Pull the dipstick or the oil-fill cap when the engine is hot and idling to get a sense of the blowby effluent being passed into the turbo inlet - higher mileage or abused engines will have increased blowby
The
Crankcase
Depression
Regulator cannister doesn't block oily crankcase blowby vapor unless the airfilter is so dirty that intake vacuum has increased to the point where raw oil will be pulled outta the valve cover - it is straight-thru unless high-vacuum closes the diaphragm - no magic, there - normally, the hot oil-laden vapors pass directly thru into the turbo inlet, aided by blowby pressure, and the dense oil has little opportunity to precipitate out, which is good, as those oily vapors contribute to fuel economy (Diesel engines do burn oil, right?) - however, in winter climes ambient inlet air temps are way cooler, making the inlet path cooler than in summer, wherein the oil-laden vapors cool quickly, allowing the heavy oil component to condense and drop out of the crankcase effluent - thus, you will notice more oil in the inlet plenum in winter, less in summer - quantity depends on engine wear, of course
The
CDR in the early 6.2
Closed
Crankcase
Ventilation systems was part of the oil-fill tube and had condensing mesh in the cap - those required cleaning @~30kmi
The '89
^ CDR is of different design, which may require cleaning at 60kmi if varnished-up - if not, no cleaning is necessary - those in deep winter climes may fail when the steel spring rusts
Again, visit the Mann-Provent or Racor sites for most excellent EPA-approved
CCV solution to oily intake
Here's a shot of the Provent install in my CRD KJ - Provent cannister is at upper left - upper hose from the CDR on top of the valve cover, upper right - lower hose back to turbo inlet - the clear section will indicate any oily blowby that gets thru the Provent cannister - notice it's clear and un-stained - drain is returned to crankcase
