Serpentine belt is not getting tight?

2011 BMW 535I
108,000 MILES • 3.0L • 6 CYL • TURBO • 4WD • AUTOMATIC
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ALBERTNESHA
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I recently changed my alternator with help but once they put the belt on it isn't getting tight, I've been looking for a diagram for my model and can't it's an xdrive 5 series.
Oct 11, 2024 at 10:42 AM
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STRAILER
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So, either the alternator is the wrong pulley size, the belt is the wrong size, or the serpentine belt tensioner needs to be replaced. Here is how the belt should be routed and how to change the belt tensioner out in case you need it, the belt tensioner should work smoothly and have plenty of tension. Check out the images (below). Please upload pictures or videos in your response of any problems so we can see what to help you with.
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Oct 11, 2024 at 11:49 AM
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ALBERTNESHA
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Belt is the same belt that was already on the car right size alternator.
Oct 11, 2024 at 12:43 PM
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STRAILER
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That only leaves the tensioner or the belt routing, can you confirm the routing is correct?
Oct 11, 2024 at 2:35 PM