I've recently purchased a lovely black/black '89 560SEL with rather high miles (424k) under the pretense that it needed a timing chain. It has a constant clack that is present on cold starts, hot starts, and during operation. I maintain my belief that the noise is from the timing chain, however a friend mentioned that the issue could be a lifter.

Based on the assumption that the issue is timing chain related, I swapped on a used spare tensioner, to no avail. I assume that either A. the used tensioner was worn also, or B. my chain is so stretched that any normal amount of tension would be insufficient. I'm a bit conflicted with purchasing a new one when I inevitably do the chain, because it seems that the FEBI part is of very inferior quality and a new MB part darn near totals my car haha.

The link below is a video of the engine idling and I assure you there will be no problem hearing the noise.
https://youtu.be/pjyHeQFBVdo

Thanks all for any input!

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1986 190E 2.3-16 202k
1987 300SDL 384k
1987 300SDL 295k (1 of 1 Dark Green over Maroon)
1988 300TE 129k (sold to buy cossie)
1989 560SEL 424k
1990 560SEL 288k (sold)
1992 300E 131k