Cars and cold weather
by Jim Kerr

The coldest days of winter are tough on vehicles. Batteries lose their cranking power, charging systems are overworked, and every part is stiff to move. This is a time when parts break and severe wear occurs, but there are things we can do to reduce the damage. Let's look at what happens when that cold vehicle is started.

Getting into that frozen block of metal we call a vehicle is only the first challenge. Then comes the chore of starting it. Starting fuel injected engines is much different compared to older carburetor-equipped vehicles. Don't touch the throttle - just turn the key until it starts. Older throttle body injected engines may start faster if the throttle is opened slightly to allow fuel past the throttle plates, but leave the throttle closed on port injected engines. Not sure what you have? Almost all newer vehicles use port injection systems because of the better fuel economy and lower emissions, but any repair shop will be able to tell you what system is on your vehicle.

If you smell gas while trying to start the vehicle and the engine has been cranking far too long, then the engine may be flooded. This means that there is too much gasoline in the cylinders and the spark plugs are wet, causing the spark to go across the insulator instead of across the electrodes. Putting the gas pedal to the floor during cranking will turn off most fuel injection so that the flooded engine can be "cleared", but the engine may still not start unless it is warmed up and the spark plugs are changed.

Manufacturers recommend spark plug change intervals anywhere from 80,000 km to as high as 196,000 km, depending on the model of vehicle. Unfortunately, when an engine is flooded, the spark plugs start misfiring across their insulators and it is difficult to make them work properly again. I have worked on new vehicles that needed new sparkplugs after the engine was flooded. In the past, technicians used to clean sparkplugs with abrasive powder or heat them with a torch to burn off the carbon, but this doesn't work anymore. Replacing flooded sparkplugs may be the only cure for future hard starting, rough running, and poor fuel economy. Many new types of sparkplugs are expensive, so we need to try to prevent flooding the engine.

Keeping the battery and engine warm will allow the engine to crank and start faster, and prevent flooding. Electric battery blankets keep a battery warm. So will a small trickle charger. A battery sitting at minus 20 degrees has half of the power of a similar battery when it is warm, so if you want the engine to start, keep the battery warm.

Keeping the engine warm by using a block heater also helps starting, but another major benefit is reduced engine wear. Warm parts allow engine oil to flow easier into critical areas. Most engine wear occurs in the first couple minutes after a cold start. Rich fuel mixtures wash lubrication from the cylinder walls. Thick oil doesn't spray onto moving parts as easily, so using a winter grade oil will help reduce engine wear.

When the engine is first started, the oil pump forces oil into the oil passages and through the oil filter. The pleated filter element may restrict thick oil too much, so a bypass valve is designed into either the oil filter or the engine itself so the thick oil can bypass the filter. Oil may bypass the filter for only a few seconds or for nearly a minute if temperatures are cold and the oil viscosity is high. During this time, unfiltered oil flows to the engine, which is better than no oil, but it still allows dirt particles to flow to moving parts. Changing to a winter grade oil with lower viscosity helps keep bypass times short and provides faster lubrication to moving parts. Owner's manuals list oil viscosity best suited for cold winter driving.

Vehicles subjected to cold winter starts experience more engine wear in a couple years than a California vehicle may in a couple decades of starts. Fuel injection has helped, but we can also do things to reduce engine wear. Use the right oil, plug in block heaters before cold starts, and drive with a light throttle until the oil is warm and lubricating well.