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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Technical Forums > DIY Guides > DIY: Shredded / Broken Serpentine Belt Procedure - E90, E9X 335i N54



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      09-18-2016, 05:03 PM   #1
mr_malvo
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Exclamation DIY: Shredded / Broken Serpentine Belt Procedure - E90, E9X 335i N54

I experienced a shredded serpentine belt a while ago and my experience with it prompted me to write a thread with consolidated information. No doubt there is a lot of information out there regarding belts, broken seals, seized engines etc. However, I felt like it was all scattered and someone like me could have benefited from a once stop thread for all the things that one must check after experiencing a shredded serpentine belt.

My goal with this is to hopefully help someone that goes thru a similar failure scenario and catch the problems before your engine seizes.

Background:
There are several failure scenarios out there that cause a serpentine belt to shred:
- Oil Leaks from Oil Filter Housing Gasket
- Engine mounts allowing power steering pulley to contact sub-frame.
- Faulty belt pulleys/tensioner.

Here is what my belt looked like after it thought I had removed all the pieces from the engine bay.





No matter the cause, once the belt shreds if not handled properly it will be the beginning of bigger problems.

The worst case scenario goes like this:

1. Serpentine belt shreds
2. Pieces of belt wrap around the crankshaft behind the pulley sight unseen
2.a. Owner replaces belt and continues to drive car unaware of belt behind pulley
3. The pieces of belt break past the front crankshaft seal and get tangled in the timing chain.
3.a. This could have happened during the initial belt failure.
4. The timing chain further shews up the belt and pieces fall into the oil pan.
4.a. Big enough pieces of belt can cause your timing chain to skip a tooth.
5. The pieces of belt that fell in the oil pan get sucked in by your oil pick-up.
6. Oil pick-up gets clogged up.
7. Your engine seizes up due to oil starvation.
7.a. If 4.a happens your engine valves can hit pistons due to offset timing.


So how can all this be prevented?

Well, after a shredded belt occurs:

1. REMOVE your front pulley and check for pieces of belt wrapped behind there and also the condition of your front seal.

1.a. If there is none, then you my friend are lucky. Proceed with changing your belt. Here is a Good DIY for That
1.b. If after removing your pulley the seal looks compromised, then you're going to have to do some cleanup. The picture below shows what my seal looked like and the smoking gun piece of belt telling me I had lots to do.




2. A damaged front crankshaft seal probably means pieces of belt made their way into the engine. The amount that did varies from case to case however, please note there's no way of telling how much was ingested until you go in there.


3. Use THIS DIY to REMOVE VALVE COVER.
3.a. With your valve cover removed check for pieces of belt all around the timing chain. The picture below is from my car. I didn't have that much belt clearly visible, however there were pieces wrapped down the pointed areas.



4. Use THIS DIY to REMOVE OIL PAN
4.a. With the oil pan removed check the surrounding areas for belt pieces, but must importantly, your oil pick-up tube. The picture below is what my oil pan and pick-up tube looked like. You can see that is does not take much to start clogging your pick-up tube.



5. With the oil pan removed you will have clear access to the oil pump and the front part of the crankshaft. Look for belt pieces in those areas as well.
5.a. While you're down there inspect the subframe and power steering pulley for damage. My PS pulley was in good condition, and so were the engine mounts.



6. Use THIS DIY to Remove/Replace your front crankshaft seal.



So there you have it. The best advice I can give is to NOT DRIVE YOUR CAR after experiencing a shredded serpentine belt. Check behind that front pulley to avoid yourself future headaches.

I hope this is of help to someone out there. And I'm open to comments/suggestions to expand the information here.
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      09-19-2016, 03:46 AM   #2
DarkNemesis
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Awesome FYI, this should be a sticky.
And thanks for suggesting my Belt and tensioner DIY.

This Thread is extremely well written to address this issue.

Good job Mr. Malvo
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      09-19-2016, 02:01 PM   #3
mr_malvo
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Sure thing, man. Your DIY was also very helpful so quoting it was a no brainier.

Quote:
Originally Posted by DarkNemesis View Post
Awesome FYI, this should be a sticky.
And thanks for suggesting my Belt and tensioner DIY.

This Thread is extremely well written to address this issue.

Good job Mr. Malvo
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