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      06-25-2019, 01:53 PM   #150
The Kurgan
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Drives: 2012 BMW 328i Luxury Line RWD
Join Date: Jun 2019
Location: Hamilton, Ontario, Canada

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Quote:
Originally Posted by mattwong92 View Post
So update:

Got my car back from the dealership, did not get any work done. They brought in a Engineer Rep from Germany who happened to be visiting the dealership to look at my car (even got him on dash cam lol).

He explained that:
- when the n20 engine cams lobes come to rest vertically straight up at a very specific point the lobe will rotate back slightly (very rarely will it do so it needs to come to a stop exactly at that point).
- When the lobe rotates back slightly on engine stop, there will have slack on the chain that you see in my video (enough to lift the chain 1-2 cm off the guide)
- He said he was very surprised i even noticed this in my car as no one ever looks at it and happens in a very rare use case.
- Otherwise you will see very slight play in the chain, and movement side to side up and down depending on oil pressure due to the hydraulic tensioner used when the lobe takes up all the rest of the slack on the chain.
- Overall listening to my engine he said it sounded very healthy, and the only cases in which the timing chain shows symptoms of going out is the VERY loud high pitched whining noise. Additionally as more and more slack appears in the chain over time you will hear loud noises that sound like rod knock.
- Overall he said a lot of customers are concerned with their timing chains but from every single n20 that has been completely broken down in the shop for the repair they have VERY noticeable sounds and has affected a very low number of cars.
- From the engines and cars that have had this issue they were being driven or had been going over the expected oil change intervals at around 15-20k miles before changing.

Not sure if this info is helpful or not but posting here anyways thanks!
This should be a sticky. It answers the questions about the N20/N26 Timing Chain failure issue, and really puts to rest a lot of anxiety.
Appreciate 0