How to change your car engine belt

Changing an engine belt, often referred to as a serpentine belt or accessory drive belt, is a crucial maintenance task for many vehicles.

The serpentine belt drives several key components, such as the alternator, power steering pump, water pump, and air conditioning compressor.

When the belt becomes worn or damaged, it can affect the performance of these systems, possibly leading to failure and costly repairs.

Replacing the belt in time is a relatively straightforward task if done properly.

Below is a comprehensive guide on how to change an engine belt, including tools needed, preparation steps, the belt removal and installation process, and some additional tips to ensure success.

1. Tools and Materials Needed

Before starting, it is essential to gather all the necessary tools and materials. These typically include:

• New serpentine belt: Make sure to consult your vehicle’s manual or a parts supplier to get the correct belt for your make and model.
• Socket set or wrench set: These are needed to loosen the belt tensioner.
• Belt tensioner tool or a long-handled ratchet: This is used to relieve tension on the belt.
• Screwdriver (flathead): In some vehicles, you may need to remove engine covers or other components before accessing the belt.
• Jack and jack stands (if necessary): For some vehicles, you may need to lift the front of the car to access the belt from underneath.
• Work gloves: Protect your hands from sharp components and keep them clean.
• Rag or towel: Use these to clean off dirt or grease from the pulleys.
• Torque wrench (optional): For some vehicles, it may be necessary to use a torque wrench to correctly tighten any bolts related to the tensioner or other accessories.

Step-by-Step Guide to Changing an Engine Belt

1. Preparation and Safety

• Park on a level surface: Make sure the car is parked on a flat surface, with the parking brake engaged. If necessary, use wheel chocks to prevent the vehicle from rolling.
• Turn off the engine: Ensure the engine is off and has cooled down. Working on a hot engine can cause burns or other injuries.
• Disconnect the battery: Disconnect the negative battery cable to prevent any electrical accidents, especially if your car has electronic tensioners or sensors near the belt area.

2. Locate the Serpentine Belt

• Consult your manual: Refer to the vehicle’s manual to locate the serpentine belt. In most cars, it is located at the front of the engine, but in some transverse-mounted engines, it may be on the side.
• Inspect belt routing: Most vehicles will have a belt routing diagram either on the fan shroud, near the radiator, or in the owner’s manual. If no diagram is available, take a clear picture or draw a sketch of how the belt is routed around the pulleys. This is essential when installing the new belt.

3. Inspect the Belt and Pulley System

• Check for wear and damage: Before removing the old belt, inspect it for signs of wear, cracks, fraying, or glazing. Look for excessive wear on the pulley grooves. If any pulleys or tensioners seem worn or damaged, they may need replacement as well.

4. Relieve Tension on the Belt

• Locate the tensioner: The serpentine belt is kept tight by an automatic belt tensioner. This tensioner is usually a spring-loaded arm with a pulley that presses against the belt.
• Use a tensioner tool or ratchet: Insert a wrench, ratchet, or belt tensioner tool into the tensioner’s square drive hole or bolt. Rotate it to relieve tension on the belt. The direction will depend on the vehicle, but generally, you’ll push or pull the wrench/ratchet to move the tensioner arm away from the belt.
• Hold the tensioner: While keeping the tensioner in place, slip the belt off one of the pulleys (usually the easiest one to access). Slowly release the tensioner once the belt is free.

5. Remove the Old Belt

• Remove the belt: With the tension relieved, carefully remove the belt from all pulleys. Note the path the belt follows and any obstructions that might have to be moved (like covers or hoses).
• Check the pulleys: While the belt is off, inspect all the pulleys for smooth operation. Spin each pulley by hand; they should rotate smoothly without wobbling or noise. If any pulley feels rough or makes noise, it may need to be replaced.

6. Compare the Old and New Belt

• Ensure correct belt: Place the new belt next to the old one and compare their lengths and widths. The new belt may be slightly shorter due to the old one being stretched over time, but they should be close in size. If the new belt is significantly different, double-check the part number.

7. Install the New Belt

• Follow the diagram: Use the routing diagram you noted earlier or refer to the vehicle’s manual. Begin by wrapping the new belt around the bottom-most pulley (often the crankshaft pulley), working your way up to the easier-to-access pulleys.
• Keep it aligned: Ensure the belt is seated properly in the grooves of each pulley as you go. A misaligned belt can cause damage to the belt and the pulleys.
• Handle the tensioner: When you reach the final pulley (often the tensioner pulley), use the wrench/ratchet again to move the tensioner. Slide the belt onto the final pulley and slowly release the tensioner, allowing it to apply pressure to the belt.

8. Double-Check Your Work

• Verify alignment: Go around and inspect each pulley to ensure the belt is seated properly in all the grooves.
• Test the tensioner: Check that the tensioner is functioning correctly and applying the right amount of tension to the belt.

9. Reconnect the Battery and Test the Engine

• Reconnect the battery: Attach the negative terminal of the battery back to its post.
• Start the engine: Start the car and let it idle. Watch the belt and pulleys to ensure the belt is running smoothly without slipping or making noise. If you hear squealing or notice abnormal movement, turn off the engine and recheck the belt’s routing and tension.

10. Finishing Up

• Check for noises: Once the engine is running smoothly, check for any unusual sounds such as squealing or grinding, which could indicate a misaligned belt or a failing pulley.
• Replace covers: If you had to remove any engine covers or components to access the belt, reinstall them securely.

Additional Tips

Timing belt caution

If your vehicle also uses a timing belt, make sure not to confuse the serpentine belt with it.

Replacing a timing belt is a much more complicated process and requires precision timing that often involves removing the engine cover.

Frequent inspection

It’s a good practice to regularly inspect your serpentine belt for wear during routine maintenance tasks like oil changes.

Consider replacing the tensioner

If your vehicle has high mileage, consider replacing the belt tensioner along with the serpentine belt.

Tensioners can weaken over time, leading to improper belt tension, which can cause premature belt wear.

Listen for noise

After replacement, keep an ear out for any new sounds from the engine bay. Any unusual noises could signal issues with the belt’s alignment or other components that should be inspected.

By following these steps and taking your time, you should be able to successfully replace a serpentine belt on most vehicles. Always consult your vehicle’s specific manual for any variations or special instructions.