We have had a similar experience where some lifters failed and the thing made one hell of a noise. The other thing could be that some of that gunk broke loose from the EGR and is in the combustion chamber...
One more thing that I have seen is that the windage tray bolts will fall out inside the oil pan and kill the oil pump.
1992 500E (very soon I hope
1981 280GE SWB
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