Serpentine belt damage AGAIN!

matreyia

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What could be causing this? Razor cut along belt at one section or two??? Inspected this new belt during turbo install and found zero contact points anywhere.

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fmorelli

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You said again. Was last failure identical? I'll be specific - there is no sign of damage to the outside of that belt, so it is not a backside pulley burr that is causing that. That belt is woven. If it is identical = pulley issue. If it is not, looks like a belt failure (defect). That looks like a failing belt - not wear. Good luck and let us know what you figure out.

Filippo
 

matreyia

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Damaged pulley? Try inspecting with the belt off?

Brand new pulley and tensioner last 2 weeks ago replaced.

I theorize that this just happened the day I tested the new turbo and started the engine with the subframe not fully torqued down. Perhaps the belt hit the subframe when I revved the engine...it was pretty loosely bolted.
 

matreyia

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You said again. Was last failure identical? I'll be specific - there is no sign of damage to the outside of that belt, so it is not a backside pulley burr that is causing that. That belt is woven. If it is identical = pulley issue. If it is not, looks like a belt failure (defect). That looks like a failing belt - not wear. Good luck and let us know what you figure out.

Filippo
It may well be defect...that is not an oe BMW Continental belt...that is an oem Continental belt. I will get an actual OE BMW belt tomorrow to replace.
 

doublespaces

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If you've got a bend or wobble in the pulley it could be pushing into the side of it causing it to pancake in from the side.
 

matreyia

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If you've got a bend or wobble in the pulley it could be pushing into the side of it causing it to pancake in from the side.

I watched it over and under car. All is is perfectly aligned. No contact with any part of car or subframe or any ancillary equipment. It may be defect on new belt. Only one section is torn.
 
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Seb335i

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Take a look of your Power steering pump bolt. I had the same issue it was one of the bolt who was unscrewed.
The belt was perfectly aligned with engine off but the pump was wobbling with running engine.
Do you had a serious inspection after the broken serpentine belt ? I can turn in a dramatic issue.
Take a look here https://www.e90post.com/forums/showthread.php?t=1305990
 

matreyia

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Take a look of your Power steering pump bolt. I had the same issue it was one of the bolt who was unscrewed.
The belt was perfectly aligned with engine off but the pump was wobbling with running engine.
Do you had a serious inspection after the broken serpentine belt ? I can turn in a dramatic issue.
Take a look here https://www.e90post.com/forums/showthread.php?t=1305990

I inspected while car was running. Perfect alignment at all angles. No steering bolt issue at all.
 

Asbjorn

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FWIW I replaced my belt and tensioner once, and found unusual wear on one of the new wheels after a short while. Out of fear, I replaced both once more. That was when I discovered the belt was slightly shorter than the original one. Maybe an inch or so. Now Im back to stock length and no issues.
 

matreyia

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FWIW I replaced my belt and tensioner once, and found unusual wear on one of the new wheels after a short while. Out of fear, I replaced both once more. That was when I discovered the belt was slightly shorter than the original one. Maybe an inch or so. Now Im back to stock length and no issues.

WHAT!!!??? Who sold you that shorter belt? Man, I should have stuck with the BMW OE belt. An inch? And it still fit?
 

fmorelli

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On that subject, not all N54 belts are the same, since the Z4 does not run a power steering pump. But that makes our belts shorter, so a "regular" N54 belt would actually be longer.

Filippo
 

matreyia

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Found the reason! Took belt off and inspected power steering pully...it had some teeth missing..chipped and that corresponds exactly to the damage to the belt goegraphically. See pic.
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fmorelli

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Good catch. Looks like it. Curiously what does the inside of the belt look like, where the failure occurred?

Filippo
 

matreyia

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Good catch. Looks like it. Curiously what does the inside of the belt look like, where the failure occurred?

Filippo
The location of the damage site on the inside looks a little "soft and fuzzy" like it's been beaten more than the rest. But not to the point of tearing or anything obvious...you have to look carefully to see there is a slight fuzz.
 

doublespaces

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Considering this pulley is known to make contact with the subframe, I'm not entirely surprised. You did say it wasn't torqued down earlier so maybe that is why. What motor mounts do you have?
 

matreyia

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Makes you wonder how many cars drive around with tons of issues that less OCD people just have no clue exist

I thought the same. So turbos are installed and test drive. With no tune, still feels stronger than stock. However the turbos rattle pretty loud at times... pure says this is to be expected and must be tuned out. Anyone with same experience with pure?