I have a cousin that owns a 1982 300D. She purchased it in June and put 6k miles on it without ever opening the hood (lot's of pretty blond hair though). Anyway, she came in one day and told her husband that it had started a pretty good clanking/knocking noise. He went out and checked the oil and she had pretty much run it without the proper amount of oil. I went and took a look at the car yesterday and did a valve adj/compression test. The numbers on the compression test were 380 to 420 psi. The car starts/runs very good as indicative by the compression numbers but does have the knocking noise. Her husband (he is a very capable auto mechanic but does not know alot about diesels) and I agree that it is more than likely a lower end bearing issue. I offered to pull the engine and replace the bearings and told her that if she does drive it to failure then she will need to try to find a good used engine. The car is only showing around 140k miles. What do ya'll think?

__________________
Jim