You've got a vacuum leak somewhere if it is not shutting down with the key. I would concentrate on that first.

I would leave the clattering/smoke alone for a while after fixing the above and see if having lowered the oil to the proper level and fixing the vacuum leak doesn't slowly improve things.

Is also quite possible you are hearing injector noise too rather than valves. I've been fooled twice by injector clatter sounding like valves. Diesel Purge (2 cans at a time) helps and is probably a good investment before jumping off into other more expensive fixes.

__________________
Terry Allison
N. Calif. & Boca Chica, Panama

09' E320 Bluetec 77k (USA)
09' Hyundai Santa Fe Diesel 48k (S.A.)