For a motorist, winter is always a test of equipment’s strength, especially when the thermometer drops below critical levels. Cold engine start becomes a daily routine, which requires the car owner not only to have a working battery, but also to understand the physics of the processes occurring in the engine. During sudden cooling, metal parts shrink, and motor oils lose their fluidity, turning into a viscous substance, which creates enormous resistance to rotation of the crankshaft.
Car owners are often faced with a situation where the starter barely cranks the engine, and the spark plugs are flooded with fuel due to ineffective mixture formation. Diesel engines in this regard, they suffer even more, since fuel ignition occurs from compression, and heat loss through the walls of the combustion chamber in the cold makes starting almost impossible without prior preparation. Understanding these nuances allows you to avoid fatal mistakes that can lead to major repairs or replacement of expensive components.
There are many myths and misconceptions about how to properly prepare a car for winter use and what to do if the car does not start the first time. Some drivers heat the pan with an open fire, others pour boiling water over the intake manifold, not realizing the risks that such methods carry. In this article we will look at time-tested and scientifically proven ways to ensure reliable starting the internal combustion engine in extreme conditions.
The physics of a cold start and the effect of temperature on components
When the ambient temperature drops to -20°C and below, the physical properties of materials and liquids change dramatically. Motor oil thickens, and if in summer it is pumped through a pump in a split second, then in cold weather this process can take several minutes, during which the rubbing parts work in dry friction mode. This leads to accelerated wear of the plain bearings, piston rings and camshaft.
The battery also loses its capacity: at -20°C, the output of a lead-acid battery can drop by 40-50% of its nominal value. Chemical reactions inside the cans slow down, the electrolyte becomes more viscous, which increases internal resistance. Combined with increased force on the starter shaft due to thick oil, starting current reaches maximum values that an old battery is not always capable of.
⚠️ Attention: An attempt to crank the starter for a long time (more than 10-15 seconds) in the cold can lead to overheating of the electric motor windings and melting of the insulation, as well as deep discharge of the battery, after which it will be impossible to charge it.
Particular attention should be paid to the condition of the spark plugs. Carbon deposits formed during the warm season can become a current conductor in cold weather, causing a breakdown to ground. Spark plug gap also plays a role: too large a gap will require a higher voltage to spark, which an ignition coil weakened by frost may not provide.
Selection of engine oil and technical fluids
The basis for a successful winter start is the correct choice of engine oil. The viscosity of the oil is indicated according to the SAE classification, and for winter operation the first index before the letter W (Winter) is critical. The lower the number, the lower the temperature the oil remains fluid. For regions with harsh climates, the optimal choice is synthetics with an index 0W or 5W.
Oils marked 10W and higher at temperatures below -25°C turn into a kind of tar, creating a load on the starter that it often cannot overcome. Synthetic base oils have better fluidity compared to mineral and semi-synthetic analogues, which ensures lubrication of components in the very first seconds of engine operation.
Use the oil dipstick to check the condition of the oil: if on a cold engine the oil does not drain from the dipstick, but stands in a “column”, starting the engine is strictly prohibited without preheating the crankcase.
Don't forget about other technical fluids. Antifreeze must have a freezing temperature margin of at least 5-10 degrees below the expected minimum. Frozen coolant can rupture the engine block or radiator, turning a starting problem into a disaster. Brake fluid is also hygroscopic and can crystallize in cold weather if there is a lot of water in it, which is dangerous for safety.
Preparing the battery for the winter season
The battery is the heart of the starting system, and its condition must be checked in advance, before the first frost sets in. The electrolyte density in a fully charged battery should be 1.27-1.28 g/cm³. A decrease in density indicates a discharge, which will inevitably lead to freezing of the electrolyte and destruction of the plates during strong cooling.
If the car is stored in an unheated garage or outside, it is recommended to remove the battery at night and bring it into a warm room. This is a simple but effective way to conserve charge and increase starting amps. The battery terminals must be cleaned of oxides and tightly tightened, as poor contact increases resistance and reduces the efficiency of transferring energy to the starter.
- 🔋 Check the charge level with a voltmeter: voltage below 12.4 V indicates insufficient charge for a reliable start.
- ❄️ Keep the battery case clean and dry to avoid current leakage through surface contaminants.
- 🔌 Lubricate the terminals with special grease or technical Vaseline to protect against corrosion.
Modern calcium batteries are less demanding on maintenance, but they are susceptible to deep discharge. If the car has been parked for a long time and the battery has reached zero, it will be extremely difficult to restore its capacity. AGM batteries, often used in Start-Stop systems, are more resistant to cycling, but also require careful handling and high-quality charging.
Engine Preheating Methods
To make starting easier in severe cold, engineers and car enthusiasts have developed various heating methods. The most civilized and safe way is to install a pre-heater that runs on fuel from the car’s tank (for example, Webasto or Hydronic). Such systems warm up the antifreeze that circulates through the cooling system, warming up the engine and interior before starting.
A more affordable option is electric heaters built into the cooling system or installed on the oil pan. They operate from a 220V network and require an outlet in the parking area. Heating the oil in the sump significantly reduces the viscosity of the lubricant, making it easier to crank the crankshaft and ensuring a quick supply of oil to the rubbing pairs.
