Here's some additional diesel starting weirdness..
1978 300D W123 154,000 miles....
No block heater(well, the new one is in the trunk)
Temperatures have been DAMN cold here (+10F in the mornings)
When I first glow to start.. car has been coughing and hacking like fuel is restricted or glow plugs are not working correctly. However, turn car off, re-glow immediately, car starts much more easily and gets to smooth idle right away. Any ideas? On the second glow, the glow light has been staying on for a few seconds as well after the car starts...... bizarre.
Also, for those who have slow cranking on cold mornings... A new battery and synthetic oil seems to make a HUGE difference. The car has been turning over almost as quickly as in warm weather. Nice.
Cheers and thanks to all.