M42 timing chain rattle...revealed!
Started having a pretty nasty rattle from 2800-4200 rpm in the 318is. Pretty day today, dove into it. Found a few issues...tensioner rail worn at the top. Bottom guide cracked around one lug. Chain might be a tad stretched. Idler gear looks good, cam gears look good, crank sprocket looks good, long guide looks good, top guide looks good but is $6 to replace. I think I'll replace the chain, update the tensioner to the late M42 version, replace the upper and lower guides and all gaskets, and let her rip. Picture of the cracked lower guide attached.
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