by Jeff Day
Cars have a least three good reasons for not starting, but more on that later. For now, let's just say that it's the coldest day of the year and your car has spent the night in the driveway. You're behind the wheel, keys in hand, hoping that — whatever those three reasons are — the car isn't about to remember one of them. And you wonder: What's the best way to start a car in cold weather?
Here's what car manufacturers advise:
- Turn the key to the position just before the one that starts the engine.
- Turn off the radio, the heater fan, the heated seats, the windshield wipers and rear defroster — anything that draws power. You want all the power going to the starter.
- Take your foot off the accelerator.
- Turn the key and release it as soon as the engine starts cranking. Cranking for too long drains the battery and can damage the starter.
- Once the engine is running, modern technology lets you drive the car without a warm-up period. Just drive gently for the first few minutes.
If the engine doesn't start, it's possible that you have flooded it — there is too little air and too much gas in the engine for the gas to ignite as it should. To start a flooded engine, push the accelerator pedal all the way to the floor. Keep it there, turn the key to the start position and hold it there while you count off three seconds. Hopefully, the car will start. If it starts and runs for just a bit before stalling, repeat the process, holding the accelerator down and turning the key for about 5 seconds.
If the engine doesn't turn over at any point in the process, the battery may be dead — even if it worked fine yesterday, when the weather was warmer. Cold weather slows down the chemical reaction in the battery, robbing it of its strength. Get out the jumper cables and see Jump-start a car for directions on starting a car with a dead battery. If the car still won't start after jumping it, call a mechanic. You've done all you can.
Three Reasons a Car Won't Start
- The vast majority of the time, a car that won't start has a dead battery. Have a mechanic test it after a cold-weather jump-start and replace the battery as necessary. Better yet, have your mechanic test it before the weather gets cold. If the battery needs replacement, you can have the mechanic do it or do it yourself. See Replace a car battery for step-by-step instructions.
- The second reason a car won't start could be that it needs a tune-up. In a car that is out-of-tune, the spark plugs fire at the wrong instant and the engine doesn't develop the power it needs to overcome the cold weather. Fortunately, most newer cars don't need a tune-up until you've put 100,000 miles on them, but check your owner's manual. Get the car tuned up as needed, preferably before the weather turns cold.
- The third reason: Sometimes the cold makes the oil so thick that the car has a hard time turning over — a problem made worse by using the wrong grade of oil or by having dirty oil. If the battery is good, the car is in tune and the car won't start without jumping, suspect an oil problem and have the oil changed. Check your owner's manual for the proper grade and to see whether the manufacturer recommends thinner oil in your climate. You can avoid oil problems by changing the oil in the fall.
If the climate is extremely cold, car owners often have block heaters in their cars. The heater connects to an outlet in the wall, and keeps the engine block; the oil and the radiator coolant warm enough for an easy start.
You can buy a car with a factory-equipped heater or have a mechanic install one for you. Some manufacturers recommend that, under certain conditions, you have a coolant heater to keep the radiator fluid from freezing. You may also want a separate oil pan heater to keep the oil warm and fluid. Check the owner's manual and ask your mechanic for advice.
Jeff Day grew up in Michigan where he learned most of what there is to know about cold weather.