⚠️ Attention: The use of open fire (blowtorches, torches) to warm up the sump or fuel lines is strictly prohibited! This can lead to ignition of plastic, rubber pipes and a fire with an explosion of fuel vapors.
There are also thermoses for antifreeze that allow you to keep the engine warm for 20-30 hours, but their effectiveness depends on the quality of the insulation of the engine compartment. Insulating the engine itself (“blanket”) helps retain heat longer after a trip, but does not warm up a cold engine. A combination of methods gives the best results.
Algorithm for proper engine starting in winter
The startup process should be consistent and smooth. First you need to turn on the low beam headlights for 10-15 seconds. This will start chemical reactions in the battery and warm it up a little. After turning off the light, you should squeeze the clutch (on a manual transmission) or press the brake (on an automatic transmission) to break the connection between the engine and the transmission and reduce the load.
For diesel engines, you must wait until the glow plug warm-up indicator goes out. In cold weather, the warm-up cycle may take longer, and some systems do several cycles in a row. Don't rush and turn the starter ahead of time.
☑️ Winter launch checklist
The starter should be turned in short bursts of 5-10 seconds with pauses of 30-60 seconds. This time is necessary for the battery to restore its chemical potential. If after 3-4 attempts the engine does not start, further actions may be useless or even harmful. You need to let the battery rest for 10-15 minutes.
After a successful start, you should not immediately give high speeds. Idling in the first minutes it is necessary to warm up the oil and equalize thermal gaps. However, long-term parking with the engine running (more than 10-15 minutes) without moving is not recommended, since the engine may not reach operating temperature conditions, and the condensate in the exhaust system will freeze.
Features of starting diesel engines
A diesel engine is more demanding on the temperature in the combustion chamber, since ignition occurs from compression. At low temperatures, the air in the cylinders does not have time to heat up to the auto-ignition temperature of the fuel. Therefore, the serviceability of the glow plug system (calorizers) is critical.
In winter, fuel quality is extremely important for diesel engines. Summer diesel fuel at temperatures below -5°C becomes waxed, clogging the fuel filter and lines with wax crystals. Usage depressant additives or switching to winter/arctic diesel fuel is a mandatory condition of operation.
| Parameter | Gasoline engine | Diesel engine |
|---|---|---|
| Flash point | From the spark of a candle | From compression (temperature) |
| Critical element in winter | Spark plugs, battery | Glow plugs, fuel |
| Start-up risk | Filling spark plugs with fuel | Non-ignition of the mixture |
| Warm-up time | Less | More (cylinders need to be warmed up) |
If the diesel engine does not start, you can try using the “Quick Start” aerool (ether-containing mixture), injecting it into the intake manifold. This will increase the cetane number of the mixture and make it easier to flare. However, this method should not be abused, since sudden ignition of a large amount of ether can damage the parts of the piston group.
Typical mistakes and their consequences
One of the most common mistakes is trying to “light” a car with the donor engine running. In modern machines with complex electronics, a voltage surge when connecting or disconnecting wires can damage the engine control unit (ECU) or other sensitive modules. The correct sequence of actions when lighting a cigarette must be strictly observed.
Another mistake is starting the engine “from a pusher” on a slippery road or with cold oil. This creates shock loads on the timing mechanism and can lead to the chain or belt jumping, which will cause the valves to meet the pistons. For modern engines with hydraulic compensators and phase shifters, this starting method is disastrous.
Why can't you crank the starter for a long time?
During prolonged operation, the starter consumes a huge current (up to 300 Amperes). This causes the windings to heat up and can lead to an interturn short circuit. In addition, the electrolyte in the battery boils, the active mass of the plates crumbles, and the battery fails without the possibility of recovery.
Ignoring signs of malfunction in the summer (hard starts, tripping) will definitely come back to haunt you in the winter. Weak compression, which was compensated by high speeds and warm air in the summer, will become fatal in the winter. Therefore, autumn diagnostics is not just a recommendation, but a necessity.
The main key to a successful winter start is comprehensive preparation: a working battery, oil of the correct viscosity and high-quality fuel. No “emergency” method can replace regular maintenance.
Frequently asked questions (FAQ)
How long should you warm up your engine in winter before driving?
Modern engines do not require prolonged warm-up in place. 2-5 minutes are enough for the oil to disperse throughout the system and the speed to drop slightly. Further warming up is more effective while driving at low speeds, without sudden acceleration.
Is it possible to add gasoline to the oil to make starting easier?
Absolutely not. This is an “old-fashioned” method that will lead to a decrease in the lubricating properties of the oil, scuffing of the crankshaft liners and engine failure. Modern 0W oils already contain the necessary additives.
What to do if the battery is completely discharged in the cold?
If the electrolyte in the battery is frozen (the case is swollen), it cannot be charged - it may explode. If it just sits down, it needs to be warmed up in a warm room to room temperature and only then charged with a low current.
Is it true that synthetic oil burns more than mineral oil?
No, it's a myth. High-quality synthetics have a more stable molecular structure and evaporate less at high temperatures, and in the cold they provide better protection than mineral analogues.