Cummins ISC 8.3 Belt Routing (Serpentine Belt Diagram)

One of the facts of engine life is that belts will stretch and need to be replaced. This is an easy task if all you are doing is replacing the belts on a regular engine. It becomes more difficult when you have to replace a belt on a modern engine with all of its different pulleys.

Taking a photo of your belt system is a good idea if you do not have a diagram. What is even better is to print out the belt diagram we will place in this article a little later. Having a diagram on hand makes sure you get that new belt routed correctly.

To learn more about this situation and see the belt diagram, just continue to read our article. It has the information you want to know about so you can easily replace worn-out belts on your RV or truck. It is not as easy as it once was.

Cummins 8.3 Serpentine Belt Diagram


In this section, we will provide you with two diagrams to make sure you can see the routing in the best possible light. Despite the many pulleys, it is a straight forward routing that should take little time to replicate.

Here are those diagrams:


The second diagram is just to confirm this routing. It is a picture of the full engine but it does not give as clear of view like the one above does. The second diagram is supposed to come from the Cummins manual as stated on the image.


There is talk that you can remove the pulley powering the air conditioner. It is one way to protect that device till you get it repaired. If you do that option, you would have to remeasure the belt length and buy a smaller one.

There is a little work to doing this but it is supposed to protect the AC compressor when it is already damaged, seized, or just not working. You can always put the pulley back when you fix the AC unit.

But do not do this option unless you are a good mechanic. Too many things can go wrong if you are doing this work for the first time.

Cummins ISC 8.3 Belt Routing


Belt routing for this engine is pretty standard. It reaches all the pullies and you should have no problem accessing it when you need to replace the belts or pull them a bit tighter.

This link will get you to a real-time image of the belt routing so you can see a lot easier how the belts are run. If you scroll down from the image, you will see that there is a right way and a wrong way to adjust the belt tensioner.

Then if you scroll down even further, you will see a full front view of the belt system with instructions on what to do when you need to adjust the tension on the belt. A little further down is a picture with the tensioner circled so you can see the 1/2 hole you need to access to tighten or loosen the belts.

This is not hard work to do but you have to make sure you get the right-sized belt or the system may not work for you. There should be a part number for the belt and there are a couple if you scroll down even further at that website.

Just do not get caught up in the discussion as the members there are talking about if they should buy a new belt and store the old one or buy two new belts and store a new one.

Everyone has an opinion on everything and they do not always line up or provide the correct method to use.

Changing The 8.3 Cummins Serpentine Belt


This is part of the discussion at that website we linked to. The changing of the serpentine belt is simple and easy to do. Once you know the routing or have a diagram to follow, it should not take you that long to get the old belt replaced.

What is the biggest issue in that discussion is if you should store the old belt in case of an emergency or buy a second new one for that purpose. Some people think that the latter option will have the new belt wasting away while not in use.

Those that say you should buy two new belts are saying those belts can last a long time if stored correctly. Plus, there is no guarantee that the old belt won’t snap on you 10 miles down the road once you replace the broken new belt with your old emergency one.

Which way you want to go is up to you. The key is to get the new belt on correctly and those diagrams and photos will help you do that.

Where To Find a New Cummins 8.3 Serpentine Belt


Cummins has a long article about using genuine Cummins parts over the competition’s parts. You can read about it at this link and see if their route is the best way to go. They also have a dealer locator to help you find genuine parts near you.

Or you can go to one of the many auto parts stores to get your belts. There are more than enough of them around so it should be easy to find a replacement belt.

With the parts numbers listed on that website, it should be easy to find a compatible belt for your RV or truck.

Some Final Words

Changing the belts on your truck or RV is not as simple as it once was. But that does not mean it is so complicated you can’t do it yourself. Just follow the diagrams and instructions mentioned above and you should do fine.

When a belt breaks or is worn out, you should be able to change it without too much delay to your trip. It just takes a little skill with hand tools.

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