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It’s currently a nippy 12 degrees out by me but the e39 starts up with ease. While driving around a thought came to me; what is the absolute coolest temperature it can be before a car will refuse to run? While google didn’t give me much, I remembered that on top gear the guys did a test to see how a Citroen c1 would fare in the cold. At around -17 degrees Celsius the engine, which ran on diesel, failed to start but was turning over. Clearly the diesel froze and couldn’t run the engine. Eventually the car’s electrics finally died and they ended the test. However I think it’s possible that the car’s battery just straight up died and caused the electrics to fail. So, given that a car has fluids that can withstand the cold temperatures and a sufficient power source that works in subzero temperatures when is it too cold to run a car? If I was to take a guess, it would have to be past the point where is so cold that the electricity of the car would stop flowing.


Owning a BMW is always interesting
 

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Nuclear engineer
02/2012 X5 35d M57Y CPO 99K miles NOKIAN WR G3 12K miles
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My TDI, at the time about seven years old, started at -35°F (~ -37°C) (IIRC °F and °C cross at -40) at 2200 during an extreme cold snap. The GP***8217;s were on for their full cycle duration, the crank was extended by one additional turn, and it grumbled and rattled for a minute before it settled down.

I spent a winter at Idaho National Engineering Laboratory while driving a 1200 cc MOWOG and observed -40°F out at the site, but never associated starting with temperatures, and the car started every time.

It is an interesting question. I know that machines in the Arctic and Antarctic are often maintained running for the full season.
 

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Got to -25 C (-10 F) in the greater Toronto area this weekend. -23.5 at start this morning. My x5d shuddered and shrieked but ignition fired at first attempt. Coolant per obd2 was -10 C (engine was on 16 h ago).
A decade ago, i had a vw tdi, coldest that started was -25 C. i recall power-cycling the glow plugs twice and using diesel treatment in that.
None so far for the x5d. No battery tender or block heater. Outside parking. Loud and slow but runs. IMG_20190121_073343.jpeg
 

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I had a friend who lived in Alaska, and he said during the coldest time of winter, the tires freeze, so the flat part of the tire which has been against the ground stays flat as you begin to drive. Then, the tires would rotate differently, so the car would drive down the street going “whop, whop, whop” until the tires warmed a bit and got their shape back.

During the winter, of course, cars had to be plugged in overnight to keep the engines warm and also to render the batteries. Crazy.
 

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It’s currently a nippy 12 degrees out by me but the e39 starts up with ease. While driving around a thought came to me; what is the absolute coolest temperature it can be before a car will refuse to run?
Don't have a specific value to answer your question, but 12° F (-11° C) ain't cold at all! ;)

F30 320d starting up in -32° C (-26° F):
https://www.youtube.com/watch?v=QxzrKuz3Qgo

Dodge Daytona with Mitsubishi 6G72 engine, starting up in -46° C (-51° F):
https://www.youtube.com/watch?v=2-NeWvAVNbs
 

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02/2012 X5 35d M57Y CPO 99K miles NOKIAN WR G3 12K miles
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Here's starting a big old diesel like I did my summer before college. Mine must have been a year or two newer because it was all done from the cab.
https://youtu.be/BHedjnXdZXM

Here***8217;s the ranch where I worked the summer before college in 1966. I worked for the Lester brothers and the little kids had grown by the time I knew them. There were a half-dozen of us college/bound kids that spoke Mexican that could help and interpret for the Mexican foreman. Good people.
https://youtu.be/8AujdPdpfHs
 

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IMG_6832.jpg

This was taken 2 years ago. This year has been warmer at just -25 at lowest. I have a CTEK battery maintainer built in to the car and I plug it in overnight otherwise the car will go into low power mode after starting and cut the power to the blower/heater. But whether it’s plugged in or not it fires up pretty damn good.
These cars are lucky that they don’t get affected by windchill, which sometimes reaches -50C




Sent from my iPhone using Bimmerfest mobile app
 

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As long as the combustion happens in sequence as it should, it should start. You can ignite gasoline in -80 degree weather if the air, fuel, ignition diamond is right. I would assume it would be restricted by the strength of the battery to roll and ignite it, the thickness of the oil to lube properly not restricting it from rolling. The general maintenance of the vehicle allowing it to come alive. Diesel fuel is another animal all together.
 

