Last Updated: 07.04.2022

The 6.7 diesel engine has numerous components that work together for the engine to function. While some parts are powered directly by the battery, others use the serpentine belt. For example, while an AC compressor does a particular function in the truck, it won’t work without a serpentine belt.

A serpentine belt maneuvers through several pulleys at high velocity each time you start the car. But over time, these belts can break or start showing signs of wear and tear, and at that point, they need to be replaced. That’s why it’s a great thing for truck owners to know how to change serpentine belt on 6.7 Cummins. All things considered, it is a simple task, and doing it yourself can save you time and money.

But first… 

What Is a Serpentine Belt?

car engine with serpentine belt

The serpentine belt is a belt that is connected to a couple of pulleys and also powers some crucial systems in the truck. Serpentine belts get their name from the serpentine shape they create when stretching over accessory pulleys. 

Some of the systems powered by the serpentine belt include the alternator, air conditioner, and power steering.

The belt is also guided by belt tensioners or/and idler pulleys. For the belt to stretch over three pulleys with a considerable wrapping angle, the idler pulley must be pressed against its back. These idler pulleys give the belt its serpentine appearance. The serpentine belt has some grips that ensure that it won’t slip when spinning around the pulleys.

How Long Does a Serpentine Belt Last?

serpentine belt of 6.7 cummins

Generally, a serpentine belt can serve the engine up to 50,000 miles to 100,000 miles. Therefore, you should start monitoring it for wear and tear after every 10,000 miles. And while you’re examining the belt, make sure you look at the tensioners.

When and Why Should I Change the Serpentine Belt?

Contrary to popular belief, most of the engine components aren’t powered by the truck’s battery. Instead, they are powered by the crankshaft’s spinning motion. 

The serpentine belt transfers the crankshaft’s spinning motion from one pulley to the next. So if you have a supercharged truck, then the supercharger is powered by the serpentine belt.

As mentioned earlier, this belt tends to wear out after spinning for certain miles. That’s because the material used to make the belt is vulnerable and can easily crack when rotating at high speed. 

What you need to remember is that driving with a damaged belt can be very dangerous. So it’s crucial that you replace it when damaged. 

Some of the signs of damaged serpentine belts include:

Crack and Wear

cracked timing belt of 6.7 cummins

Generally, the only way to confirm if the belt has cracked is by monitoring it regularly. So make sure you examine the belt every 10,000 miles. If the ridges are uneven, cracked, or missing, you need a new serpentine belt.

Chirping Noises

When some of the ridges on the belt wear out, the belt will start slipping. This will result in the engine producing some chirping noises when the truck is turned on. The slippage is caused by low belt tensions, overstretched belts, or the accessory pulleys and belts not functioning.

Air Conditioning and Power Steering Failure

The serpentine belt normally powers the air conditioner and power steering. So when the belt is damaged, it won’t transfer the spinning power to these accessories. Therefore, when these accessories stop working, then the problem may be the serpentine belt.

Full Breakdown of the Truck

When the serpentine belt breaks, most of the components won’t work, making it hard for you to drive the truck safely. So when it breaks, you should stop the vehicle and call a mechanic or replace it with a new one, if you have one. Generally, when it breaks, the engine check light of most vehicles will turn on.

And if your truck has an onboarding diagnostic system, you will receive an alert when the components malfunction. Thus, if the belt cracks or breaks, you will be alerted by this system. So make sure you examine and change the belt as soon as you receive that alert.

How to Change Serpentine Belt 6.7 Cummins

If you notice any of the signs of a damaged serpentine belt, then it’s time to change it. Before you pop the hood of the truck, you need to get the right replacement belt and tools for the job. But if your truck’s serpentine belt is underperforming, then the issue may be the tensioners. Therefore, you should call a professional to help you out; after all, the belt can be damaged by spoiled tensioners.

For beginners, replacing the serpentine belt can be very frustrating, but it’s not impossible. So the first thing you should do is find out how the belt works and which pulleys it powers. This means locating every pulley connected to the belt and finding out its exact function.

Before you start working on the truck, you should unplug its battery and clean the engine. But most importantly, don’t work on a hot engine. 

To change a damaged serpentine belt, you should do the following steps:

Step 1: Locate the Serpentine Belt

To access the belt, the first thing you must do is open the truck’s hood and look for it. Luckily, locating it can be straightforward—it is the huge belt that goes around more than seven belts and tensioners. For some vehicles, you may have to uninstall the radiator fan and airbox to access the belt.

Fortunately, most professionals can replace the belt without uninstalling the radiator fan. But if you’re doing it for the first time, you should first remove the radiator fan. Once you gain access to the belt, you must release the air conditioning tensioner.

Step 2: Remove the Truck’s Radiator Fan

To gain full access to the belt, you must first remove the radiator fan. So the first thing you should do is unscrew the truck’s airbox and then remove it. Next, remove the radiator fan by loosening the nut connecting the fan pulley to the fan using a 36mm wrench and pulley holders.

Step 3: Release the Engine’s Tensioner

After removing the radiator fan, you can see the belt and all the accessory pulleys it powers. Examine the belt and the pulleys it is powering. Then, draw a simple diagram showing exactly how the belt stretches over the different pulleys and tensioner. 

The diagram will make the installation process easier. Remember, the belt is normally tight, so you should release the tensioner and loosen it.

To access the tensioner’s belt, you need a specialized tool designed specifically for that purpose, like the gear wrench belt remover. With this tool, you can access the bolt and push it downwards to loosen the belt.

Step 4: Remove the Old Serpentine Belt and Install a New Belt

With the belt loosened, you can remove the serpentine belt and examine it for signs of wear and cracks. If the belt is damaged, you should look for a replacement and make sure you get the right option for your truck. 

Now, install the new belt using your diagram as a guide.

When installing the belt, begin with the idler pulley and always finish with the tensioner. Once you have stretched it over all the pulleys and tensioner, you can rotate the nut holding the tensioner in place and tighten it. 

Make sure the belt is installed correctly by comparing it with your diagram. If everything is ok, you can install the airbox and radiator fan. 

Finally, you can start the engine and confirm if all the accessories are functioning.

Next, you should also check out the most common 6.7 Cummins problems

Final Thoughts

The serpentine belt is a crucial part of your vehicle that helps power numerous components. This belt transfers the crankshaft’s spinning motion to different accessory pulleys and powers them. Unfortunately, it can break down with time, so make sure you monitor it after a few miles, and if damaged, it will be great if you know how to change serpentine belt on 6.7 Cummins. Replacing it is considerably easy, though challenging. Just be patient and follow all the detailed steps.