* Thickened Oil: The most significant factor. At sub-zero temperatures, engine oil becomes extremely thick, almost like honey. This makes it difficult for the oil pump to circulate the oil properly. Without sufficient lubrication, the engine experiences increased friction, making cranking difficult and potentially causing damage.
* Battery Performance: Cold temperatures reduce battery performance. A partially discharged battery, already weakened by age, has even less power available to crank the engine against the increased resistance of the thick oil.
* Fuel System Issues: While less critical than the oil, fuel can also be affected by cold temperatures, potentially leading to vapor lock or difficulties in atomization. This can slightly reduce combustion efficiency and contribute to starting problems.
* Increased Metal Contraction: Metal parts in the engine contract in the cold, creating tighter tolerances. This adds to the resistance the starter motor must overcome.
The block heater addresses these issues by warming the engine block and the oil within it. This reduces the viscosity of the oil, allowing for easier cranking and lubrication. The warmer engine also helps the battery's performance by reducing the load during starting. A few hours plugged in is typically needed to make a significant difference in the engine's temperature and oil viscosity.
In short, the combination of extremely thick oil, reduced battery power, and the overall effects of cold on the engine's mechanical components make starting nearly impossible without pre-heating the engine block.
