you have no basis for that conclusion on someone else's vehicle.

I can confirm that at idle both hot and cold, there is no real blowby. The oil cap will not move, it just vibrates with the engine. There is oil mist from flinging off the cam I guess, but it is an oil mist (characteristic odor), not lots of combustion byproducts.

FWIW.

So Ive not seen any good plans for a catch can for a 123/617. I'd imagine it is the same as on a gasser, but I have no idea if it actually applies to a diesel.

Should the cyclone separator be re hilt/refurbished/modded? I'd like to take blowzy out of the equation before I attack the turbo...

Thanks!

Below is what I did.
Washable Air Filter and Intake Mod , With Larger Breather
http://www.peachparts.com/shopforum/showthread.php?t=280376

2 weeks ago I pulled off the Air Filter and the Plastic Inlet Tubing I made.
I washed the Air Filter and checked the Tubing for Oil.
Even with my mod there was a light coat of Oil in the Tubing.
But, the main thing is that none of the Oil got close to the Air Filter.

I tried to provide a larger expansion chamber so that the Oil would have more of a chance to condense but, even with the larger chamber some Oil vapor is still remaining and getting into the Air Inlet Tube.

The Cookie Can that I used was something I did just to get the job done and because I could not figure out an easier way to set up the Drain.

I think the keys to getting the Oil out of the Blowby are to slow the velocity of the moving Vapor and to cool the Vapor down so the Oil condenses back to liquid Oil.
Or pay the money for a commercial Filter that is designed to remove the Oil from Air.

My air filter does not get oily at all, it's just the dripping from by the turbo inlet?

That is good.
It used to be that about 4 inches of the Filter Element on mine would get stained by Oil.
In the pic below you see the liquid Oil I had at the top of the U-tube. There was more at the bottom where it attached to the Turbo.