Do Modern Diesel Engines Need To Warm Up? [Past & Present]

Diesel engines are used in various industrial applications, finding their way to automobiles.

With that being said, there have been evident innovations in this technology throughout the decades, updating old systems for exceptional quality appropriate for today.  

Warming up diesel engines before driving was a system used in automobiles. But does it still hold today? 

Modern diesel engines start in cold weather with very little effort. But, just like people before going on extreme exercises, we still advise you to always warm up your diesel vehicle because they need higher temperatures for the engine to run effectively and it takes a longer time for the engine oil to circulate. 

Old vs. Modern Diesel Engines

YouTube video

The video explains how to differentiate between an old and a new diesel engine. It discusses how the manufacturing year of your engine influences whether or not you should warm up your engine before driving off.

Below is a comprehensive guide between an old and new diesel engine.

Carburetors on Old Diesel Engines

Cars back then used carburetors, which included a component known as a choke. People used to pull on the chokes to get their cars to idle and start warming up. Carbureted cars need to warm up because they can poorly run if they don’t.

Today, people still warm up their cars before driving, even in modern cars, because the practice was required for older engines. Up to this day, that practice has been carried on.

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Modern Diesel Engines

Cars nowadays don’t use carburetors and can start and run smoothly without a lengthy warm-up period.

Even in cold weather, a modern car does not need to be warmed up unless you drive around in places where the temperature is below freezing. 

Should You Warm Up A Diesel Engine?

YouTube video

The video starts off with the person clarifying that there is a lot of subjectivity when it comes to warming up your vehicle.

Also, there is no clear-cut way on how long you should warm up your vehicle. With that being said, you do not want to accelerate immediately, especially if you live in cold places such as North Dakota.

Give it a minute before you raise the RPM. What this does is that it lets your thick cold oil warm up to reach the places, nooks, and crannies inside your engine. Afterward, let your oil pressure and oil feed all the moving components.

At that point, if it’s cold outside, you can now rev up your engine to about 1000 RPM. This helps increase cylinder pressure, exhaust, and combustion temperatures.

The important takeaway in the video is that you have to get your oil and coolant temperatures on or above normal operating conditions in order to avoid wearing the engine.

There are some ways how to speed up this process using specialized equipment, such as:

  • Oil heaters
  • Block heaters

These may help your temperatures rise faster when you are warming up your diesel engine normally.

You should avoid idling your vehicle after you have warmed it up to avoid engine wear. Also, you might need to redo the whole process again if you idle it for too long.

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If you really need to do so, it is recommended that you rev up your engine to about 1000 RPM or higher to keep your cylinders from wearing out.

Frequently Asked Questions

Do I need an engine block heater?

In some cases, yes. It is good to plug in your diesel engine’s block heater, especially if you live in a cold climate.

Even when modern diesel engines use modern oils, cold temperatures can cause the oil’s viscosity and require time to warm up. 

When you use a block heater, you warm up your car when it is not used. This way, you can start driving your car without waiting for it to warm up.

A block heater isn’t really necessary in warm places like California or Florida because the weather is already warm.

If you prefer not to use an engine block heater, you can use diesel additives like kerosene to reduce viscosity even at low temperatures.

How long should I let my car idle?

If you have a carbureted engine, you only need 30 seconds of idling time, whether your engine is cold or not.

Idling your car is no longer necessary for modern engines. However, if you still want to do so, allowing your car to idle for about 30 seconds is sufficient to get things started. 

Is idling bad for my car’s engine?

In older car models, it is not bad to idle. It is safer to let them idle and warm up before hitting the road.

However, when it comes to modern cars, you should not let them idle because it is harmful to your engine and has a negative environmental impact.

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Idling is fine once in a while, but doing so too frequently can waste fuel. When stuck in traffic or waiting for someone to run to the store, it is best to turn off your car instead.

Is it necessary to warm up a modern diesel engine?

Unlike older models, you don’t need to warm up your modern diesel engine because they are designed to warm up as soon as you start them.

However, you should not rev up your car immediately until it has reached its normal operating temperature.

For other people, it’s a common practice for them to warm up their car before they can start driving. When you warm up your car, you let the oil circulate your engine, allowing it to lubricate moving parts before you can start driving. 

However, you no longer need to worry about warming up your engine to thaw gelled oil in modern vehicles. Modern automobiles use very light oils that flow immediately after starting the engine.

Idling can increase overall engine wear by causing the vehicle to run for longer than necessary. Besides, modern engines can warm up faster when driven than left idle.

Should I run it at full load to warm it up quicker?

The answer is no. You have to remember that your oil temperatures are still fairly low, which means that they are still somewhat thick.

Also, you want more smooth and free-flowing oil to go around your engine so that no mishaps and blockages happen.

Generally, the warm-up phase of the engine is the hardest on your vehicle. It could lead to fuel delusion, which means that some of your fuel has reached the oil.

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This typically happens to cars that are idle for too long in cold weather.

Remember to not go full load until your coolant temperature is around 180 degrees. Your engine parts are generally going to be cast iron, and you do not want them to be under a lot of pressure if they are cold. After that, you are ready to go full throttle when driving the vehicle. 

Should I warm up my vehicle even if it is not cold?

Yes, you could. Warming up before you drive has always been a sign of a good driver as it could help prevent your engine from slightly wearing when exposed to full loads immediately.

Does the amount of fuel affect the warm-up?

Condensation in the fuel tank might happen if they are not full. If it condensates inside yours, you might get frozen or gel-like fuel, and this would cause problems when starting up. Using fuel additives might lessen the condensation in your tank.

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