Why Won’t My Car Start in the Cold?
There are quite a few reasons why your car won’t start in the low temperatures, all of which are equally frustrating when you are left standing in the cold. Low temperatures put considerably more strain on your vehicle’s mechanical and electrical systems, making them more prone to failure. After this blog, you should be able to diagnose why your car is not starting in the cold weather, as well as know how you can avoid it.
Reasons Your Car Is Not Starting in the Cold Weather:
When the temperature drops, your car takes considerably longer to warm up, making it harder to get moving and on with your journey. Here are some of the main reasons why your car isn’t starting:
Thickened Oil
Engine oil becomes thicker in freezing temperatures, making it considerably harder for the engine to pump oil through the block. For your car to start, oil must be pumped through the block, and the thicker it is, the harder the starter motor needs to work to overcome this.
One easy way to avoid this is by regularly changing your vehicle’s oil. Fresh engine oil lacks the dirt and sludge that causes older oil to thicken excessively in the cold. By maintaining its correct viscosity (thickness), it reduces the strain on the engine’s internal components, allowing the motor to turn over with less resistance. This is also beneficial to your car’s battery, as it will require less power during a cold morning to start the engine.
Fuel Evaporation (Petrol Engines)
In a petrol engine, the fuel needs to be turned into a vapour to ignite. When it is freezing outside, petrol doesn’t vaporise as easily. This makes it much harder for your spark plugs to ignite the fuel-air mixture and therefore start your car. Not only might the engine struggle to vaporise the petrol, but it can condense on the cold metal walls of the engine cylinders, which then starves the engine of the combustible gas it needs to fire up on a cold day.
To give your petrol car the best chance of starting in the cold, we recommend that you maintain your spark plugs, which means replacing them every 30,000 miles. As this gives you the strongest spark possible, which is essential when it’s freezing outside. We would also recommend you keep a full tank where possible. A near-empty tank has more room for air, which leads to condensation. This additional moisture can freeze your fuel lines or contaminate your petrol, which again makes the vaporisation even more difficult.
Fuel Gelling (Diesel Engine)
If your diesel car won’t start in the cold, it is rarely about evaporation, like petrol engines. Instead, it tends to be because the paraffin wax in diesel fuel has turned from a liquid to a waxy gel due to the cold temperatures. A gel is much harder to get around the engine, and it can clog the fuel filter and engine injectors.
When starting your diesel car in the cold, you should wait for the “coil” light on your dashboard to go out before you crank the engine. This indicates the glow plugs have heated the combustion chamber enough for fuel to ignite.
Electrical Resistance
The cold air temperature slows down the chemical reaction inside your car’s battery, which reduces the power it can output. This causes issues since the cold conditions also require more power output from the battery to get your engine running.
The main way to combat this is by ensuring all the electrical connections in the engine are strong, so the maximum amount of power will reach the starter motor without being lost to resistance. This means tightening clamps and cleaning terminals, as these both can increase resistance further.
Car Battery Won’t Start In The Cold:
As mentioned, the increased oil viscosity in colder temperatures requires more power from the battery. This is then compounded by the heightened demand for electrical energy for heating and lighting in the winter, which further depletes the battery’s charge. If you think your battery is the main reason for your car not starting, you should first consider its age and condition. Unsurprisingly, older or compromised batteries are more likely to fail in cold temperatures.
How To Prevent A Dead Battery In Winter:
There are a handful of things you can do to preserve your battery in the winter, but also prolong the life of your car, including:
- Regularly check, maintain and charge your battery
- Use the correct engine oil
- Cleaning/ inspecting the battery terminals
- Avoid short trips
- If possible, park indoors
The Role Of Summer On Your Battery Health
You might be surprised to discover that a lot of battery issues that come to light in winter were caused in the summer heat. Not only are winter checks important for your car but regular maintenance in the summer is also important. The high temperatures of the summer accelerate battery corrosion and can evaporate the electrodes within the battery. This damage weakens the internal structure of the battery, reducing its ability to hold charge and the power it can output.
What If Your Car Turns Over But Does Not Start In The Cold?
If your car is turning over in the cold but not starting, your battery is fine, but the fuel or spark is failing. It could be that the fuel lines are blocked, or it could be that the fuel won’t ignite.
For a petrol engine, you can turn your ignition on (without cranking) a couple of times. This forces the fuel pump to prime the system, ensuring maximum pressure to help the injectors vaporise the fuel better.
For a diesel engine, the fix is not the same; you should wait for the glow plug light (orange coil symbol) on your dashboard to disappear. When it is really cold, it can be worth letting the light disappear and then turning the ignition off and back on and letting it disappear again. This ensures that there is enough heat to try to start the diesel engine.
When trying to diagnose any problem with your car, it is important to keep in mind all of the engine warning lights, as these can help you narrow down any problem. Pointing you in the right direction to why your car isn’t starting in the cold.
If you are facing difficulties with your car not starting in the cold or want to avoid it happening on a cold morning when you need to get to work, get in touch with our team. We offer complete winter checks to ensure that your car will be able to cope with the low winter temperatures.
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