It’s not terribly difficult to do a tuneup on a Detroit, but you really must have a manual. Or have done it quite often and remember.
Best idea is have the manual and someone to who’s done it often walk you through it with the manual, then next time you can do it with the manual.
White smoke could be an indication of stuck rings or other troubles.
First see that it has fresh fuel and filters and the oil and coolant stay in their places, then run and work it for a while and see what clears up.
