Thanks for the info on the compression test. I have moved from worry to curiosity. Next time I have the valve cover off I will investigate further this odd occurence and will take some measurments. That will be in 12K miles or so...

Rusty

I too agree with Brian in that it is more just an effect. Probably typical with some wear rather than a problem as such.
At around two hundred thousand miles as several of my cars indicate or more. It seems reasonable to expect some of my fairly good engines would display simular results if I duplicated what you did. There will of course be some wear evident amoung the various components. That is to be expected.
The engine will let you know when too much has occured at some point in the distant future. I was just speculating on perhaps the cause of your effect.

I agree its just normal wear, which is part of the reason you try to avoid rotating the stems, as it disturbs it's "natural" pattern and can possibly cause undesirable results. Some manufacturers (Chevy and Ford) that I know of, actually addressed this problem by incorporating valve rotators under their springs, with a lobe that struck the valve lifter in an offset area, so as to make the valve spin as it actuated each time, theoretically causing it to not create a one spot wear pattern. MB didn't do that with these engines, causing that exact situation, which isn't really a problem, but could cause a shorter lifespan between valve jobs.

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Chris
64 190D R.I.P.
80 240D W/617 engine -for sale
82 240D -for sale