I know, it's not detonation in a diesel engine. But that's about the most accurate way I can describe what's going on with my 85 300 wagon. If it were a gasoline engine, I would say the timing was way too advanced (pinging in a conventional piston engine). It starts perfectly, idles well, and gets about 24mpg all with 275k, but has been making much more than usual diesel clatter over the past month or so. Seems a bit worse when cold, better after running 10 minutes or so. When more throttle is applied, the clatter is worse. Part throttle or lift off, the clatter eases. Haven't used any injector cleaner recently but have in the past. Does my injection pump need adjusting? Other thoughts? Thanks in advance...