I feel rather stupid but I found the problem after inspecting a new set of rings. The drainback groove openings in the oil rings were so badly plugged that it was not obvious that there were any openings. It required considerable scraping to expose the opening. We did try some cleaner prior to teardown but it would be virtually impossible for any solvent to remove this carbon. There is no doubt that a new ring set will restore this engine to normal for many more miles. I guess it is possible that this engine was overheated earlier in its life to cause such severe carbon buildup. It has had regular oil changes over the last 90000 miles and the interior of the engine was very clean.
[This message has been edited by Webmaster (edited 02-21-2000).]