If your 2013 Nissan Altima has started making a high-pitched squeal or showing signs of battery issues, chances are the serpentine belt needs attention. This single continuous belt powers essential components such as the alternator, water pump, air conditioning compressor, and power steering system. Without it, your engine cannot run smoothly and could overheat or lose electrical power. Many Altima owners struggle to find a clear belt diagram because the routing differs slightly between the 2.5L four-cylinder and the 3.5L V6 engines. This guide provides a complete and accurate serpentine belt diagram with clear explanations and visual references so you can replace or reinstall it with confidence. Whether you are a DIY enthusiast or a professional mechanic, understanding the correct belt routing can save you time, prevent costly mistakes, and extend the life of your engine components. Keep reading to discover how the serpentine belt system works and see the precise diagram for your Altima’s engine configuration.
Understanding the Serpentine Belt System
The serpentine belt in your 2013 Nissan Altima is one of the most important components in the engine bay. It connects the crankshaft pulley to several accessories including the alternator, water pump, air conditioning compressor, and sometimes the power steering pump. As the engine runs, the belt transfers power from the crankshaft to each accessory, keeping them all working in sync. When this belt wears out, cracks, or slips, it can cause squealing noises, loss of electrical charging, or even overheating. That is why understanding how the system works helps you notice early warning signs before serious damage occurs.
In the Altima, the belt system is designed for efficiency and simplicity. A tensioner pulley automatically maintains the correct pressure to keep the belt tight and aligned. There is also an idler pulley that helps guide the belt around the engine’s accessories. This configuration reduces friction and improves performance while minimizing maintenance. Knowing how these parts interact is essential before attempting any replacement or inspection, as incorrect installation could affect the operation of multiple systems at once.
2013 Nissan Altima Belt Diagram (Visual Breakdown)
Before you replace or reinstall the serpentine belt, it is important to understand the exact routing for your specific engine. The 2013 Nissan Altima came with two main engine options, the 2.5-liter four-cylinder and the 3.5-liter V6, and each has a slightly different belt layout. The diagram for the 2.5L engine shows the belt looping around the crankshaft pulley at the bottom, then traveling around the alternator, the water pump, and the air conditioning compressor. It also passes over an idler pulley and through the automatic tensioner, which keeps the belt tight and properly aligned.
For the 3.5L V6 version, the routing path is more complex because the engine includes additional accessories. The belt must weave around multiple pulleys, so using a diagram as a visual guide is essential before removal. Always check that the ribs of the new belt fit perfectly into the grooves of each pulley. A misaligned belt can cause noise or premature wear. You can refer to a labeled OEM diagram or take a clear photo of your current setup before removing the old belt. Having a reference ensures you install the new belt in the correct orientation and direction, avoiding confusion during reassembly.
How to Replace the Serpentine Belt
Replacing the serpentine belt on your 2013 Nissan Altima is a simple process if you follow each step carefully. Before starting, make sure the engine is cool and the car is parked on a flat surface. Gather the necessary tools, including a socket wrench, a belt removal tool or breaker bar, and the new serpentine belt that matches your engine type.
Step 1. Disconnect the battery
Always begin by disconnecting the negative battery cable. This prevents accidental electrical contact while working near the alternator and other components.
Step 2. Locate the tensioner pulley
Find the automatic belt tensioner on the front of the engine. It is a spring-loaded pulley that maintains belt tension. Insert your wrench or breaker bar into the tensioner’s square slot.
Step 3. Release the tension
Rotate the tensioner slowly in the direction that relieves pressure on the belt. Once the belt loosens, carefully slide it off one of the upper pulleys, such as the alternator. Keep the wrench steady and gently return the tensioner to its resting position.
Step 4. Remove the old belt
Take the belt off the remaining pulleys and note the routing pattern. If you did not take a photo earlier, refer to the OEM diagram or this guide to confirm the correct path. Inspect each pulley for dirt, rust, or uneven wear before installing the new belt.
