Car Problems With Sub Zero Temps

Extreme cold be hard on anything -- including your car.

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The Arctic Circle may not be getting any closer to most of the planet, but try telling that to the people who must endure northernmost climes on a regular basis. For them, the words "bone-chilling cold" fall far short of describing the metal-shattering extremes of mid-winter. While few autos on Earth can bear the brunt of all that mother nature can dish out, it's best to know what will happen to the typical auto during those deepest of deep freezes.

Related Searches: The Nature of Hot and Cold

Absolute zero: It's more than just negative 459.6 degrees F. It's the black hole of thermodynamics, a sort of bizarro world where atomic movement ceases, metals pass electricity with infinite efficiency, and frozen gases become quantum super fluids. To simplify, think back on Newton's Laws of Inertia; objects in motion will tend to stay in motion, while stationary objects will resist motion. If you reduce movement at an atomic scale, then any kinetic energy that impacts the cold object will unevenly transfer its energy to the object; atoms near the impact will try to move to absorb the energy but will smack into the stationary ones. The result is a loss of atomic cohesion and shattering of the object.

Rubber and Synthetic Rubber

Rubbers materials are some of the first to suffer in the intense cold. By definition, they depend on molecular flexibility and elasticity to do their jobs. They do this by cross-linking long chains of "coiled" molecules into a matrix called a polymer. Think of it as a cargo net made out of a bunch of very long Slinky toys instead of rope. Once atomic movement slows down, those coils will resist uncoiling and snapping back into place. Rubber will start to grow progressively harder until about negative 20 degrees, when it may retain elasticity comparable to PVC plastic. Prolonged exposure to temperatures like these will break enough of the polymer chains to permanently damage the rubber. Around negative 60, rubber has lost almost all of its flexibility and is one sharp impact away from cracking or shattering.

Metal

Metal's crystalline structure causes it to react to extreme cold a bit differently than rubber. Spring-steel components will progressively lose their springiness down to a temperature determined by the specific alloy composition, generally becoming brittle enough to snap at somewhere near negative 60 degrees. Harder structural and bolt steels, which by nature are already more brittle than spring steels, will tend to snap at higher temperatures. Frame cracking is a well-known problem among heavy haulers that run the ice roads of Canada and Alaska, where temperatures may not see anything higher than negative 10 for months. Metal also contracts when it gets cold, which increases clearances between components and can cause fasteners to literally fall out of their holes. Leaking seals and coolant lines, excess bearing clearances and breakage between gears made of different metals are just a few of the many other resulting problems.

Fluids

Russia's winter may make it an unpleasant place to be most of the time, but it's also saved the country on more than one occasion. The arctic nation's brutal winter all but froze Hitler's mechanized invasion in its tracks -- literally. German crews wrote much about having to build nightly fires beneath their vehicles' engines to keep the oil from freezing, which would have begun around 0 degrees. Typical automotive antifreeze is good to about negative 40 before it freezes solid, but that probably won't matter below about negative 20 anyway. Fuel's vaporization rate and volatility decrease with temperature, which is why you can smell a gas station two blocks away in the summer. At sub-zero temperatures approaching minus 20, fuel may lose so much of its volatility that you might as well run water through the motor for all the good it'll do.

Batteries

Batteries are finicky things, like little ecosystems themselves. They're engineered to strike a balance between going completely inactive and exploding, and those extremes are almost entirely dependent on the battery's temperature. Average battery amperage capacity and output drops by about 20 percent at 32 degrees, and it drops to about 50 percent at between zero and negative 20. By negative 40, the battery is effectively dead or likely incapable of overcoming the resistance of the syrup-like oil in your crankcase.

Tire Pressure

Keep a close eye on your tire pressures if you do manage to get the car started; air, like metal, contracts as it cools. The rule of thumb is a 1 psi drop for every 10 degrees. So, if you put 25 pounds in the tire in your 80-degree garage, pressure will likely drop to about 15 psi at negative 20 degrees.

ReferencesRace Car Engineering and Mechanics; Paul Van ValkenburghThe Mechanics of Materials; Gere and TimoshenkoThe Defense Technical Information Center: US Army Developmental Test Command Operations Procedure; Cold Regions, Material EffectsPhoto Credit Jupiterimages/Photos.com/Getty ImagesRead Next:

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