Timing chain rattle will make a very distinct sound that lasts maybe ten seconds on a cold start.

The start noise is not a big problem it's just the clue there is one.

When the tension is loose the chain will come off the guides and slap back on likely when you hit a bump or off throttle.

I've seen mention of 400,000 miles on original guides so it's not inevitable. I'm confident that most chain guide failure is from keeping a worn out tensioner too long.

I will be changing them on wife's 50i before 100,000 miles for sure.

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2011 E70 • N55 (me)
2012 E70 • N63 (wife)