Rick's Free Auto Repair Advice

When to replace a serpentine belt

When should I replace my serpentine belt

Do you know when to replace a serpentine belt? Do you replace it as soon as you see cracks? If so, how many cracks? Well, you’ve come to the right place because I’m going to ‘splain it all to you.

Serpentine belts are made from either Neoprene or ethylene propylene diene terpolymer (EPDM). Nitrile belts generally last about 30,000 to 40,000 miles before cracking to the point where they need replacement. How many cracks before you replace a serpentine belt?

Replace a neoprene serpentine belt when it has three or more cracks in a 3-inch section.

when to replace a serpentine belt, crack in serpentine belt.

This one is toast. It has too many cracks in a a three inch section.

replace serpentine belt

This one must go–too many cracks in a three inch section




Replace a Neoprene serpentine belt when chunks are missing

replace serpentine belt

Replace if any ribs are missing








But EPDM belts are different

EPDM doesn’t crack like neoprene. They last much longer–almost 100K miles. But they’re also much harder to evaluate. You need a wear gauge to measure how deep the ribs have worn. Gates offer a free app for apple and android devices. You boot up the app and snap a picture of the belt ribs. The app measures the wear.

serpentine belt wear app

Click here to see how the Gates serpentine belt wear app works






Check the back side of the serpentine belt

And don’t forget to check the back side of the belt. The back side of a serpentine belt drives the water pump and idler pulleys. It can glaze over, chunk out, fray, or simply wear too thin.

© 2015, Rick Muscoplat

serpentine belt wear

Back side wear

serpentine belt wear

Notice the wear on the backside. This can cause squealing and slipping


©, 2015 Rick Muscoplat



Posted on by Rick Muscoplat

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