As cities tend to become more and more populated, the problem of transport becomes more and more complicated. Endless traffic jams, with numerous cars pointlessly idling while unnecessarily burning excess amounts of fuel. Also, some drivers still think that it is good to “warm up the engine” before driving. That draws an important question – is it better to leave the diesel engine running?
The short and simple answer is no; leaving the diesel engine running is not better. There is an old myth that when you start the engine, either a diesel or a gasoline one, it is to let it warm up. That theory doesn’t hold up. The best way to warm up the engine is by driving it casually for a few minutes. It will warm up the cold diesel engine much better than pointless idling.
It will not only not warm up the engine properly, but it will also shorten its life. There are also the issues of fuel consumption and environmental impact. The engine will waste a lot of fuel and produce unnecessary harmful emissions. Stay with us and learn the potential damage of engine idling and what are the consequences of it.
What is a Diesel Engine?
A diesel engine is an internal-combustion engine also known as a compression-ignition engine. The pistons of the engine compress the mixture of air and fuel. When the ratio between air and fuel is around 15 to 1 the mixture explodes. That explosion is forcing a piston back with the use of a reciprocating motion. The crankshaft then converts it into rotary motion. That motion is moving the car.
Impact of Continuous Running on Diesel Engines
There are several negative sides to leaving your diesel engine running idle. The most serious issues are shortened engine life, fuel consumption, and environmental impact.
Yes, there are some pluses, but they are focused on the commodity of the drive. With the engine running, you can keep an ideal cabin temperature. The engine temperature will not fall, but vehicle performance will not be at ideal levels. All in all, it is not very beneficial to keep your engine running on idle.
Engine Wear and Tear
Running a diesel engine at low speed or on idle will cause long-term damage to the engine components twice as fast as a regular drive. When the engine is not at full operating temperature, the fuel is not combusting completely. That creates carbon deposits creating problems for the exhaust system. Proper combustion temperature minimizes this problem.
Poor combustion also leads to a buildup of unburned fuel residue, which clogs the piston rings. This results in worsened sealing efficiency. When the hot combustion gases pass poorly sealed piston rings, they cause lubrication of the oil on the cylinder walls. That thin glaze erases the pattern of honing marks placed on the bores. Those marks return the oil to the crankcase through the scrapper ring.
Fuel Consumption Analysis
Depending on the engine in question, it can consume between half and one gallon of diesel for an hour of idling. That will not only take a hefty sum from your pocket, but you will negatively impact the environment. It is a proven fact that idling for more than 130 seconds wastes more fuel than turning your engine off and on.
Lifespan Implications
One hour of engine idle is comparable to 80 or even 120 minutes of regular driving. That means when you idle you are shortening the life of the engine over time, sometimes at a double speed. You are not saving, or warming up your engine, you are destroying it. The only time the engine pre-heating can extend the engine life is in very cold weather.
Check Out Is Idling Your Engine Bad? Does Idling Hurt Your Engine?:
Contrasting Diesel Engines with Gasoline Engines
Gasoline and diesel engines are the most commonly used internal combustion engines. They have different start-up temperatures and different temperature ranges. They offer different engine performance and have their unique characteristics.
Differences in Operation
Both diesel and gas-powered engines work on internal combustion principles. The difference is that gasoline engines use spark plugs to ignite fuel. In gasoline-powered engines, the fuel is injected into the combustion chamber, where it is mixed with air. This mix is ignited with a spark plug.
In diesel engines, the pistons are compressing the air and thus increase the temperature in the cylinder. Then the atomized fuel is injected into the cylinder when it ignites. The energy from the ignition moves the piston down and transfers the energy to the crankshaft. From there, it is moved to the powertrain.
Comparative Idle Times
The gasoline engine usually idles at between 600 and 800 RPM. The diesel, on the other hand, idles between 650 and 750 RPM.
Did You Know: Both for diesel and gasoline engines, long idle times are not recommended. They have several same engine components that will fail faster if the idling is frequent.
Scenarios of Diesel Engines Running Continuously
There are cases where engines have to work constantly. These engines are used in long-haul trucks, stationary machinery, and in diesel generators. Newer types of these engines have electronic engine controls that help in running them in long intervals.
Long Haul Trucks
One of the rare cases when it is better to keep the engine running is in long-haul trucks. Some of these trucks have installed refrigerators to keep the cargo cold. These refrigerators cannot work with a turned-off engine. Most of these trucks have long-distance destinations to cover, and drivers often sleep in them. A running engine also keeps the HVAC system running while the truck driver sleeps.
