Late injection timing or a toasted IP.

Check timing chain stretch, make sure you actually have valve clearance on all the valves, set start of injection.

The sudden occurance bothers me, it's very unlikey this is low compression appearing suddenly UNLESS you set some intakes to exhaust clearance and vise versa (don't ask how I know this!).

Later model 617's have a crankcase vent for the vac pump, they won't blow oil down the intake, and that's blue smoke, not white.

There is also a possibility you have a couple of bad injectors that are squirting fuel instead of a nice mist, but they should knock pretty bad if they do.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!