Step 5. Install the new serpentine belt
Position the new belt around each pulley following the correct routing. Make sure the ribs of the belt align perfectly in the grooves of every pulley. Leave the tensioner pulley for last.
Step 6. Apply tension
Use your wrench again to rotate the tensioner and slip the belt over the final pulley. Slowly release the tensioner so it applies pressure and secures the belt. Double-check that the belt is seated evenly on all pulleys and not twisted.
Step 7. Reconnect the battery and test
Reconnect the negative cable to the battery. Start the engine and observe the belt while it runs. It should move smoothly without wobbling or squealing. If you hear noise, turn off the engine and recheck the alignment.
Following these steps ensures your Altima’s serpentine belt is properly installed, helping all engine components operate efficiently and quietly.
Common Mistakes and Troubleshooting
Even a simple serpentine belt replacement can lead to problems if small details are overlooked. One of the most common mistakes is routing the belt incorrectly. If the belt is not placed in the right order around the pulleys, it may slip off or cause the alternator and water pump to stop working. Always double-check the diagram before tightening the tensioner.
Another frequent issue is belt squealing after installation. This usually happens when the belt is slightly misaligned or when the tensioner or idler pulley is worn out. If the noise continues after adjustment, inspect the pulleys for rust, uneven rotation, or looseness. Replacing a faulty tensioner often eliminates the problem.
Sometimes the check engine light or battery warning light appears after a belt change. This may indicate that the alternator is not charging correctly because the belt is not seated properly on its pulley. Shut off the engine and inspect the alignment again.
It is also wise to avoid touching the belt with greasy hands or tools. Oil and dirt can weaken the rubber and shorten its lifespan. Keeping the belt path clean ensures smoother operation and reduces wear. Proper care and careful inspection can prevent most of these issues and keep your 2013 Nissan Altima running quietly and efficiently.
OEM Belt Part Numbers and Replacement Tips
Using the correct OEM serpentine belt for your 2013 Nissan Altima is essential for proper fit and long-term performance. Nissan designed specific belt sizes for each engine type, and choosing the wrong one can cause tension problems or premature wear. For the 2.5L four-cylinder engine, the OEM belt part number is typically 11720-3RC0A, while for the 3.5L V6 engine it is 11720-JA10A. These genuine parts ensure the right length, rib spacing, and material quality recommended by Nissan.
If you prefer aftermarket options, reputable brands such as Gates, Dayco, and Bando produce high-quality belts that meet or exceed OEM specifications. When buying, always confirm that the belt matches your engine model and check the manufacturer’s compatibility chart.
Before installation, inspect the pulleys, tensioner, and idler for smooth rotation. Replacing these components together with the new belt is a smart preventive measure, especially if the car has more than 100,000 miles. Avoid using lubricant or cleaner on the belt since these products can damage the rubber and reduce friction.
A helpful trick is to compare the old and new belts side by side before installing. The new one should have the same width and rib pattern, though it may appear slightly shorter due to tension. Following these replacement tips ensures a quiet, reliable operation and helps your Altima’s accessory system perform at its best.
Conclusion
Understanding the 2013 Nissan Altima belt diagram is one of the simplest yet most effective ways to keep your car running at its best. The serpentine belt powers vital systems such as the alternator, water pump, and air conditioning, which means even a small mistake during installation can affect the entire engine. By studying the correct routing and following each replacement step carefully, you can prevent misalignment, reduce noise, and extend the life of your vehicle’s components.
Whether you use a genuine Nissan belt or a trusted aftermarket option, accuracy and cleanliness during installation make a real difference. Regular inspection every few months can also help you spot cracks, glazing, or fraying before a breakdown happens.
Now that you have the complete serpentine routing guide with images and OEM details, you can replace or check your Altima’s belt with confidence. Bookmark this page for future maintenance and share it with other Altima owners who might need the same reliable reference. Have you replaced your Altima’s serpentine belt recently? Share your experience or tips in the comments below.