A bad serpentine belt can leave you stranded with a dead battery, no steering, or an overheating engine. You may think it’s an easy at-home repair, but any mistakes can cause costly damage to multiple vehicle systems.
So, what should you do about a worn serpentine belt?
The best thing to do is call in a pro, such as one from a trusted mobile mechanic service like AutoNation Mobile Service.
To give you an idea of what to expect, we’ll tell you how a mechanic performs a serpentine belt replacement step-by-step. You’ll also learn about the warning signs of a bad belt, how urgent replacement is, the repair costs, and more.
This Article Contains:
- How to Perform a Serpentine Belt Replacement (Step-by-Step)
- Can You DIY a Serpentine Belt Replacement?
- How Much Does a Serpentine Belt Replacement Cost?
- How Often Do You Need to Replace Your Serpentine Belt?
- 10 Signs of a Failing Serpentine Belt
- Can You Drive with a Bad Serpentine Belt?
- What Other Maintenance Should You Do While Changing Your Serpentine Belt?
- What Is the Difference Between a Serpentine Belt and a Timing Belt?
Let’s begin.
How to Perform a Serpentine Belt Replacement (Step-by-Step)
Performing a serpentine belt replacement on your own isn’t impossible if you have the right tools and technical know-how.
However, it can be risky as the serpentine belt is an important component that runs multiple systems. If you want to ensure the job is done right, it’s best to opt for serpentine belt replacement services, where an expert mechanic can do the job for you.
Let’s dig into the details of how a mechanic handles the serpentine belt replacement process:
Step 1: Note the Belt Placement
The belt path a serpentine belt weaves through is unique to each car.
To note down the fan belt placement:
- The mechanic may take a few snapshots, record a video, or sketch how the old belt winds around different pulleys, such as the idler pulley and the belt tensioner.
- If you already have a loose belt that’s out of place, the mechanic can look for the belt routing in the driver’s manual or a diagram in the engine bay.
Step 2: Examine the Tensioner
The tensioner pulley is what maintains the belt tension around the accessory pulleys.
Before removing the worn serpentine belt, the mechanic will check the belt tensioner for excess vibration.
A well-functioning tensioner should have a slight vibration. A properly tensioned belt should also run smoothly around the tensioner with no visible vibration. If the pulley exhibits a jerky vibration, the belt vibrates, or if the tensioner arm moves more than ¼ inch, it’s a symptom of a faulty belt tensioner.
Step 3: Loosen and Unthread the Belt
To remove the car’s serpentine belt, your mechanic needs to loosen the tensioner pulley first.
Here’s how they do it:
- First, as a safety measure, they’ll disconnect the battery’s negative terminal.
- Place the serpentine belt tool into the square-shaped 1/2-inch or 3/8-inch drive opening. If a serpentine belt tool isn’t available, a long-handled ratchet or breaker bar with an assortment of sockets could also work. They can snap a socket on the hex-shaped nut on the pulley itself.
- Slowly rotate the tensioner arm as far as it can go. This will release the belt tension.
- Remove the old belt from any smooth pulley, then release the tensioner and fully extract the old belt.
NOTE: Every vehicle is different. In some cases, they may have to lift the car and remove parts obstructing the belt, such as the wheel or underbody panels. - On an older vehicle, they’ll use a ratcheting socket tool rather than a breaker bar to loosen the tensioner pulley bolt and the adjuster bolt.
Step 4: Check for Belt Damage
After removing the old belt, the mechanic will do a visual inspection for any signs of damage to confirm that you need a belt replacement.
Separated belt grooves or uneven wear (fraying on only one side) can also indicate misalignment of the serpentine belt or pulleys. This tells the mechanic you may need additional repairs to pulleys or other components.
Step 5: Examine Each Pulley
Your car mechanic will use a straightedge tool to ensure that every pulley is aligned correctly.
They’ll spin the idler pulley and the tensioner pulley (automatic belt tensioner) to check that they move freely without any unusual noise.
The mechanic will also ensure that there are no oil leaks, as they can wear out a belt faster. They’ll brush off any debris around each pulley to prevent misalignment, too.
Step 6: Install the New Belt
Here’s how the mechanic will replace the old belt with a new one:
- Route the new belt around the pulley path using a belt replacement tool, referring to a photo, video, or diagram to ensure the new one follows the original belt path. For proper installation, grooved pulleys need to touch the grooved side of the belt, and smooth pulleys need to touch the smooth side.
- Rotate the tensioner arm as they load the belt and wrap it around the crankshaft pulley.
- Finish off the serpentine belt replacement by sliding the belt onto the idler pulley.
- Slowly release the tensioner. On older vehicles, the mechanic must manually reset the tension by turning the tensioner pulley bolt and adjuster bolt. They’ll then check proper tension, ensuring they can only twist the belt 90 degrees.
- Crank up your engine and let it run for a minute to ensure the new serpentine belt functions correctly.
Now that you know how the replacement is done, you may be asking yourself this question:
How tricky is this repair, and is it really worth the money to call a mechanic?
Can You DIY a Serpentine Belt Replacement?
The bottom line is: If you’re interested in DIY car repairs, replacing your serpentine belt yourself is possible but not recommended.
Why?
The chance of getting it wrong puts your car at serious risk.
The serpentine belt plays a vital role in your vehicle’s operation as it drives multiple accessory systems, affecting the following:
- The battery
- The air conditioning
- Engine cooling
- The power steering pump
- And more
These aren’t just nice-to-haves. Improper installation of the belt can lead to poor performance, car failure, or lasting damage in several critical areas of your vehicle. These issues can be very costly down the line.
