The inexpensive test to determine the condition of a diesel engine is "will it start right up in cold weather (after sitting all night)"

Blow By is difficult to measure unless you are utilizing a spare home gas meter AND Mercedes has a spec for blowby in CFM (I just don't remember what my MB diesel mechanic told me).

The blow by could be caused by caked up rings from a poor oil change interval AND this sometimes can be reduced by utilizing synthetic oil over a period of time.

If the engine starts right up in cold weather, I wouldn't worry about the blow by. AND just because it doesn't start up in cold weather doesn't mean the blow by condition has anything to do with the problem.

(Now if you wanted to spend some money on a leak down and compression check, that would give you much more information as to the engine condition. But that wasn't discussed in your post) Thats the proper way to diagnois an engine's condition.

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84 300DT Puke Yellow. Totalled after 438,000
84 300DT Orient Red. 169,000 (actual mileage may vary)
2002 Explorer EB (wife's)