How to Change the Serpentine Belt on a 6.7 Cummins
January 30, 2024

How To Change The Serpentine Belt On A 6.7 Cummins

Written By: ProSource Diesel

What is a Serpentine Belt?

If you look at the parts on your 6.7 Cummins, the serpentine belt stands out as one of the most essential. The serpentine belt is named for its snake-like appearance, and like a snake, it coils around several engine components, binding them. In addition to connecting several pulleys, it provides power to many crucial systems, including your power steering, water pump, air conditioning, and alternator.

All of the following parts rely on your 6.7 serpentine belt:

  1. Idler pulley
  2. Accessory belt drive
  3. Power steering pulley
  4. Radiator fan pulley
  5. Crankshaft pulley
  6. Air conditioning compressor
  7. Accessory drive belt tensioner
  8. Alternator/Generator
  9. Cummins 6.7 water pump

Look at the diagram below for an idea of how all these pulleys connect to your belt.

How to Change the Serpentine Belt on a 6.7 Cummins

Serpentine Belt on a 6.7 Cummins

Problems With The Serpentine Belt

Every generation of Cummins engine improves upon the last. The serpentine belt is no exception, and the serpentine belt in newer Cummins engines performs better and last longer than its predecessors. Even with improvements, this belt is not immune to failure.

The belt uses a pliable material that allows it to operate at high RPM, putting it under intense stress. Even the most reliable belts will eventually wear down.

The most obvious sign of a worn serpentine belt is squealing or chirping noises. These noises indicate the belt is starting to slip. Slippage comes from low belt tension, a stretched-out belt, or the pulley and belt not working together.

Signs of belt wear are not always obvious, so regularly inspect your belt for damage. Check for cracks, missing pieces, damaged ribs, or uneven wear. Any of these signs means your belt needs replacing.

You can find your Cummins 6.7L serpentine belt below (opens in a new window).

Component Failure

The serpentine belt supplies power to several different systems inside your truck. Your A/C system is one of them. If you’re experiencing technical problems, it might be an issue with your serpentine belt and not an issue with a system-specific component.

A faulty belt is all it takes to make valuable systems underperform. A damaged serpentine belt commonly causes failures in power steering and air conditioning. If you notice a lack of power steering or reduced output from your AC, check your belt before you check anything else.

Complete Breakdown

A worn belt can cause systems to underperform but if your serpentine belt breaks, then your truck becomes undrivable. Several of the components in the above diagram will stop working. If your serpentine belt breaks while driving, call roadside service or replace the belt yourself if you a have spare and the right tools.

A malfunctioning serpentine belt might cause your check engine light to come on. If you have a tuner, you might receive a DTC (Diagnostic Trouble Codes) error.

When To Replace Your Serpentine Belt

A worn or damaged belt will eventually need replacement, even if your truck is working and you don’t notice any noise. It’s easier and safer to stay ahead of repairs and replace your serpentine belt before it breaks. Because the serpentine belt is connected to many important parts, replacing it helps prevent damage to these systems.

You should regularly replace your belt tensioner alongside your belt. An underperforming belt tensioner can cause belt damage.

How Long Does A Serpentine Belt Last?

Current serpentine belts can last between 50,000 and 100,000 miles. Once you hit 50,000 miles, check your belt every 10,000 miles for excessive wear. This applies to your belt tensioner as well.

Replacing The Serpentine Belt

Replacing your serpentine belt can be difficult the first time. The first step is to pop your hood and locate the belt. The belt wraps around several different components, making it easy to spot. Release the belt tensioner from your A/C pulley, then remove the airbox.

You can release the tensioner by undoing one of the bolts. Rotate it clockwise and then move it out of the way. Once this is done, you’re able to remove the old belt.

The diagram below shows how to move the new belt over each pulley. Save the drive belt tensioner for last. You must install the belt in a specific order, so carefully follow the diagram to get it right the first time.

How to Change the Serpentine Belt on a 6.7 Cummins

Serpentine Belt on a 6.7 Cummins

After you’ve guided the belt over all the pulleys, slip it over the tensioner. You can then rotate the tensioner counterclockwise back into place. Redo the bolt. Once you replace the airbox, you’re all done.

Once you’ve gotten the hang of it, replacing a belt is easy. You can have the whole operation done in 30 minutes. Want to make the job easier? Ensure you have all the necessary tools before starting. Having a clean engine also makes the process smoother. Remember to remove the battery negative and never work on a hot engine.


As always, you can rely on ProSource Diesel for replacement Dodge Cummins parts, including 12-valve Cummins parts and 5.9 Cummins parts. If you drive your truck daily, use it for work or for off-roading, we recommend having a spare serpentine belt on hand.

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