A few weeks ago, I changed my timing chain because I knew it was stretched and there was a ticking sound coming from the camshaft sprocket area. As I rolled out the old chain, I found the master link part almost totally disintegrated. Only the middle link was still holding the chain together. Here are some pictures of the timing chain master link area after I removed it from the engine.
The top picture shows the front view of the master link which is missing the circlip part.
The middle picture shows the rear view of the master link with a (busted link)
The lower picture shows the master link part along side the center link that held the chain together for I-don't-know-how-long. Notice the oval holes worn in the center link part. The wear in these parts allowed the chain to flop outwards on the camshaft sprocket about 1/8", which explains the ticking sound I heard.
The chain pins have worn heads showing that they have been wearing on something (maybe the chain guides), preventing them from sliding out. It seems like this master link is the kind with the circlip end, not the peened end type.
I didn't see any damage to the upper chain guide, the banana tensioner slide or the tensioner. All seemed to be OK. The ticking sound is gone. I guess this is what these chains look like just before they disintegrate.
Had I known that the master link was this bad, I could have saved the hassle of grinding a swaged link away to get the old chain apart. I could have just pulled the master link out with my fingers.
1979 300D with 120k mi, but I suspect the odometer has been rolled back.