Hi everyone I am trying to diagnose the following problem and need some help.

1983 300SD. Had some nailing at low speeds (first gear only). I took all of the injectors out and soaked them in gumout overnight and replaced them. I did my first valve adjustment (was easier than I thought). The timing chain was not streached more than 2 degrees (286,000 miles). The valves had not been adjusted for at least 100,000 miles and were so tight that I could not fit anything through them.

The car starts up much quicker and idles better however I still have the nailing sound at low speeds and alot of strange clanking coming from the front of the engine at idle. I took it out for a test drive and at one point there was a loud thumping sound for a few seconds that went away when I reached 10 or 15 mph.

I am reading all of the posts and I am getting confused with the harmonic damper, spun bearings, cracked crankshaft or just new injectors. How do I eliminate these to find out what is wrong. Could a bad injector cause this? I would hate to go out and spend $300 to find out I did not need them.

Aloso can I do any bottom engine work without removong the engine if this is needed?