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Serpentine Belt Inspection

Identify Belt Wear Easier with Dayco Tool

Most modern vehicles use serpentine belts that are now made with EPDM compounds. But EPDM belts wear differently than the earlier neoprene constructed belts, making it slightly more difficult to detect when one needs to be replaced.

EPDM belts wear out in much the same way  as tire tread, where there is a material loss from the rib surface. A new EPDM belt will have a traditional “V” profile in the grooves between the ribs. A worn EPDM belt, however, will have a groove profile with the appearance of a “U”, because of the material lost from the rib. Once the rib profile is changed, there is less material and therefore less surface area coming into contact with the pulleys. This material loss can cause slippage, which will affect the performance of the accessories and possibly result in an annoying, noisy belt. Be sure to conduct a good front-end drive system inspection and check for signs of belt wear when a vehicle reaches about 60,000 miles.

Dayco Gauge Helps Identify Rib Profile, Rib Depth and Cracks

The Dayco AWEARness gauge was designed to make identifying signs of wear easier for technicians because it measures wear by looking at the belt rib profile and depth and also determines how many cracks are allowed:

1. Analyzing Rib Profile

PLACE the profile indicator in the belt grooves on a newer belt. You shouldn’t see any side or flank clearance. On a worn belt, you’ll notice the ribs bottoming out. A new EPDM belt will have a traditional “V” profile in the grooves between the ribs.

2. Measuring Rib Depth

To measure the rib depth, keep the tool level and place the belt within it. Then check to see where the top of the bar sits. On a new belt, it should be higher than the top of the rib tips. On a worn belt, the bar will be lower than the top of the rib tips.

3. Checking for Belt Cracks

To measure for cracks, just hold the belt up to the window. If you see four or more cracks, the belt needs to be replaced.

To see a step-by-step overview of how to use the Dayco Awearness Gauge, check out our Measuring Belt Wear video.