I recently sorted out some issues with my w201 2.5 non turbo. It runs well does not smoke and starts fine even when cold. I have heard that the valves on these motors need adjustment every 20,000 miles or so is this necessary or is this something like if its not broke dont fix it

Hydraulic lifters. No adjustment necessary (or possible).

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1987 W201 190D

thank you very much

BTW, "Timing adjustment" would usually imply ignition or injection timing. What you are asking about usually would be called simply a "valve adjustment," sometimes "valve lash adjustment," or "valve clearance adjustment."

When work is done on the cam or timing chain, people usually say they've "set" the valve or cam timing, because it isn't really something that is readily "adjustable," like a normal tune-up or maintenance procedure. (Technically, it can be adjusted with offset keys, but I think you get the point.)

I'm not trying to be picky or anything, please don't get me wrong... just trying to avoid confusion.

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1987 W201 190D