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Graphs at engine start this morning, x5d, outside parking.
Loud and shaky but starts without hesitation. Glow plugs symbol didn't display. Maybe cuz it took me 2 seconds to insert fob (i think glow plugs are activated on proximity of fob to dash to speed up compression ignition process). Or cuz LCD screen was too slow to show anything. Screenshot_20190131-072713.jpeg
 

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A trick i found useful, wish i knew last winter: for those of us without comfort access but with start button, as part of car pre-heat, u can start the car with the fob in dash (normal start), then take out the mechanical key out the fob, and lock the car from the outside with mech key, leaving engine/hvac to warm up car.
Ive been doing this for a couple weeks now before driving off to work.
Today, after 10 min of idling, coolant got from -13C to 35C.
 

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02/2012 X5 35d M57Y CPO 99K miles NOKIAN WR G3 12K miles
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You don***8217;t think that the engine and transmission will heat up faster under load driving?

Cabin temperature is not initially dependent on engine heat in E70 diesels as they have a 1000 Watt (80 Ampere) PTC cabin heater over which the operator has no control.

Many jurisdictions prohibit unoccupied idling warm-up.

A VW TDI will not warm-up idling and will cool from NOT to cold idling at a stop light.

In a few minutes I will go for a drive at -15°F.
 

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You don***8217;t think that the engine and transmission will heat up faster under load driving?

Cabin temperature is not initially dependent on engine heat in E70 diesels as they have a 1000 Watt (80 Ampere) PTC cabin heater over which the operator has no control.

Many jurisdictions prohibit unoccupied idling warm-up.

A VW TDI will not warm-up idling and will cool from NOT to cold idling at a stop light.

In a few minutes I will go for a drive at -15°F.
Yea but in my case, i gotta be at highway speeds in as close as 3 blocks from my house, so i refuse to do this without an attempt at some warm up.
Car runs quieter, gears shift faster, and is actually habitable inside it if i warm up
 

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Yea but in my case, i gotta be at highway speeds in as close as 3 blocks from my house, so i refuse to do this without an attempt at some warm up.
Car runs quieter, gears shift faster, and is actually habitable inside it if i warm up
Hi kozlio, doesn't Toronto have an idling control law, which limits idling to no more than one minute in a 60-minute period? Or is that only for Class 3-8 trucks and not passenger cars/light trucks?

 

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Hi kozlio, doesn't Toronto have an idling control law, which limits idling to no more than one minute in a 60-minute period? Or is that only for Class 3-8 trucks and not passenger cars/light trucks?

Have not verified. I recently moved to Pickering so im in a different jurisdiction now.

Without diverting from the topic of cold weather and low temp ignition, let’s not forget that livestock and their byproducts account for half of green house gas emissions worldwide, more than all forms of transportation around the globe. Therefore not eating animal products will make a bigger difference to the planet and our air, than pollutants from ever-more-efficient technology in cars and evolving environmental standards.
UN, 2006: https://news.un.org/en/story/2006/1...greenhouse-gases-driving-cars-un-report-warns
Env. Article, 2008: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2367646/

Ill continue warming up my car in subzero temps and u'll continue eating a burger ;)
 

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Personally I'd be less concerned with "Will my car start at -XX F?" than with "What damage am I doing to my journals, cylinder walls and various moving parts, starting the car with my oil at - XX F?" In fact, I'd be in favor of idling the vehicle not just to warm up the interior, but to get the oil up to operating temps before putting any load on the motor.

I'm surprised no one in the REALLY cold regions has an engine block heater, or one of these:

https://www.youtube.com/watch?v=G3taTuyVRKw
 

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02/2012 X5 35d M57Y CPO 99K miles NOKIAN WR G3 12K miles
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I'm surprised no one in the REALLY cold regions has an engine block heater, or one of these:
That I don’t have a block heater is not for lack of looking.

I had a 1,000 Watt Zero Start by Frost Heater on my TDI. It was a well designed and integrated thermo-syphon. There is no equivalent product for BMW’s particularly a diesel.

http://frostheater.com/

I discount the effectiveness of pan heaters and particularly dipstick heaters. They are too small to be very powerful, like a kilowatt.

A freeze-plug heater might work but for the mind boggling expense of getting to the BMW freeze plugs.

(Hmm. Here’s a refresh my memory issue. There is a physical law that tells why a 250 Watt human being doesn’t glow like a 250 Watt lightbulb filament - but would if shrunk to the same area.)
 
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