What causes a serpentine belt to break?
Serpentine belt failure — Most common causes
A serpentine belt can fail in several ways:
• A complete break. Usually caused by a seized pulley
• Rib wear that causes the belt to slip and wear. Usually caused by a binding idler roller
• Edge fraying that reduces grip. Usually caused by a component that’s out of alignment with the other components.
• Contamination. Rubber degradation due to oil or coolant leaks and debris accumulation. Use of spray lubricants or “belt dressing”.
Worn/seized bearing in idler roller causes the serpentine belt to break
A worn idler roller bearing causes the roller to bind and drag. That causes belt slipping and wear, along with noise. As the wear progresses, the bearing wobbles, causing the the belt to run out of alignment with the other pulleys in the drive belt system. If an idler bearing or pulley seizes, the belt will slide across the pulley, overheat and break.
Rusted or worn idler face
The rusted surface causes accelerated wear on the belt ribs or backside of the belt, resulting in premature failure.
Leaking gaskets allow oil and coolant to soak into the belt causing rapid rubber degradation. In addition applying spray on belt dressing and lubricating products can degrade the rubber used in serpentine belts.
Belts do NOT need lubrication or belt “dressing.” If a belt is making noise, it’s due to a tension issue or an alignment issue. Fix the underlying problem. NEVER lubricate a belt with a lubricant or belt dressing.
Improper tension can cause a serpentine belt to break
Excessive tension causes the belt to run hot and fail
Low tension causes the belt to slip across the pulleys and wear out the multiple “V’s” to the point where the belt is riding only on its backing.
Improper alignment can cause a serpentine belt to break
The most common cause of belt misalignment is a worn bushing in the automatic belt tensioner. This causes the serpentine belt to run to the side of the pulleys, resulting in edge fraying and rapid wear.
©, 2022 Rick MuscoplatPosted on by Rick Muscoplat