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Your Guide to Serpentine Belt Replacement

Shashank Nakate
The serpentine belt is an advancement over the 'V'-belt that was used for a long time in the car engines. The procedure of replacing a serpentine belt is illustrated through this write-up.
The process of replacing serpentine belt is quite easy, provided that the necessary precautions and steps are undertaken by the installer. A damaged serpentine belt produces noise which indicates whether any repairing or replacement is needed. In order to understand how to replace a serpentine belt, it is first necessary to know about replacement belt.

What is a Serpentine Belt?

It is a belt used in automotive engines for driving the peripheral devices like power steering pump, alternator, A/C compressor, water pump, air pump, etc. Proper working of different parts of a is therefore, dependent on the smooth running of serpentine belt.
This belt is also referred to as a poly-v or multi-vee. A belt tensioner, idler pulley or both are required to guide the movement of belt. Mr. Jim Vance invented the system that makes use of a single serpentine belt instead of number of belts. The Ford Motor company used this belt for the first time for the 'Mustang' in 1979.
A serpentine belt can bear tension and therefore, possesses high mechanical efficiency in comparison to the 'V'-belt. Another benefit of using the serpentine belt is that it needs lesser space to fit inside the engine compartment in comparison to the multiple belt system.

Replacing Serpentine Belt

The serpentine belt should be replaced after the vehicle has covered a distance of 30,000 to 50,000 miles. One should always go with the specifications of the manufacturer. The belt should be inspected in order to carry out any replacement activity.
It must be replaced if it shows any cracks, cuts, deterioration of the edges or turns noisy. The cracks observed along ribs of the serpentine belt indicate that it has reached the stage of replacement. Locating the exact problem apart from that of wear and tear proves to be helpful in the process of replacement or in making the new belt last longer.
Let us now get into the details of serpentine belt replacement through the procedure given further.

Cost of Replacing a Serpentine Belt

The cost of a serpentine belt is $25-$75. The labor charge for replacing this belt is around $30-$120. Thus, it is considered to be useful to learn how to replace a serpentine belt tensioner and the 'S'-belt for saving money. Procedure for the same is given further.


Before you start disengaging the serpentine belt, service manual for that particular automobile should be referred. A belt-routing diagram is provided in such manuals. Try to sketch the routing diagram for your convenience. Although, it may seem a futile activity, sketching the diagram on your own enhances your understanding of the placement of belt.
It is necessary to keep in mind that the belt tensioners are tightly sprung. One should thus, avoid any kind of 'slips', which may cause a serious injury. A specially designed service tool or even a ratchet can be used to relieve the tension. The position at which this tool is mounted should be checked properly.
The tensioner should ideally be resting on the internal 'stop'. The tool may 'jam' if it does not come in contact with the tensioner stop before any other component does. This could also result into the tool slipping off and causing an injury.
The belt can be safely removed after releasing the tension. The process of belt removal should begin from the largest pulley, since it can be accessed easily. One might also have to remove the splash shields before pulling the belt off the assembly.
Once the serpentine belt is removed, these instructions should be followed.

  • Coolant pump should be checked for leakage. Generally, a leakage is responsible for causing noise or bad hearing.
  • The fan clutch should be inspected for fluid leakage or any other damage.
  • The tensioner should also be inspected. There may be a problem of wearing down of the tensioner mechanism or pulley bearing noise.
  • The pulleys should be checked for dust/debris accumulated in the grooves. A wire brush can be used for cleaning.
  • One should check whether any of the hood components make contact with the tensioner, belt or any of the pulleys.

Reinstalling a Serpentine Belt

In the process of reinstallation of serpentine belt, the order which is opposite to that of the belt removal must be followed. All the necessary precautions mentioned for the removal process should be followed. The belt should be routed in an order which is reverse to that of removal.
Care must be taken to see that ribs of the belt are accurately set in the pulley grooves. The tensioner position scale should also be checked. If the arrow in the scale is on the 'tight' side i.e. on other half of the tensioner (between the two lines), the re-installation activity is considered a success.
The serpentine belt, which is also known as the 'S'- belt is a better alternative to the 'V'-belt. The mentioned process of replacing the serpentine belt helps the users in removal and reinstallation. Following the precautions mentioned should help in carrying out the activity in a safe manner.