Serpentine Belt shredded, Twice.

Hi everyone... I bought a BMW 318ti 2004 model and its been the best car i've ever own. However, last week it decided to shred the serpentine drive belt that runs the power steering, waterpump, alternator and aircon.

I thought nothing of it as i bought the car with quite high milage so i just got a new one from BMW dealer and slapped it on and it ran perfectly for two days until it shredded that new belt as well. Im convinced one of my pulleys is seized or running off centre but i've checked them and they seem fine and i'm happy to take it in to get fixed, i just want to know that my mechanic isn't going to tell me its something that is not.


Any help will be greatly appreciated.

So... we're talking about this belt?

Thats the belt in question. My pulley layout is slightly different but thats the belt.

It looks like something has pushed it threw a paper shredder, its in small pieces.

Explain?

I've sent it to the BMW mechanics and have asked them to replace all the pulleys and put a new belt on it but that was a seriously expensive option that i would have liked to avoid...

Anyway we'll see if it solves the problem.

If something was seized, you'd hear it instantly. More likely, the belt tensioner isn't holding it tight and it gets eaten when it comes loose.

Ok so you think replacing the tensioner and pulleys will do the trick? Im just worried its an underlying issue. I guess this is the joys of motor car ownership. :O

Did everything work well just before that belt was shredded?
Steering? Electrics? Engine not heating up?

Just wondering if alternator or water pump or power steering pump is stressing that belt more than supposed to.

I had a serpentine belt shred and wrap around WP pulley making it look like a weed whacker....it was the WP bearing failed allowing all to wobble. Replaced WP, fluids etc and all is good.

The mechs you took it too should be able to determine whether it is a pulley, tensioner or the WP or Alternator bearing causing the issue.

@Igr122... Everything was absolutely fine it was very unexpected...

@QAfred... My Mechs just told me the alternator bearing has failed and thus causing friction on the belt. A new alternator is fairly expensive and my mechanic told me that a simple test would have saved me all the issue, He said "every 10000 kilometres i should remove the belt and spin all the pulleys and measure the side to side movement using a vernier calliper". oh well, lesson learnt the hard way but learnt none the less.

Moral of the story, don't assume you know enough to self diagnose an issue in a german made car. :P

Originally Posted by DurbanBMW

@Igr122... Everything was absolutely fine it was very unexpected...

@QAfred... My Mechs just told me the alternator bearing has failed and thus causing friction on the belt. A new alternator is fairly expensive and my mechanic told me that a simple test would have saved me all the issue, He said "every 10000 kilometres i should remove the belt and spin all the pulleys and measure the side to side movement using a vernier calliper". oh well, lesson learnt the hard way but learnt none the less.

Moral of the story, don't assume you know enough to self diagnose an issue in a german made car. :P

Don't worry, it's difficult to always know and notice EVERYTHING yourself, but this forum can give some good ideas about what to check.

Originally Posted by DurbanBMW

@Igr122... Everything was absolutely fine it was very unexpected...

@QAfred... My Mechs just told me the alternator bearing has failed and thus causing friction on the belt. A new alternator is fairly expensive and my mechanic told me that a simple test would have saved me all the issue, He said "every 10000 kilometres i should remove the belt and spin all the pulleys and measure the side to side movement using a vernier calliper". oh well, lesson learnt the hard way but learnt none the less.

Moral of the story, don't assume you know enough to self diagnose an issue in a german made car. :P

Most of the learning comes from failing sometimes. Ive done plenty of dumb stuff and paid the price. I definitely know what to do now thanks to the experience and the wealth of knowledge on this site.

Originally Posted by lgr122

Don't worry, it's difficult to always know and notice EVERYTHING yourself, but this forum can give some good ideas about what to check.

Yeah definitely, Well i've got my car back and i drove it to work this morning and all seams good... I got a new alternator, apparently they do tend to die at about the age of 8 years so mine did well.

This forum is an absolute god send and i am glad i found it and joined. Everyone here ROCKS!!!

Pulley replacement is not that expensive if you DIY. And lots can be learned re that from this board.