I've seen oil smoke burn blue (in relatively small amounts) and white (in copious quantities) but I have never seen it burn black.

Are you using oil? How much blowby do you have when you remove the oil filler cap?

The crankcase needs to be vented somehow. Into the intake is as good as anything else.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13