[Boxstard]

Originally Posted by thom4782

My best guess is: worn chain tensioners, worn chain rails, or worn vairocam rails if your car has them. Could be all three. It could also be stretching chains.

Have you checked camshaft deviations and, if so, do you have past numbers to check them against. I believe changing deviations over time suggest wearing rails or stretching chains

You could also check the sump for black or brown plastic pieces to see if the rails are wearing.

Tensioners are cheapest to replace; variocam rails next and internal chain rails are the most expensive requiring a complete tear down.

Thanks for sharing your thoughts. I have zero chain rattle at cold start-up, that really puzzles me to doubt tensioners/ rails. 3 oil changes in the past 15K miles of my ownership came out with zero plastic or metallic debris in oil filters, but it is due now so I’ll check it out again. My car has 85K miles and it runs like a champ and revs smooth beside this strange, very isolated noise.

I never checked cam deviation, I’ll look into it. Anybody here around Detroit with the proper scanner? I got Autel with no such ability...