Barry,

Thank you for your very thoughtful response - I appreciate your help. I am pretty sure that I am dealing with the original chain (I have talked with the last 2 owners), so I am going to change it (275,000 - 300,000 miles on the car).

I am not sure as to the pinging and the advancing/retarding of the timing - and I don't know why it occurred all of a sudden. I thought that it could be related to bad diesel at some point on the trip home to Ohio, but the problem has persisted. The timing chain stretch has DEFINITELY showed some change over that past 2500 miles - again I don't know why, but I do know that I used the same procedure to check (and re-check and re-check) both times.

I am going to change the tensioner - do I need to change the tensioner rail? I have tried to look at mine as best I can (I know it's difficult with the old chain still there) but it looks fine.

ryan

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RG Newell

1984 300D
1972 250
1986 560SL
1991 300CE