The Random E46/ZHP Question Thread
Take the belts off. Turn them inside out and squeeze like this:
http://uploads.tapatalk-cdn.com/2016...84b480e466.jpg
If you see any cracks in the ribs. It needs to be replaced
While the belts are off, spin the tensioner and idler pulleys. They should spin relatively easy with no noise or roughness. If they need to be replaced you can replace just the pulleys. No need to replace the tensioners too
Here's a video of a bad pully in my car. You can see it wobble a bit.
https://vimeo.com/182169054