Serpentine Belt

Serpentine belts are used to drive multiple components at once, making it vital that they stay in decent shape. The same guidelines apply for serpentine belts as for timing and v-belts, though proper storage may be even more important in that if your serpentine belt fails, multiple driven components will be affected.

Shelf Life

The shelf life for serpentine belts is usually seven years when stored in the right conditions. Improper storage could diminish their shelf life, causing them to be inadequate for the intense conditions present in most industrial environments.


Keep serpentine belts in a cool, dry environment away from moisture and in relative humidity below 70%. When it comes to MRO storage, a good rule of thumb is if you are uncomfortable, then your parts are uncomfortable. If you feel like it’s too hot, cold, humid, etc., then you likely need to make some adjustments to maximize the shelf life of your belts.


The maximum temperature for serpentine belts is 85°F (30°C). Exceeding this temperature will reduce shelf life. The same guidelines apply for serpentine belts as for other types of belts where temperature is concerned.


Direct sunlight can reduce the life of serpentine, so it’s best to keep them away from windows. Interior lighting is typically fine as long as they’re not stored too close to lamps.


Ozone can reduce the life of serpentine belts. Common sources of ozone in industrial environments are electric motors, refrigeration systems, and transformers, so it’s best to keep them well away from these devices.


Airborne chemicals can be harmful to serpentine belts, potentially causing premature failure.


Serpentine belts should be stored flat, not hung on hooks or pegs. Keep them off the floor unless you have a dedicated container to protect them from foot traffic and moisture.

How to Read the Date Codes on Belts

Belts come with various markings, including a date code. Often, this code is four numbers. The first two are the week in which it was manufactured, and the last two are the year. For instance:

Example: 0415

A belt marked with 0415 was manufactured in the fourth week of 2015.

Example: 2518

A serpentine belt marked with the digits 2518 was manufactured in the 25th week of 2018.

Example: 4512

A belt marked with 4512 was made in the 45th week (towards the end) of 2012. It’s probably on its way out.

Keep in mind that different original equipment manufacturers may use different marking systems, and it’s especially important to make sure you don’t confuse the date code with the measurement code on the belt. The measurement code will usually have letters mixed in.

Signs Your Belts Are Deteriorating

If a belt has been on your shelf for an extended period of time, it may show some signs of cracking. However, you usually won’t see wear until it has been in use for a while. Signs of belt deterioration include:

  • Cracking in the rubber
  • Delamination (the exterior rubber starts peeling off)
  • Unraveling of internal fibers
  • Twisting
  • Missing cogs or teeth
  • Missed timings and slippage in the machine
  • Buildup of black residue on sheaves and pulleys from belt wear

One of the best ways to keep track of the age of your belts is to keep careful records through your CMMS. With MRO order and inventory tracking, you can more easily determine whether a belt on your shelf is too old to be put into use.

The Dangers of Forced Deterioration of Belts

Belt deterioration due to poor storage or mishandling—also called forced deterioration—can be problematic in many ways. Some of the dangers of forced belt deterioration include the following.

  • Lost production time
  • Inefficient operation of assets as more power goes into running the machine
  • Failure on startup
  • Drive cog slippage and missed timings

It’s rare for belts to completely break while on a machine. Typically, you’ll have wear and tear that decreases the efficiency of the system, driving up the cost of both operations and maintenance. That said, there’s always a safety risk when it comes to working on equipment. If a belt wears out too quickly, it creates more opportunities for injury to those who have to shut down the equipment and replace worn components.

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