How to Change the Serpentine Belt on a 6.7 Cummins
June 8, 2020

How to Change the Serpentine Belt on a 6.7 Cummins

Written By: ProSource Diesel

What Is a Serpentine Belt?

The serpentine belt is one of the more important 6.7 Cummins parts. The belt name comes from its serpentine appearance as it snakes around several components in the engine. It connects to several pulleys and provides power to crucial systems like power steering, the water pump, air conditioning, and the alternator.

The diagram shows the various pulleys all connected to the belt.

  1. Idler pulley
  2. Accessory belt drive
  3. Power steering pulley
  4. Radiator fan pulley
  5. Crankshaft pulley
  6. Air conditioning compressor pump pulley
  7. Accessory drive belt tensioner
  8. Generator
  9. Water pump
How to Change the Serpentine Belt on a 6.7 Cummins

Serpentine Belt on a 6.7 Cummins

Problems with the Serpentine Belt

Cummins parts have improved in design over the years and the serpentine belt is no exception. New materials have helped create a product that performs better and lasts longer. However, the belt is still constructed of a relatively pliable material that rotates at high RPM every time you drive subjecting it to tremendous wear and tear.

The main symptom of serpentine belt wear is squealing and chirping noises. This happens when the belt starts to slip. Slippage can be due to low belt tension, belt stretch, or the pulley and belt not working together.

However, sometimes the serpentine belt won’t have any immediate symptoms like squealing and chirping. That is why it’s important to visually inspect your belt from time to time. By looking at the belt, you can see if there are cracks, missing parts, damaged ribs, or uneven wear. These are all signs that the belt requires replacement.

Find your Cummins 6.7L serpentine belt below (opens in new window).

Component Failure

In some cases, the failure of components connected to the serpentine belt might be due to belt problems rather than the component itself. The two most common failures related to serpentine belt wear are the power steering and air conditioning systems. If you lose power steering or your AC has reduced output, it’s a good idea to check the belt first. Bad belts can cause these components to underperform or fail.

Complete Breakdown

If your serpentine belt breaks, several components as shown in the earlier diagram will also stop working. This basically renders your truck undrivable. If that happens, you’ll need to either call roadside service or replace it yourself if you have a spare belt handy.

Problems with the serpentine belt can often illuminate the check engine light and, if you use a tuner, you will likely get a DTC (Diagnostic Trouble Codes) error warning about belt problems.

When to Replace Your Serpentine Belt.

If you notice that your belt has damage or wear, but it’s still working and not making noise, should you still replace it? In short, yes. It’s better to regularly replace your serpentine belt when it shows signs of wear or damage rather than let it break when you’re on the road. It’s a safer option, and it also minimizes damage to the other important parts around it.

Along with the belt, it’s also a good idea to replace your belt tensioner regularly. If your belt tensioner is underperforming, there’s a good chance it’s damaging your belt.

How Long Does a Serpentine Belt Last?

With current technology, you can expect your serpentine belt to last between 50,000 and 100,000 miles. After you reach 50,000 miles on the belt, it’s a good idea to check it every 10,000 miles to make sure that it’s not getting overly worn. You can check the tensioner at the same time.

Replacing the Serpentine Belt

The first time replacing this belt can be difficult until you get the hang of it. To start, pop the hood and locate where the belt sits. It should be easy to find as it snakes around several components. Next, release the tensioner from the A/C pulley, then remove the airbox. Undo one bolt and release the tensioner. Rotate it clockwise to move it out of the path. At this point, you can remove the old belt.

Use the diagram to guide the new belt over each pulley. Leave the tensioner for last. It’s important to remember that there’s only one correct way to put the serpentine belt on. In order to get it right the first time, make sure to follow the diagram.

How to Change the Serpentine Belt on a 6.7 Cummins

Serpentine Belt on a 6.7 Cummins


Once you’ve guided the belt over all the pulleys, slip it over the tensioner and then rotate the tensioner counterclockwise back into place. Redo the bolt. Now all that’s left is to replace the airbox.

Replacing the belt isn’t terribly difficult. It requires about 30 minutes of time and focus. Before you start, make sure you have all the necessary tools. It’s also easier to do with a clean engine. Remove the battery negative and don’t work on a hot engine.


As always, 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 or do a lot of work with it, it’s always a good idea to have a spare serpentine belt on hand in case it fails.

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