – 1241 kPa)
  

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Conclusion

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Proper adherence to Cummins ISM, ISMe, and QSM11 engine specifications is essential for long-term performance and reliability.

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By ensuring correct torque values, tolerances, and fluid specifications, technicians and operators can prevent failures, optimize efficiency, and extend engine lifespan.

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Regular maintenance and strict compliance with manufacturer recommendations are key to keeping these engines operating at peak performance.

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Parts Catalog for ISM Cummins Marine and Industrial Engines

Parts Catalog for QSM11 Cummins Marine and Industrial Engines

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