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

You CAN leave it plugged in all night but you only need to run the block heater for 3 hours or so, even in the coldest weather. So if you have a heavy duty timer you can use that if you like to save electricity. No harm will be done by running the heater all night.

To check if it's running, open the hood, put your head down over the engine and listen carefully. You should hear a hissing or singing noise rather like when an electric kettle is starting up.

I ALWAYS unplug the heater before starting simply to avoid the problem of driving away in a forgetful mood with the cord still connected to the power plug, with obvious side effects about to happen in 0.5 to 1 second. Don't ask me how I know this!!!!!!

PS you DO have synthetic engine oil?

Cycle the glow plugs one full time and start it about 20 seconds into the second cycle, if they are good the car should start. Even if one glow plug is bad it won't start at that temp.
Cars don't feel windchill fortunately. Use thin oil.

Do a search for cold weather starting techniques.

Drape the extension cord over the hood star or rear-view mirror.

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1980 300 TD

1997 Dodge Pickup/Cummins 5.9 12-valve

The heater only draws about 4-5 amps (500 watts) so you really do not need a heavy duty timer. Just about any timer yiou buy is rated for at least 10 amps. Make sure you read the package or the back of the timer.

I use the "Drape the cord around the star" method.

-Jim

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1995 S350D, Green with black leather interior.
Bought January 2008 w/ 233,xxx miles.
I did 22,000 miles during the first year of ownership.