Serpentine belt

2011 BMW 535I
120,000 MILES • 3 CYL • AUTOMATIC
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LDARDAR
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I had the tension pulley replaced first. Then a month later the serpentine belt broke. I had that replaced. The alternator was making noise. Now the serpentine belt broke again. I had the the air flow mass sensor replaced also. Now I brought a new alternator and serpentine belt. My question is, will this alternator replacement resolve my belt problem?
Sep 29, 2019 at 9:00 AM
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KASEKENNY
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Hi,

It could however, we need to inspect all the other pulleys and make sure they are not binding, making noise, or misaligned. Basically the pulleys all need to be lined up or it puts pressure on the others and they end up failing or the belt breaks. The other thing that comes to mind is if the belt is too tight.

https://www.2carpros.com/articles/how-a-serpentine-belt-tensioner-works

Before completely the repair and installing the new belt, I would just make sure no other pulleys are causing issues.

Also, did you happen to notice if the belts were melted at all? If one of the pulleys is locked up it will cause excessive heat and break the belt. If they are frayed then most likely something is not aligned properly.
Sep 29, 2019 at 11:13 AM