Cracked pulleys on a 540i

My BIL has a 2001 BMW 540i wagon. The alternator went on it and in the process of changing it he's discovered that several of the pulleys are cracked. He sent me a picture of one and it basically fell apart when he pulled the serpentine belt off. He's asking me for my opinion on what's going on but I'm a bit stumped. They live a couple of hours away so I can't just nip over and take a look. I've done a quick Google search but nothing seems to jump out. I've taken a good look at the car, in the past, and there's no sign of a front end impact. My only thought is the engine has been changed and the replacement came from a wreck.

I'm hoping that someone else may have a better idea or have experience with this issue.

If it is the plastic pulleys, then it may be an age issue or the belts had too much tension.

Mrs. Zero's 740i had the same issue when I changed the belts and tensioner shocks.

Get all new pulleys and watch the tension. I set all my M60 cars at ~1/2" belt deflection.

The plastic pulleys will disintegrate. The sell aluminium ones at ecs tuning. That is the route that I went on my X5.

Chris

In reply to cdowd:

An X5 manual? That has to be even more scarce than my 525iT manual.

In reply to motomoron: There arn't very many of them. I was very happy when i found it. It came from Florida and had never seen winter.

Thanks for noticing.

Chris