<font color="blue"> If the oil is becoming diluted with fuel [ Which it sounds like ] perhaps a real checkup is in order at a proper Doctors office. </font>
Gets my vote!
The puffs coming out of the breather may be fuel vapor. The "puff rate," for lack of a better term, tends to indicate it is related to something driven off of the camshaft. Fuel may be getting into the oil through a bad injection or lift pump.
A qualified diesel mechanic should be consulted right away. There may be a risk of significant additional damage if the machine is operated in its current state.
If atomized fuel is somehow present in the crankcase, there could be a risk of explosion. I suspect the risk would be low, but it should be considered.