N55 Tensioner Movement (2016 M235i)

USVIJIM · 10-31-2023, 12:30 PM

2016 M235i 65k miles. Changed the tensioner, Idler pulley and belt. Used a new torx bolt and triple checked torque settings. AC off tensioner barely moves, AC on it moves more than I think it should. Getting a slight squeal and can't quite figure where it's coming from. Used a stethoscope and the old screwdriver to the ear.

May need to go to my Euro guy for a diagnostic.

Video with AC on

https://youtu.be/5RhyDvqsPuE?feature=shared

with AC off

https://youtu.be/-_M-kb2pTe0?si=WejHhlGBN9xQoAJg

XutvJet · 10-31-2023, 01:19 PM

Tensioner movement with the AC is completely normal. The AC compressor puts a lot more drag on the accessory drive thus the reason the tensioner moves a bit. Once the tensioner starts moving a lot when the AC is off is when you should be concerned.

I don't hear any weird belt noises. Seems completely normal and sound just like mine.

USVIJIM · 10-31-2023, 01:26 PM

The sound is very minor but wasn't there before. Alternator is good, AC cranks out cold air.

Car runs great otherwise

XutvJet · 10-31-2023, 03:01 PM

Could be that the new idler or tensioner pulley have a bad bearing.

USVIJIM · 10-31-2023, 03:15 PM

The squal was there before. I suspect AC compressor or alternator pulleys. It's not super loud but I know the car well and it sounds different.

10-31-2023, 12:30 PM	#1
USVIJIM Private 14 Rep 52 Posts Drives: 2016 M235i Join Date: Jun 2022 Location: Long Beach, CA iTrader: (0)	N55 Tensioner Movement (2016 M235i) 2016 M235i 65k miles. Changed the tensioner, Idler pulley and belt. Used a new torx bolt and triple checked torque settings. AC off tensioner barely moves, AC on it moves more than I think it should. Getting a slight squeal and can't quite figure where it's coming from. Used a stethoscope and the old screwdriver to the ear. May need to go to my Euro guy for a diagnostic. Video with AC on https://youtu.be/5RhyDvqsPuE?feature=shared with AC off https://youtu.be/-_M-kb2pTe0?si=WejHhlGBN9xQoAJg
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10-31-2023, 01:19 PM	#2
XutvJet Major General 5556 Rep 5,372 Posts Drives: 2011 Cayman Base, 2016 M235 Join Date: Mar 2016 Location: Kansas City iTrader: (-1)	Tensioner movement with the AC is completely normal. The AC compressor puts a lot more drag on the accessory drive thus the reason the tensioner moves a bit. Once the tensioner starts moving a lot when the AC is off is when you should be concerned. I don't hear any weird belt noises. Seems completely normal and sound just like mine. __________________ The forest was shrinking, but the Trees kept voting for the Axe, for the Axe was clever and convinced the Trees that because his handle was made of wood, he was one of them.
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10-31-2023, 01:26 PM	#3
USVIJIM Private 14 Rep 52 Posts Drives: 2016 M235i Join Date: Jun 2022 Location: Long Beach, CA iTrader: (0)	The sound is very minor but wasn't there before. Alternator is good, AC cranks out cold air. Car runs great otherwise
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10-31-2023, 03:01 PM	#4
XutvJet Major General 5556 Rep 5,372 Posts Drives: 2011 Cayman Base, 2016 M235 Join Date: Mar 2016 Location: Kansas City iTrader: (-1)	Could be that the new idler or tensioner pulley have a bad bearing. __________________ The forest was shrinking, but the Trees kept voting for the Axe, for the Axe was clever and convinced the Trees that because his handle was made of wood, he was one of them.
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10-31-2023, 03:15 PM	#5
USVIJIM Private 14 Rep 52 Posts Drives: 2016 M235i Join Date: Jun 2022 Location: Long Beach, CA iTrader: (0)	The squal was there before. I suspect AC compressor or alternator pulleys. It's not super loud but I know the car well and it sounds different.
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