Diesel Engines: Maintenance of diesel engines

Maintenance of diesel engines

Diesel engines have a reputation for lasting years if well-maintained. Getting that long lifespan out of a diesel engine requires maintenance, and that means regularly servicing the hardware; replacing engine fluids and diesel engine oils that keep the engine lubricated and cool, as well as using high-performance fuels.

What else can we help with

  ✔ Crown HVO Fuel

  ✔ Carbon Offset Fuels

  ✔ Bulk DERV Fuel

  ✔ Industrial Heating Oil

  ✔ Red Diesel

  ✔ Home Heating Oil

  ✔ Kerosene

  ✔ Lubricants

  ✔ Ancillary Products

  ✔ Biodiesel

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Diesel Engines: Diesel furnaces and boilers

Diesel furnaces and boilers

The mechanics of boilers that run on diesel fuel (gas oil or commercial heating oil) is different to diesel engines – the fuel is atomised under pressure and a spark combusts the fuel. The combusted fuel heats water in pipes, and from there the heated water travels through the central heating system, keeping properties warm and providing hot tap water.

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Diesel Engines: Diesel power generators

Diesel power generators

For power generators that run on gas oil, the engine is similar to that of an automobile, with the key difference that the engine is connected to an alternator, which generates electricity. 

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Diesel Engines: Selective Catalytic Reduction (SCR)

Selective Catalytic Reduction (SCR)

If you’re using a modern Euro 6 diesel engine, the exhaust fumes are then sent to the SCR system to remove harmful emissions with the use of diesel exhaust fluid (AUS 32, commonly called AdBlue).

In the SCR system, the SCR catalyst mixes exhaust fumes with AdBlue diesel engine fluid, resulting in the NOx particles being reduced to NH3 (ammonia) and water being expelled from the exhaust valve.

Because the exhaust fluid is added inside the diesel system, it is essential to use AdBlue that meets ISO 22241 specifications to avoid harming your engine with rogue particles. Crown Oil supplies AdBlue® across the UK for a wide range of customers.

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Diesel Engines: Emission reduction in diesel engines

Emission reduction in diesel engines

Since 2015, diesel engines must meet Euro 6 standards in order to ensure minimal impact on the environment. To do this, engines have several systems in place:

Exhaust gas recirculation (EGR)
The EGR system is in place to reduce pollutants, specifically NOx emissions, coming from the exhaust.

Diesel Oxidation Catalyst (DOC)
The DOC oxidises unburnt fuel to CO2. Because of this system, hydrocarbons present in fuels are prevented from being blown out of the exhaust.

Diesel Particulate Filter (DPF)
The Diesel Particulate Filter works to reduce particulates (smoke) from the exhaust fumes, making sure the exhaust gases are clean and have as minimal impact on the environment as the Euro 6 standards can allow.

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Diesel Engines: Diesel engine system

Diesel engine system

While there are many applications for diesel engines, the system is broadly the same, since the majority are four-stroke engines. That means power is harnessed in four steps (stroke cycles), which we go through below.

Before anything happens in the engine, fuel is pumped from the tank to the engine. The fuel passes through the fuel filter which removes any particles that could damage the engine or block the fuel injector nozzles – such as diesel bug, dirt, or in cold conditions, waxed FAME biodiesel which causes many problems in cold winter, to the point where the 7% biodiesel content in red diesel used in agriculture is sometimes reduced by refineries to assist farmers

Stroke 1 – Intake stroke

The appropriate amount of fuel is brought in through the fuel injection system and mixed with air in the pistons, where they become compressed.

Stroke 2 – Compression stroke

The intake valve closes and compression begins resulting in compressed air and fuel

Stroke 3 – Combustion stroke

Fuel, air under intense pressure combusts, releasing fumes of ignited diesel.

Stroke 4 – Exhaust stroke

Spent combustion gases are forced out of the exhaust valves, through the exhaust manifold, and into the turbine (exhaust) side of the turbocharger.

Turbocharger

After the exhaust stroke, any remaining fuel fumes are sent through to the turbocharger. The turbocharger pressurises air into the cylinder which increases the oxygen content, resulting in a better burn. In fact, the turbocharging process can increase the power of a diesel vehicle by 50% while reducing the engine’s fuel consumption by around 25%.

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Diesel Engines: Fuels that can be used in diesel engines

The diesel engine in its many forms is the workhorse of modern industry. Our fuel experts explain what makes this type of engine so important

Fuels that can be used in diesel engines

For this reason, there are different types of diesel fuels that are authorised to be used in a diesel engine.

  ✔ Passenger vehicles

  ✔ Petroleum diesel (DERV or red diesel (gas oil))

  ✔ Paraffinic diesel (such as HVO fuel or GTL fuel)

  ✔ Biodiesel

Each type of fuel is produced to meet specifications that are intended for that kind of fuel. We have a dedicated specifications explainer that will explain these three fuels for diesel engines in closer detail.

What makes a diesel engine fuel?
What makes a diesel engine fuel?

The core property that fuels must have if they are to be used in a diesel engine is a specific cetane number. The cetane number quantifies out of 100 for how easily the oil combusts under pressure (the higher, the easier).

Mineral-based diesel has a cetane number of about 40, while higher performance alternatives such as HVO fuel or GTL fuel have a cetane score of 70 or greater, the higher cetane number results in improved burning – a fuel that more readily combusts and more complete burning, which itself provides cleaner emissions.

To be used in a diesel engine, fuels need to have an appropriate density and viscosity. For petroleum diesel fuel, this is between 0.82 – 0.835g/ml and its viscosity is between 2.0 and 4.5. Clean-burning alternatives need a similar density to diesel, however up to a 5.0 viscosity is required for paraffinic diesel fuels to ensure they meet the required regulations.

The fuel of choice for a diesel engine is based on what the engine will be used for. While most diesel engines are designed to run on middle distillate petroleum fuel, larger, more heavy-duty engines will be designed for use with heavier diesel fuel.

What about homemade biodiesel fuel?

There are some unofficial ways of powering diesel engines, such as mixing store-bought vegetable oil with reactants to create homemade biodiesel in order to save on fuel at fuel stations. While duty needs to be paid on an annual production of 2,500 litres and higher, if done at home, this fuel is produced entirely at your own risk.

Your vehicle’s warranty will likely not cover homemade fuel, and if poorly produced, it may result in damage to your engine, or worse yet, damage to your own and nearby property.

If your aim is to help the environment, you’re best off purchasing renewable fuels from specialist suppliers.

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