Quote:
Originally Posted by 80stech
Maybe the seal ring gets spun at times like when the oil is thick or even gets stuck to the cam if the car is sitting for a long time and causes the wear especially since the lock portion could have sharp ends. The seal rings can't be holding the cam in place or the teflon ones would never stand up.
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Good call on both points. I looked at a tear down video but not enough detail to see where the axial thrust is held.
On closer look, thrust looks like it's held in place from the inside between the two recangring seals.
https://youtu.be/Y8tUIiiza1A?si=z90fuA2TN0tWfPXy
From an e90 but i think n52 and very detailed video will give you good heads up on solving your noise. He replaced his lifters which four were soft on initial exam.
I think the recangring are always locked to the cam and spin in place and logically you're correct that the gap will be where it wants to cause wear.
On the video he replaced the intake can shell from boneyard.
With no vanos errors I'd bet lifters are your noise source.
If you copy this video and discover no cam ledge problem just replace the seals with Teflon and change the lifters which are stupid easy compared to most where you need to release the valve spring.