How to Start a Diesel Engine in Cold Weather [8 Tips and Tricks]

Learning how to start a diesel engine in cold weather will keep your car or truck running in those frigid winter months.

If you think your diesel engine can handle the cold weather, think again. It’s five times harder to start a diesel engine at 0°F (-17°C) than it is to start one at 80°F (26°C).

There are two concerns to keep in mind when starting your engine in freezing temperatures: your fuel could gel, or the engine may not start due to electrical failure. You wouldn’t want either, as there is nothing worse than trying to start your day in cold weather only to realize your truck won’t start.

So, how does one get a diesel engine through the winter? We’ve prepared a comprehensive list of maintenance tips and tricks that you can use to avoid getting stranded in the cold.

How to Start a Cold Diesel Engine in Winter

You don’t want to get caught off guard when the temperature suddenly drops below zero, so it’s best to prep your vehicle for the cold as early as possible.

Crossing everything off your list can take anywhere from a few days to a few weeks depending on your schedule. The key is to get a head start on winter by completing these essential tasks:

1. Storing Your Vehicle

Of course, if you want to maintain the optimal temperature level for your diesel engine, you’d want to keep it out of the cold as much as possible. Even a few degrees increase in warmth can make the difference between your vehicle starting or not starting.

Avoid leaving your vehicle outside or in cold spaces for long periods. Insulate the vehicle as much as possible by wrapping it in an insulating cover.

See: The 10 Best Car Covers For Cars and Trucks

You might need to spend more money heating your garage, but your car or truck will thank you.

2. Use a Block Heater

If you don’t feel like heating your entire garage or can’t afford to do so, consider installing an electric block heater or battery tender to keep these internal components warm when the vehicle is not in use.

A heating element is highly effective at starting cold diesel engines in most cases.

If electricity is hard to come by where you are, use a diesel-fired coolant heater instead. It circulates the coolant over a heater to increase the temperature of the air-fuel mixture.

3. Replace Your Glow Plugs

Unlike gasoline engines, diesel engines don’t have spark plugs, as they don’t need them to operate. The closest thing they have to such a device are glow plugs, which are their first line of defense against the cold.

These small but powerful devices heat incoming fuel and air before they pass into the combustion chamber, ensuring that the engine gets hot enough to generate power on a cold day.

Your glow plugs don’t get much attention during the hottest months of the year, so make sure you either replace your glow plugs or check to see if they are up for another winter before it starts to turn cold.

If your engine is having trouble getting started in the cold, this might resolve the issue.

4. Install a Second Battery

Your glow plugs will only work if they have enough electricity from the battery. Unfortunately, vehicle batteries deplete very quickly in cold weather — dropping as much as 50% at -22°F (-30°C)!

Make sure your battery is fully charged before starting up or install a second battery just to power the glow plugs.

See: The Best Places To Buy A Car Battery

Just keep in mind that if your glow plugs don’t function properly, your vehicle will have difficulty starting in the cold or fail to start outright.

5. Change the Oil Regularly

Oil is the lifeblood that keeps an engine running, but the cold can cause your motor oil to gel up. Not only must you keep your oil tank full, but you must also change the oil often to avoid gelling.

Read: 5w30 Vs 10w30 [Which Oil Is Better?]

If the oil can’t circulate through the entire engine, you risk damaging some of the most crucial components of your engine. For instance, if you have an engine with a variable geometric turbocharger, you could damage the sliding sleeve that adjusts exhaust gas pressure, especially on the 6.0L engine.

 Find replacement 6.0 VGT actuators online to fix the issue.

6. Protect Your Fuel

Once your vehicle is ready for the cold, it’s time to turn your attention to the fuel itself. Diesel fuel can freeze just like other fluids.

Keep your gas tank full to avoid sudden changes in temperature and condensation. Use whatever fuel the manufacturer recommends for cold weather, which is usually Diesel #1 rather than Diesel #2, the primary choice for warmer weather.

Diesel #1 contains less cetane than regular diesel fuel. Moreover, it’s thinner to reduce gelling and more chemically unstable to make it easier to ignite.

Do your best to keep your fuel in a warm location to avoid freezing and use diesel fuel additives to reduce gelling.

Find a product that demulsifies water through the water separator to insulate your fuel from the cold. If appropriate for your fuel, mix the additive right after you finish refueling so that it can blend with the fuel.

7. Adjust Your Driving Habits

Now that you’ve taken all the necessary precautions to protect your engine from the cold, remember to adjust your driving habits. The worst thing you can do is hit the gas immediately after starting the engine.

Let the engine warm up by letting it idle for at least five minutes. This gives the oil a chance to circulate throughout the engine for more lubrication.

8. Watch for Warning Signs

Watch out for warning signs that something is wrong with the engine. If you experience a rough start or hard start, don’t assume it’s just the cold weather. It could be a sign that you need additional repairs. 

You can always find replacement parts for your diesel fuel systems online to fix the issue as soon as possible.

Final Thoughts

If you live in an area with cold winters and intend to use your vehicle throughout the season, learning how to start a cold diesel engine is essential. The last thing you want is to jump behind the wheel only to find that it won’t start.

What you must do is keep the engine in optimal running condition, which although requiring some work, can be done by just about anyone without the help of a professional.

As discussed in this guide, you need to ensure the vehicle is warm, and your best bet is to keep it out of the cold and use heating units such as a block heater and/or a diesel-fired coolant heater.

You must also make sure that your glow plugs are in good condition and have sufficient battery power. Consider connecting them to a secondary battery unit for extra peace of mind.

Change the engine’s oil regularly so that it doesn’t gel and protect the fuel by using the right type and ensuring the tank is full. If appropriate, use additives.

It goes without saying that you should, adjust your driving habits to match the drop in temperature. Before stepping on the gas and heading out, let the engine idle for at least five minutes to warm and loosen up its components.

Finally, watch out for signs that something is wrong with the engine, and address any problem quickly before it causes serious damage.

Now that you know how to start a diesel engine in cold weather, or, more specifically, how to maintain one, you might also be interested in learning how to gravity bleed brakes, how to start a car with a bad starter, and how to fix a sagging car headliner.