Assuming that is a hydraulic lifter, does it break and then cause the valves or cam to break... or does a valve get stuck and then the lifter gets crushed as the cam comes around? I guess I am trying to ascertain if bad lifters cause the problem or if they are just collateral damage. Thanks.

And sorry about the engine.

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1968 220D, w115, /8, OM615, Automatic transmission.
My 1987 300TD wagon was sold and my 2003 W210 E320 wagon was totaled (sheds tear).