Also, constructing these engines allows and advises to keep them on as long as needed. Turning on and off these engines is causing more problems than constant running.
Stationary Machinery
Stationary machinery uses stationary engines that are constantly working. These engines found their use in power plants, oil rigs, large manufacturing plants, and water pumps. They are primarily powering equipment that needs to work all the time. Turning off the water pump or a power generator in a plant could result in excessive damage.
Diesel Generator Usage
Diesel-powered generators are mostly used as a backup source of power. They are always on standby, waiting to jump in and replace the primary power source. They can be used in homes, all sorts of plants, but also for off-grid living.
This type of diesel engine has this working principle:
- The air is supplied to the generator until it is compressed. Then the diesel is injected.
- The mix of compressed air and diesel fuel creates combustion thus starting the generator
- The heat created in the engine is converted to mechanical energy. It then enters the alternator and converts the energy into electricity
With proper maintenance and fuel supply, generators can work constantly for a very long time.
Financial Implications of Leaving a Diesel Engine Running
Running the engine on idle will produce two types of costs. The cost of used fuel and the maintenance costs. You can turn the engine off and save fuel and money. Also, you can turn the engine off and save the engine components. When the engine is running idle, the components will wear faster.
Cost of Continuous Running
The fuel price varies from time to time and from fuel to fuel. But, running an engine idle for more than 30 seconds results in more fuel burned than if you decide to turn the engine off and on. Every minute an average diesel engine uses 2.4 oz of fuel. Think about that when you are idling for a long time.
Potential Maintenance Expenses
Leaving the engine idling will result in shortening its life. Glazing and carbon buildup can happen, demands stripping down the engine and re-boring the cylinder bores. The price of this operation can go from $250 to more than $300, depending on the engine size and type. Sometimes the damage can be so extensive that the engine cannot be repaired.
Environmental Consequences of Leaving a Diesel Engine Running
Idling compromises a serious percentage of all bad emissions of the daily work of every engine.
- Emission Analysis
This analysis is taken from pickup trucks and heavier-duty diesel engines but is the data to make you think.
Of all daily emissions idling takes a serious share of all bad emissions:
- Hydrocarbon emission (HC) – 27%
- Nitrogen oxide emissions (NOx) – 7.4%
- Carbon dioxide emissions (CO) – 12.4%
- Particle pollution (PM) – 8%
- Direct fuel emission – 5.6%.
- Impact on Air Quality
All these excess damaging emissions result in a lowering of air quality. That results in the rise of pulmonary and respiratory diseases, especially in children. The rise of asthma and different allergies are evident.
Is it Bad to Leave Diesel Trucks Running?
It is bad because it creates bad emissions, it wastes fuel, and shortens engine life. Idling doesn’t offer many positives when compared to these major issues. Constant cabin temperature is a small benefit compared to all the problems that idling creates.
FAQs
Why do people leave diesel running?
The most common reasons for keeping the engine running are:
– Diesel can be stubborn and hard to start at low temperatures
– Idling is keeping the battery power always at maximum
– Keeping the ideal temperature of the engine and the cabin.
How long can a diesel engine run continuously?
It can work until it goes out of fuel. Although if the engine has overheating problems, it will shut off earlier.
What is the benefit of high idle on a diesel engine?
There are a couple of benefits of high idle, and the most obvious ones are:
– It prevents wet stacking. Wet stacking is when the cylinder temperature is not high enough to burn all the fuel
– Keeping the oil pressure high. This helps in properly lubricating the engine
– Reduce soot buildup. The soot buildup is created at low RPM. Higher idle prevents creating massive sooth buildup
– Helps in circulating oil and coolant. Before you turn off the engine after a long or difficult drive, keep the engine at high idle for a minute or two. That will cool down the turbo and other components.
Final Considerations
Combating the air pollution is in full swing. Cars today have developed new emission control systems. New types of fuels, like biodiesel, are made to lower pollution levels. Lowering idling pollution is a high priority. More and more cars have stop-and-go systems that automatically shut downs the engine when idling.
Drivers need to learn about the downsides of prolonged idling, like fuel consumption, wear and tear of the engine components, and bad emission. When you are parked for some time, and you will stay for some time, turn off the engine. Save the engine and the environment.
