240D Cold Start?

Question for the board:

I have a 1976 240D with 340k miles. It seems that every time the ambient outdoor temperature slips below 75F, the car will not start or takes a very long time to start. The situation becomes worse if the car sits without running for more than a few days while the temp is below 75. I replaced the glow plugs today to no avail. I've tried using the block heater, but this appears to have no affect. The only correalation I have found to this car not starting is the temperature. It starts fine in any condition during the summer months. Thoughts?

Todd

Low engine compression?

[MikeTangas]

When were the valves adjusted last? Possible source of low compression.

LOW COMPRESSION WILL MAKE FOR HARD STARTS BUT IF IT STARTS AT 75F IT SHOULD START AT 65F.
CHECK THE FOLLOWING,VALVE ADJUST(OLD TIRED DIESELS LIKE AN EXTRA .002 IN. ON VALVE CLEARANCE IN COLD WEATHER)
WHILE THE VALVE COVER IS OFF SET THE CRANK TO TDC #1 AND SEE IF CAM TIMING IS CLOSE(IF CAM TIMING IS OFF SO IS PUMP TIMING) MAYBE TIME FOR NEW CHAIN.
BLOCK HEATER SHOULD BE O.E. TYPE OR SIMILAR(SCREWS INTO BLOCK, NOT IN HOSE.
ONE LAST THOUGHT! OTD'S CRANK FASTER WITH CLEAN FRESH WINTER GRADE MOTOR OIL.
MF

Thanks for the fast replies, guys.........

The chain was replaced less than 1k miles ago. I would not know what the compression is without taking the car to a mech. I suspect that it has been quite some time since the valves were checked last, however, this should have been completed when the chain was replaced?. Current oil is fresh Castrol 10/30. North GA climate this time of year is upper 50's for highs and lower 30's for lows, typically.