N20 Engine High Pitch Squealing

AJLION · 11-10-2023, 11:07 AM

For context, this engine is from a 2014 428i, it has 122k miles, I got no clue if the timing chain was ever replaced but this feels unrelated.

Probables: A/C compressor got replaced last week, this engine has broken a belt a few months ago and I replaced the tensioner when that happened. Additional probable the Altenator in ISTA shows as missing so maybe it’s failing?

I started my car to get it on Rhino Ramps as I was about to do an oil change but hearing this sound for the first time has me pausing that until I figure out what’s going on...

Here are the videos showing both interior and engine bay shots at startup and revving (the sound is intermittent)
Interior Video
Engine Bay Video

Any help will be greatly appreciated thanks.

fe7565 · 11-11-2023, 11:21 AM

To me sounds like belt slipping. But could be metal on metal, or a fan blade. Serpentine belt tensioner installed properly?

Billfitz · 11-11-2023, 12:49 PM

That's either the serpentine belt, belt tensioner, alternator bearing or AC compressor bearing.

11-10-2023, 11:07 AM	#1
AJLION Financially Irresponsible Miami Cinematographer 10 Rep 24 Posts Drives: G12 740i, E92 335is, G42 M240i Join Date: Mar 2020 Location: Ft. Lauderdale, Florida iTrader: (0)	N20 Engine High Pitch Squealing For context, this engine is from a 2014 428i, it has 122k miles, I got no clue if the timing chain was ever replaced but this feels unrelated. Probables: A/C compressor got replaced last week, this engine has broken a belt a few months ago and I replaced the tensioner when that happened. Additional probable the Altenator in ISTA shows as missing so maybe it’s failing? I started my car to get it on Rhino Ramps as I was about to do an oil change but hearing this sound for the first time has me pausing that until I figure out what’s going on... Here are the videos showing both interior and engine bay shots at startup and revving (the sound is intermittent) Interior Video Engine Bay Video Any help will be greatly appreciated thanks.
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11-11-2023, 11:21 AM	#2
fe7565 Lieutenant Colonel 553 Rep 1,581 Posts Drives: 2012 BMW 328i N26 Join Date: Nov 2013 Location: United States iTrader: (0)	To me sounds like belt slipping. But could be metal on metal, or a fan blade. Serpentine belt tensioner installed properly? __________________ Help each other: if you manage to fix your issue (especially with help from this forum), don't be a dck and disappear. Follow-up by posting the solution so you can help others. Last edited by fe7565; 11-11-2023 at 11:39 AM..*
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11-11-2023, 12:49 PM	#3
Billfitz Lieutenant General 8243 Rep 16,082 Posts Drives: '15 328iX GT Join Date: Jan 2015 Location: New Hampshire iTrader: (0)	That's either the serpentine belt, belt tensioner, alternator bearing or AC compressor bearing.
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