How to replace a Micro-V belt in 7 easy steps

The auxiliary belt performs essential functions inside the engine. Once an engine is running, the belt operates continuously. It powers all belt-driven accessories, linking the peripheral belt drive components, which are: tensioners, idlers, torsional vibration dampers and overrunning alternator pulleys. High under-bonnet temperatures plus constant flexing ultimately take their toll. Over time, the belt is subject to wear and will need to be replaced. A properly installed and maintained belt will last longer.

When to change accessory belts

Statistics show that failures increase dramatically after the fourth year of service, so Gates recommends that auxiliary belts be replaced at least every four years or 100,000 km (62,000 miles).

While the four-year replacement interval is a basic rule of thumb, it is not exact. Idling time in traffic, for instance, takes a major toll on belt life. Today’s normal urban driving patterns constitute extreme operating conditions, exposing belts to excessive stress and wear. Therefore, it is imperative to periodically inspect belts – even belts less than four years old – whenever a vehicle comes in for service.

What follows is a general step-by-step procedure for installing auxiliary belts. Note that these are general guidelines. Before attempting to install any belt, always refer to the vehicle manufacturer’s recommended procedures for replacement and maintenance.

How to replace a Micro-V belt


Safety first
Disconnect the car battery and set the hand brake.


Draw a sketch or take a picture of the belt routing.
Before removing the old belt, look under the bonnet and around the engine compartment for the belt routing and make sure you are familiar with the configuration.


Release the tension. You can easily slide the belt off, once the tension is relieved.
Many new cars use an automatic tensioner which makes servicing easy. Release the tension by means of a spanner or socket wrench and block the tensioner in the retracted position.
Other cars use tensioners or accessories which have to be locked down manually to provide the correct tension. These are called locked centre drives. To remove the belt, release the tension.


Inspect the drive system for wear. Make sure the tensioner and the pulleys are in perfect condition. Gates recommends the installation of a belt kit as part of a drive system overhaul.


Before installing the new belt, check the alignment of the pulleys. Misalignment can cause severe belt wear and damage. It can also create noise or cause belts to get pulled into the timing belt drive. The Gates DriveAlign laser alignment tool allows fast identification of the two most common types of misalignment.


Once you have thoroughly checked the entire drive and replaced any worn components, install the new belt according to your sketch, picture, or belt routing diagram. Carefully align the belt ribs with the pulley grooves and check that the belt fits squarely on each pulley. Run your fingers over any pulleys that cannot be visually inspected to confirm the installation is correct. If not properly installed, the belt can ride up on the pulley, or skip grooves, resulting in severe belt damage.


Apply the correct tension. If the drive has an automatic tensioner, slowly release the tensioner and it will automatically apply the right tension. If the car has a manual tensioner, you will need to apply the correct tension yourself. Applying the right tension is easy with the Gates STT-1 sonic tension tester. It ensures easy and accurate tension measurement every time. It is important that you measure the belt installation tension before letting the engine run. So after having mounted the new belt correctly, the STT-1 is used to check whether the tension is OK, too high or too low. If adjustment is necessary, make the adjustment and measure again. When the installation tension is correct, start up the engine and let the drive run for a few minutes to ensure proper functioning of the belt and even distribution of the tension along the belt’s length. Installation tension should not be re-measured or adjusted after the drive test run.

install confidence counterfeit