Additionally, although replacement belts are inexpensive, you may need to purchase special tools, which add to the repair cost.
With that in mind, let’s look into the repair costs if you opt for a professional.
How Much Does a Serpentine Belt Replacement Cost?
Serpentine belts are pretty inexpensive and have a long belt life.
A serpentine belt replacement can cost anywhere from $90 to $250.
Let’s break that down:
- Parts will cost you $15 to $80.
- Labor ranges between $75 and $170, depending on your car model, location, and the job’s complexity (E.g., whether they need to remove or repair other parts).
How Often Do You Need to Replace Your Serpentine Belt?
Under normal conditions, a serpentine belt can last 60,000 to 100,000 miles.
You can opt for a belt replacement as a part of your overall car maintenance. However, if you have serpentine belt issues, like a worn or loose belt, don’t wait. Get it replaced as soon as possible.
CAR CARE TIP: Applying a belt dressing (a specialized spray for rubber belts) can help prolong the life of your serpentine belt.
Wondering if it’s time for a belt replacement?
Here are the red flags to look out for.
10 Signs of a Failing Serpentine Belt
If you notice any of the following symptoms, a bad serpentine belt could be the cause:
- Unusual noises: Squealing, squeaking, chirping, or growling belt noise from under the hood.
- Visible wear and tear: Cracks, fraying, splits, missing ribs, glazing on the sides, or separating layers on the belt.
- Loss of belt tension: Too much slack or vibration on the belt.
- Air conditioning problems: Weak cooling or A/C not working at all.
- Power steering issues: Steering becomes heavy or unresponsive.
- Electrical issues: Battery warning light, check engine light, or sudden battery drain.
- Trouble starting: Belt failure can prevent the alternator from charging the battery.
- Engine overheating: Since the belt drives the water pump, failure can cause high engine temperatures.
- Loss of engine power or stalling: Due to battery issues or overheating.
- Burnt rubber smell: Belt slipping or overheating against pulleys.
When you notice problems like this, you should contact a mechanic promptly to avoid a total belt failure while driving. Let’s explore the severity in more detail.
Can You Drive with a Bad Serpentine Belt?
Driving with a bad serpentine belt isn’t safe. With a faulty serpentine belt, your car may overheat, stall, battle to start, or become difficult to steer.
What’s more, a failing belt can suddenly snap or slip off while you’re driving, which could cause an accident. A snapped or slipped belt can also whip around the engine bay and cause costly damage to other components.
If you notice warning signs, pull over immediately and call roadside assistance.
Better yet, take note of your belt service intervals and have a qualified professional from a mobile mechanic service like AutoNation Mobile Service take care of it proactively — right from your driveway. They’ll be fully equipped to replace your belt and perform any other repairs that may be needed or convenient at the time.
Let’s explore what other maintenance services you can consider while the mechanic is working in the area.
What Other Maintenance Should You Perform While Changing Your Serpentine Belt?
Since the serpentine belt is related to so many other systems, it’s a good idea to have a mechanic thoroughly inspect and perform any necessary repairs to other components at the same time. This will save you money in the long run, avoiding repeat visits to the mechanic.
- Tensioner and idler pulleys: Check for pulley bearing noise, wobble, or resistance on the belt tensioner; replace if worn.
- Water pump: Inspect for leaks, worn pipes, or play in the pulley (many pumps are driven by the serpentine belt).
- Alternator: Listen for bearing noise, check output, and inspect the pulley alignment.
- Power steering pump: Check for fluid leaks and smooth pulley operation.
- A/C compressor: Inspect clutch and pulley condition and verify it engages smoothly.
- Hoses and clamps: Check for damaged radiator, heater, and bypass hoses, which are often in the same area as the serpentine belt.
- Coolant level & condition: Top up or flush engine coolant if due.
- Motor mounts: Replace worn engine mounts as they can throw pulley alignment off and cause belt wear.
- Oil system: Look for leaks from the valve cover gasket or front main seal that could drip onto the belt.
- Battery and electrical connections: Check alternator cables and clean corrosion.
- Spark plugs & ignition components: Replace spark plugs if they’re due, as the service interval (~30–100k miles) is similar to belts.
- Air filter and cabin filter: Check and replace filters, as these are quick, inexpensive repairs that often align with routine belt service intervals.
Now, let’s wrap up by discussing one other vehicle component that’s commonly mixed up with the serpentine belt.
What Is the Difference Between a Serpentine Belt and a Timing Belt?
A serpentine belt is also known as an accessory belt, drive belt, or fan belt. It’s located outside the engine and drives the engine accessories, like steering, air conditioner, etc.
It’s not the same as the timing belt, which is inside the engine of your car. It keeps the crankshaft and the camshaft in sync so that the engine can run smoothly.
Another difference between a timing belt and a serpentine belt is that timing belts have horizontal “teeth” to fit into the cogwheels of the crankshaft. In contrast, the other has V-shaped grooves running vertically along the belt.
Serpentine Belt Maintenance Made Simple with AutoNation Mobile Service
If your car makes an unusual noise or the engine accessories stop working optimally, it could indicate serpentine belt issues. So, instead of towing your car to an auto repair shop, you can call in mobile serpentine belt replacement services from AutoNation Mobile Service.
With AutoNation Mobile Service, you get:
- Convenient online booking for all your auto repair and maintenance services
- Expert technicians who perform vehicle repairs and maintenance using new inventory
- 12-month | 12,000-mile warranty on all repairs
- Competitive and upfront pricing
- Repairs and maintenance using high-quality replacement parts
Contact us today to book your belt replacement service.