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Old 10-30-2011, 10:37 PM
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bluebee bluebee is offline
Seek to understand,^Value
Location: San Jose, California
Join Date: Mar 2008
Posts: 25,236
Mein Auto: 02 BMW 525i M54 auto 130K
For the record, yet another 540i owner was confused today about the 'ability' to adjust belt tension on the hydraulic tensioners with the arc:
- E39 (1997 - 2003) > Alternator Swap, Loose Belt, Help!

Originally Posted by russelltickle View Post
I put in a new alternator today and need help getting the serpentine belt tight. The Bentley says "turn hex clockwise" to pretension the belt, then tighten the idler arm bolts. I don't know what that means. The tensioner pulleys have a 45 torx bolt if that helps. I also have a tensioner pulley to the lower right of the alternator that doesn't show up in the Bentley or any DIY's I've seen.
How do I get the belt tight on an '02 540? It's on, but squeals at me. I also broke a fan blade, broke a pop pin on the fan shroud, and caused an oil leak by the oil filter housing. But the alternator works!
Here are the links I referred him to for details:
- How to tell if you have mechanical or hydraulic belt tensioners (1) & how to switch from mechanical to hydraulic (1) and what is the difference between the two types (1) (2) & how to rebuild your hydraulic tensioners (1) & the answer to the question of adjusting the 540i hydraulic tensioners' belt tension (1) (2)
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