Are the glow plugs working? I would not have released the starter as soon as you did. I would have helped it run with the starter for a number of seconds to get it running well before disengaging the starter. It behaves exactly like a diesel trying to start at 25 degrees below zero which makes me suspect bad glowplugs. I'd also consider giving it a separate fuel supply in a gallon jug to rule out any fuel delivery problems from the tank.

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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