N57S shredding serpentine belts

ana100 · 12-17-2023, 10:24 AM

M550d pre-LCI, so with N57S. engine. Shred two serpetine belts - it has only one long one.

Changed tensioner and checked all the pulleys, all are OK and working smoothly.

Noticed that the standard belt is a bit too long and it made contact to tensioner "bolt" i.e. the knob which You use to turn the tensioner. Put a shorter belt. Now that shorter belt been running OK for a month, now noticed that there's rubber pieces at the backside of the belt, like it scrubbing somewhere... Can't see where? Harmonic balancer seems fine also. Any ideas?

ana100 · 12-17-2023, 12:23 PM

That's how it looks like. The tensioner vibrates clearly on idle, but not when revs are even slightly higher than idle.

dpalumbo25 · 01-31-2024, 10:06 PM

So I have a 2014 535d. I just did the turbo, tensioners, waterpump, pullys shredded 2 belts. Indy shop changed the harmonic balancer/cam pully. Said this was my source of the belt smoking. ...... now 4 days later i think the timing chain tensions shit the bed. trying to figure this one out..... but Id guess you need a new cam pully. Especially if everything else is moving well.

12-17-2023, 10:24 AM	#1
ana100 New Member 0 Rep 7 Posts Drives: Z4, 530e, M550d, ex...335xi Join Date: Sep 2019 Location: Finland iTrader: (0)	N57S shredding serpentine belts M550d pre-LCI, so with N57S. engine. Shred two serpetine belts - it has only one long one. Changed tensioner and checked all the pulleys, all are OK and working smoothly. Noticed that the standard belt is a bit too long and it made contact to tensioner "bolt" i.e. the knob which You use to turn the tensioner. Put a shorter belt. Now that shorter belt been running OK for a month, now noticed that there's rubber pieces at the backside of the belt, like it scrubbing somewhere... Can't see where? Harmonic balancer seems fine also. Any ideas?
	Appreciate 0 Tweet Quote

12-17-2023, 12:23 PM	#2
ana100 New Member 0 Rep 7 Posts Drives: Z4, 530e, M550d, ex...335xi Join Date: Sep 2019 Location: Finland iTrader: (0)	This is how it looks like That's how it looks like. The tensioner vibrates clearly on idle, but not when revs are even slightly higher than idle. Attached Images
	Appreciate 0 Quote

01-31-2024, 10:06 PM	#3
dpalumbo25 Registered 2 Rep 4 Posts Drives: BMW 535d Join Date: Aug 2023 Location: Pittsburgh PA USA iTrader: (0)	So I have a 2014 535d. I just did the turbo, tensioners, waterpump, pullys shredded 2 belts. Indy shop changed the harmonic balancer/cam pully. Said this was my source of the belt smoking. ...... now 4 days later i think the timing chain tensions shit the bed. trying to figure this one out..... but Id guess you need a new cam pully. Especially if everything else is moving well.
	Appreciate 0 Quote