Video Transcript
Some people call it the serpentine belt, some people call it the accessory drive belt. Either way, it’s something you don’t want to make a mistake about because if the belt breaks down on the road, everything comes to a stop, whether it’s your commute to work or a trip across the country. So let’s look at replacing the serpentine belt right here, right now. Welcome to the AutoZone DIY Garage.
Whenever you’re working under the hood, it’s important to observe basic safety precautions. Always wear proper eye protection, set the parking brake, and be sure automatic transmissions are in park and manual transmissions are neutral to avoid burns. Allow your vehicle to cool before doing any type of repair. Don’t wear loose clothing or jewelry that could get caught in moving parts or might bridge electrical connections. And before you begin work, be sure the vehicle is parked in a level area and that the wheels are chocked to prevent any unintentional movement.
The important thing to keep in mind is that you need to replace the belt before it’s worn out. Once it breaks, you’re not only stuck, but it may seriously damage your engine. A good rule of thumb is if your vehicle has more than 85,000 miles, it’s time to inspect the belt for signs of wear. Checking the condition of the belt is not as easy as it used to be when belts showed signs of wear by cracking or fraying, but you can still look for obvious signs of wear and tear. Modern serpentine belts are made with a new kind of rubber that wears like a tire tread, making wear difficult to see. Today’s belts are wide and have multiple ribs across the surface. A typical belt has five ribs with a V-profile in the grooves between the ribs. Once they get worn though, those grooves begin to look like a U instead of a V. This is what you look for when you’re inspecting a serpentine belt for wear. When you see that U shape instead of a V, you’re seeing material loss from the rib, which means less contact with the pulleys. That typically causes poor accessory performance and noise.
Okay, now that we’ve inspected the belt for signs that it needs replacing, we need to determine which of the two types of serpentine belt drives our vehicle has. There are two types of serpentine belt drives: drives with automatic belt tensioners and manually tensioned drives, also known as locked center drives.
The job of removing the old belt is different for the two different types of belt drives. What we’re showing here is the automatic belt tensioner with an idler pulley mounted on a spring-loaded extension arm to maintain tension. This is used on a large percentage of today’s cars. The tools used to remove a belt from an automatic tensioner drive include a socket wrench and a breaker bar or a specialized belt installation tool. All are available at AutoZone. The most common method for releasing tension off the belt to make it easier to remove is to use a breaker bar with the socket on the end of it attached to the bolt head on the idler pulley. That will give you a firm grip on the idler pulley. Some tensioner designs have a square hole into which the breaker bar is inserted to obtain the necessary leverage. Use the breaker bar to apply torque on the pulley to rotate the tensioner arm, releasing tension on the belt. Then slip the belt off the tensioner pulley, then off an idler pulley like this one, and finally slip it off the rest of the pulleys. Now you’re ready to install the new belt.
Before you start, take a good look at the old belt to make sure that there’s no obvious misalignment. Also, take note of the routing of the belt. Taking a picture is a good idea. Proper alignment is critical. Pulley misalignment results in belt noise, glazing, groove jumping, and ultimately a broken belt. So you always need to do an alignment check before you install the belt. Once you’ve established that everything is properly aligned, spin the tensioner pulley and all the accessory pulleys to verify that they are rotating freely and not damaged. And while the belt is still off, inspect the tensioner for proper movement through its total range. Check for binding, sticking, or total lockup. Any of these conditions mean the need for replacement. If this tensioner is working fine, now you’re ready to install the new belt. Referring to the belt tension diagram or installation guide to make sure it’s going the right way, use the same tool you used earlier and engage the pulley bolt or square hole near the end of the pivot arm. Rotate the tensioner arm and position the belt around the crankshaft pulley. Make sure the belt is tracking correctly in the pulley grooves on the tensioner and all the accessories. When you’re confident of the routing, relax the tensioner arm and remove the tool. Then make a final visual check. That was the procedure for changing a serpentine belt with an automatic tensioner drive. On vehicles with lock center drive adjusters, an adjustment to tension needs to be made to loosen the tension enough that the belt can be removed. That’s the story of replacing your serpentine belt. We hope this information helps when you decide to do the job yourself. It’s always helpful to consult with someone you trust for more details on serpentine belts or other frequently asked questions. Be sure to talk to the experts at AutoZone. Remember, parts are just part of what we do.
