The block heater on my daughter's 1982 240D has never been used before. Now that it's being parked outside we need to use it. This morning the temp was 2 degrees F with a wind chill of 27 below. Her car wouldn't start. I know it's not the car because it has a new battery, diesel fuel additive, etc...

My question is....is it simply a matter of leaving the car plugged in overnight? Can it stay plugged in all night? Do I leave it plugged in when starting the car in the morning then unplug it once the car has started?

Any and all advise is greatly appreciated cause I'm clueless when it comes to block heaters.

Thanks,
Freezing in Kansas

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1973 280 - Sold
1980 300SD - Sold
1982 240D - Stolen
1988 300E - Sold
1989 260E - Sold
1989 560SEL
1994 E420 - Sold
1997 E420
2005 CL500