Fan Drive and Belt System | Power Steering Pump Overview

The drive units in Cummins ISM, ISMe, and QSM11 engines play a critical role in ensuring efficient engine cooling and proper vehicle steering functionality. The fan drive and belt system regulates the engine’s cooling process, preventing overheating, while the power steering pump provides the necessary hydraulic pressure to assist steering.

Proper maintenance and inspection of these components are essential to prevent engine failure, overheating, and loss of steering control. Any belt misalignment, tension issues, or pump failures can lead to serious engine damage or drivability concerns.

This guide provides a detailed step-by-step process for inspecting, maintaining, and replacing the fan drive, belt system, and power steering pump in Cummins ISM, ISMe, and QSM11 engines.

For specific torque values, belt tension specifications, and pump servicing intervals, consult an OEM service manual or contact Diesel Pro Power for expert assistance.

Parts Catalog for ISM Cummins Marine and Industrial Engines

Parts Catalog for QSM11 Cummins Marine and Industrial Engines

Fan Drive and Belt System for Cummins ISM, ISMe, and QSM11

The fan drive system regulates airflow through the radiator, maintaining engine temperature and preventing overheating. The belt system drives multiple accessories, including the alternator, power steering pump, and air conditioning compressor.

Key Components of the Fan Drive and Belt System

✔ Fan Drive Assembly – Controls fan speed based on cooling demand.
✔ Serpentine Belt – Transfers engine power to auxiliary components.
✔ Belt Tensioner – Maintains proper belt tension to prevent slippage.
✔ Idler Pulleys – Guide and support the belt to prevent misalignment.
✔ Cooling Fan – Draws air through the radiator to dissipate heat.

How the Fan Drive and Belt System Works

1. The crankshaft drives the serpentine belt – The belt transfers power to the fan drive assembly, alternator, and accessories.
2. The fan drive regulates cooling – The fan engages or disengages based on engine temperature.
3. The belt tensioner keeps proper tension – Ensures the belt remains secure and does not slip or wear prematurely.
4. The fan modulates airflow – Helps cool the radiator and regulate engine operating temperature.
   

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Common Fan Drive and Belt System Issues

A malfunctioning fan drive or belt system can cause engine overheating, excessive belt wear, and accessory failures.

Step 1: Inspecting the Fan Drive and Belt System

1. Check Belt Condition for Wear and Cracks
   

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   • Look for fraying, glazing, or cracking on the belt surface.
   • If wear is significant, replace the belt immediately.
     

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2. Inspect Belt Tension and Alignment
   

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   • The belt should deflect slightly under pressure but remain firm.
   • Use a belt tension gauge to measure tension according to OEM specifications.
     

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3. Check the Fan Drive Clutch Operation
   

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   • Start the engine and let it reach operating temperature.
   • Observe whether the fan engages and disengages properly.
     

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4. Inspect Idler Pulleys and Tensioner
   

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   • Spin each pulley by hand and check for excessive play or grinding noises.
   • If any pulleys wobble or make noise, they should be replaced.
     

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Step 2: Replacing the Serpentine Belt

1. Loosen the Belt Tensioner
   

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   • Use a wrench or belt tensioner tool to release belt tension.
     

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2. Remove the Old Belt
   

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   • Carefully slide the belt off all pulleys while noting the routing pattern.
     

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3. Inspect All Pulleys Before Installation
   

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   • Check for excessive play or signs of bearing wear.
     

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4. Install the New Belt
   

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   • Route the belt according to the engine’s belt diagram.
   • Ensure the belt sits properly in each pulley groove.
     

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5. Adjust Belt Tension
   

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   • Use a tension gauge to set the correct tension level.
     

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6. Start the Engine and Check Belt Operation
   

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   • Observe belt movement and listen for abnormal noises.
     

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Power Steering Pump Overview for Cummins ISM, ISMe, and QSM11

The power steering pump provides hydraulic pressure to assist in steering, reducing the effort needed to turn the wheels. A failing power steering pump can result in stiff steering, fluid leaks, or whining noises.

Key Components of the Power Steering System

✔ Power Steering Pump – Pressurizes hydraulic fluid for steering assistance.
✔ Reservoir Tank – Stores power steering fluid.
✔ Steering Gearbox or Rack and Pinion – Converts hydraulic pressure into mechanical force.
✔ Power Steering Hoses – Transport fluid between components.
✔ Pulley and Drive Belt – Powers the pump from the engine.

How the Power Steering Pump Works

1. The pump draws fluid from the reservoir – The fluid is pressurized inside the pump.
2. Pressurized fluid is sent to the steering gearbox – This assists the driver in turning the wheels.
3. Fluid returns to the reservoir – Excess pressure is relieved and recirculated.
   

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Common Power Steering Pump Issues

Step 1: Inspecting the Power Steering Pump

1. Check Power Steering Fluid Levels
   

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   • Fluid should be between the min/max marks on the reservoir.
   • Low fluid may indicate a leak or excessive wear.
     

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2. Inspect Hoses and Connections for Leaks
   

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   • Look for fluid pooling around hoses or the pump assembly.
   • Replace any cracked or leaking hoses.
     

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3. Check Pump Operation While Steering
   

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   • Turn the wheel at idle and under load to listen for noises.
     

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Step 2: Replacing the Power Steering Pump

1. Drain the Power Steering Fluid
   

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   • Use a fluid extraction pump to remove old fluid from the reservoir.
     

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2. Remove the Drive Belt from the Pump Pulley
   

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   • Loosen the belt tensioner and slide the belt off the pulley.
     

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3. Disconnect the Hoses from the Pump
   

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   • Use a catch pan to collect leaking fluid.
     

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4. Unbolt and Remove the Power Steering Pump
   

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   • Keep track of all mounting hardware for reinstallation.
     

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5. Install the New Power Steering Pump
   

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   • Torque all bolts to manufacturer specifications.
     

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6. Reconnect Hoses and Refill with New Fluid
   

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   • Use OEM-recommended power steering fluid.
     

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7. Bleed the Power Steering System
   

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   • Start the engine and turn the wheel lock-to-lock to remove air.
     

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Final Notes on Drive Units Maintenance for Cummins ISM, ISMe, and QSM11

✔ Check belt tension and pulley alignment regularly.
✔ Replace power steering fluid every 50,000 miles or per OEM recommendations.
✔ Inspect the fan clutch for proper engagement and disengagement.
✔ Monitor steering response and fluid levels to detect early pump failure.
✔ Consult an OEM manual or Diesel Pro Power for precise servicing guidelines.

By following these detailed procedures, you ensure efficient cooling, optimal steering performance, and extended service life for Cummins ISM, ISMe, and QSM11 engines.

Parts Catalog for ISM Cummins Marine and Industrial Engines

Parts Catalog for QSM11 Cummins Marine and Industrial Engines

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