Mechanics

Serpentine Belt

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How to Replace a Serpentine Belt Video

The drive belt or serpentine belt is an essential component of your vehicle. The primary belt function is to supply power to the steering system, water pump, air pump (if equipped) air conditioner and alternator. The belt is connected to the drive pulley of the engine to supply power. If the belt fails it will almost always render your vehicle inoperable until the drive belt is replaced. Typically most people are able to replace a serpentine belt themselves with basic automotive repair knowledge. When replacing the belt draw a diagram of the belt routing before you start to avoid confusion. If you have removed the drive belt and need the belt routing you can look it up on a belt routing diagram.

Typical Serpintine Belt Configuration
Typical Serpentine Belt Configuration

There are two different types of belts primarily; the first is a serpentine belt which tends to cross the motor several times to operate additional components. There are several names that are used to describe a serpentine belt, including Poly-V, Multi-Rib, and even a Micro-V Belt. However, all of these terms mean the exact same thing and do not change the way the belt is routed, or the type of material the belt is constructed from. A serpentine belt tends to have several V's in the belt that act as better grip for the drive pulley and components of the drive belt system.

Serpentine Multi Rib Belt
Serpentine Belt (cross view)

Problems you can have with a drive belt are that on occasion it can slip off the pulleys or breaks. When a drive belt slips off the pulley system it usually is because the belt tensioner has worn allowing the belt to become misaligned. To correct this problem the belt tensioner must be replaced. Also inspect the drive belt and replace if needed, it can be damaged when the belt derails.

Serpentine Belt Tensioner
Serpentine Belt Tensioner

The tensioner automatically holds the proper tension on the drive belt so there is no need for re-tightening. If the drive belt is loose the tensioner has failed or the wrong size belt is installed. The tensioner should be about half way between its throw to hold proper tension on the belt. On rare occasions an engine can buck or jerk at start up and can suddenly cause a belt to slip out of place. Other problems can occur if the belt itself snaps this can be due to fatigue of the belt. The most common reason for the belt to snap is the age coupled with the natural wear and tear of the belt.

Cracked Serpentine Belt
Cracked Serpentine Belt

Another problem that can occur is the belt can start to fray. While this will not actually cause the drive belt system to stop working it will cause problems as it comes further apart down the road. Remove and replace the belt if this condition is observed.

Maintenance

For regular maintenance lift the hood and do a complete visual inspection of the belt. Be sure there is no fraying, cracking or any chunks missing. If it appears that any of these conditions exist replace the belt with a new belt. Replacing the belt before it fails is always advisable; it will prevent you from breaking down on the roadside. The drive belt is generally a component that requires maintenance. If you notice that you have to continuously change drive belts, you should have all of your pulleys examined for failing bearings and for excess debris lodged inside the pulley groves. This condition will cause the belt to wear out prematurely.

 If further technical assistance is needed, ask our team of certified car repair technicians.

Related Car Repair Information


How to Replace a Serpentine Belt Video

The drive belt or serpentine belt is an essential component of your vehicle. The primary belt function is to supply power to the steering system, water pump, air pump (if equipped) air conditioner and alternator. The belt is connected to the drive pulley of the engine to supply power. If the belt fails it will almost always render your vehicle inoperable until the drive belt is replaced. Typically most people are able to replace a serpentine belt themselves with basic automotive repair knowledge. When replacing the belt draw a diagram of the belt routing before you start to avoid confusion. If you have removed the drive belt and need the belt routing you can look it up on a belt routing diagram.

Typical Serpintine Belt Configuration
Typical Serpentine Belt Configuration

There are two different types of belts primarily; the first is a serpentine belt which tends to cross the motor several times to operate additional components. There are several names that are used to describe a serpentine belt, including Poly-V, Multi-Rib, and even a Micro-V Belt. However, all of these terms mean the exact same thing and do not change the way the belt is routed, or the type of material the belt is constructed from. A serpentine belt tends to have several V's in the belt that act as better grip for the drive pulley and components of the drive belt system.

Serpentine Multi Rib Belt
Serpentine Belt (cross view)

Problems you can have with a drive belt are that on occasion it can slip off the pulleys or breaks. When a drive belt slips off the pulley system it usually is because the belt tensioner has worn allowing the belt to become misaligned. To correct this problem the belt tensioner must be replaced. Also inspect the drive belt and replace if needed, it can be damaged when the belt derails.

Serpentine Belt Tensioner
Serpentine Belt Tensioner

The tensioner automatically holds the proper tension on the drive belt so there is no need for re-tightening. If the drive belt is loose the tenioner has failed or the wrong size belt is installed. The tensioner should be about half way between its throw to hold proper tension on the belt. On rare occasions an engine can buck or jerk at start up and can suddenly cause a belt to slip out of place. Other problems can occur if the belt itself snaps this can be due to fatigue of the belt. The most common reason for the belt to snap is the age coupled with the natural wear and tear of the belt.

Cracked Serpentine Belt
Cracked Serpentine Belt

Another problem that can occur is the belt can start to fray. While this will not actually cause the drive belt system to stop working it will cause problems as it comes further apart down the road. Remove and replace the belt if this condition is observed.

Maintenance

For regular maintenance lift the hood and do a complete visual inspection of the belt. Be sure there is no fraying, cracking or any chunks missing. If it appears that any of these conditions exist replace the belt with a new unit. Replacing the belt before it fails is always advisable; it will prevent you from breaking down on the roadside. The drive belt is generally a component that requires maintenance. If you notice that you have to continuously change drive belts, you should have all of your pulleys examined for excess debris lodged inside the pulley groves. This condition will cause the belt to wear out prematurely.

 If further technical assistance is needed, ask our team of certified car repair technicians.

Related Car Repair Information

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AUTHOR


Written by
Co-Founder and CEO of 2CarPros.com
35 years in the automotive repair field, ASE Master Technician, Advanced Electrical and Mechanical Theory.


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Article first published (Updated 2013-11-23)