Car show is over so this week I started the dismantling to get to the timing chain. Got the timing cover off this evening and found......a broken timing chain tensioner! These two pictures show it, the tensioner is a leaf spring with a double thickness which applies a sideways force to the chain, the leaf away from the chain broke off and was making the noise. That's why you see the two halves wide apart in these photos:
I had already bought a new tensioner and timing chain plus a few other parts. Turns out the oil slinger was damaged somehow, see picture below, so I'm replacing it too:
I plan to do some more detailing in the front engine compartment, esp removing overspray from paint job, before re-assembly so it will be a couple of weeks before I get it all put back together. But sure does feel good to find the root cause!
