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Replacing the serpentine belt on 5.9 and 6.7 Cummins engines is a challenging task due to tight spaces, but with step-by-step guidance, it can be done efficiently. Follow the instructions below to ensure a successful replacement.

Preparing for the Replacement

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Begin by removing the air filter and airbox all the way back to the turbo. This will provide more room to access the belt and pulleys. Since setups may vary by vehicle, adjust accordingly based on your specific configuration.

Next, use a 13mm ratchet to loosen the nut holding the fan shroud on the bracket. Wedge a deep well socket between the bracket and the fan shroud to hold it back. Repeat the same step for the bottom passenger side to create additional space for your hands and tools.

For durability and reliability, consider using a high-quality replacement like the 5.9 Cummins serpentine belt.

Removing the Old Belt

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Use a fan belt tool to slide into the tensioner and push it toward the driver’s side. This will relieve tension on the belt and allow you to remove it. Carefully work the belt out from around the pulleys.

Removing the belt from between the crankshaft and the fan pulley can be particularly challenging. Lay underneath the truck to push the belt out, and then pull it the rest of the way from the top.

Installing the New Belt

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Start by sliding the new belt down the passenger side of the engine. From underneath the truck, route the belt around the crankshaft. This process requires careful effort, as the fit can be very tight in this area.

Component

Routing Instructions

Crankshaft

Wrap the belt around the crankshaft and fan pulley.

Power Steering Pump

Route the belt around the power steering pump and push it back up around the bottom of the crankshaft.

Water Pump

Slide the belt between the water pump and crankshaft.

Securing the Belt

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Hold the belt in place and slide the tensioner into position. Ensure the smooth side of the belt is against the appropriate pulleys. Using a torque wrench and a 13mm socket, tighten the tensioner bolt to 32 ft-lb.

Next, route the belt around the air conditioner compressor and alternator. Use the fan belt tool to adjust the belt as needed. Verify that the belt is properly seated on all pulleys and aligned with the grooves.

Final Steps

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Reinstall the air filter and airbox. Secure the fan shroud back in place by tightening the bolts. Start the engine and observe the belt operation to ensure everything is functioning correctly.

For expert advice or additional assistance, consult a trusted Cummins engine dealer, where you can also source genuine replacement parts.