I'm assuming you want to manually rotate the crank, and see if the distributer lags or not.

But I want to make sure. Exactly how qould you diagnose a stretched timing chain in a 450SEL? . . . as opposed to a loose tensioner?

And how can you differentiate timing chain slack as being due to the tensioner or the chain itself?

If EITHER the chain or tensioner is bad, do we want to replace BOTH tensioner and chain, or just replace the part?

Thanks for any insights...