Diesel engines are the powerhouses behind various industries, offering robust performance and unmatched efficiency. However, diesel engine runaway is an incredibly dangerous risk that all diesel engines face when working in the energy sector. In this blog post we will cover the intricacies of diesel engine runaway and explore what causes a diesel engine to runaway, how to stop it when it’s happening, and, most importantly, how to prevent diesel engine runaway from occurring at all.

What is Diesel Engine Runaway

Diesel engine runaway is what happens when your diesel engine starts taking in external gases from the air, causing the diesel engine speed to exceed the red line. Your diesel engine is running away when it gets to the point where the engine is running uncontrollably and you are no longer able to shut the engine down with the key. This is because the engine is taking in fuel from the air and doesn’t require the diesel fuel to continue running. Diesel engine runaway is incredibly dangerous and can cause significant damage to property, the equipment itself, and lead to injuries and death of your team. 

An oversped engine will destroy your engine, and the moving parts, if the engine isn’t shut down, can become red hot. When this happens, there is the capacity for sparks and contact ignition which will ignite the very same gases in the air, causing a catastrophic explosion. Diesel engine runaway can happen to any kind of equipment; however, it is found primarily in industrial settings where there is a larger risk of dangerous, flammable gases in the air.

What are the Consequences of Diesel Engine Runaway?

1. Safety Risks:


      • Risk of Explosion: The elevated temperatures and pressures associated with a diesel engine runaway pose a risk of explosion, especially if fuel or oil leaks occur and come into contact with hot surfaces.

      • Projectile Hazards: Engine components subjected to high stress during a runaway may disintegrate, posing a risk of flying debris and potential injury to nearby individuals.

      • Fire Hazard: The combination of uncontrolled combustion, fuel leaks, and high temperatures increases the likelihood of a fire, creating a significant safety hazard.

    2. Engine Damage:


        • Overheating: Runaway situations often result in excessive heat generation due to uncontrolled combustion, causing damage to engine components and compromising its overall structural integrity.

        • Mechanical Stress: The engine is not designed to operate at the extremely high RPMs reached during a runaway. This can subject various components, such as pistons, crankshafts, and bearings, to excessive mechanical stress, leading to accelerated wear and potential failure.

        • Oil Contamination: Uncontrolled combustion can cause oil contamination with fuel, leading to a breakdown of lubricating properties and increased friction within the engine.

      3. Environmental Impact:


          • Air Pollution: The uncontrolled burning of fuel in a runaway situation can result in the release of pollutants into the air, contributing to air pollution.

          • Oil Spillage: If a runaway leads to engine damage and oil leakage, it poses a risk of environmental contamination, especially if the spill reaches soil or water bodies.

        4. Financial Consequences:


            • Repair and Replacement Costs: Repairing or replacing a diesel engine that has experienced runaway can be expensive. In addition to the engine itself, peripheral systems and damaged equipment may also require repair or replacement.

            • Operational Downtime: A runaway incident can result in extended downtime for the affected equipment, impacting productivity and potentially causing financial losses.

          What Causes Diesel Engine Runaway

          There are many causes that can lead to diesel engine runaway. By understanding the root causes of diesel engine runaway, we can develop plans for effective prevention. Common causes of diesel engine runaway include:


              • Oil leakage

              • Air contamination

              • Faulty turbochargers

              • Worn piston rings

            Oil Leakage: Diesel engines rely on a precise balance of fuel and air. When oil leaks into the combustion chamber, it acts as an additional fuel source, leading to uncontrolled acceleration.

            Air contamination: If your engine is running in an area with contaminated air, the engine’s air intake supply is compromised, causing it to bring in gases that can lead to diesel engine runaway incidents.

            Worn Piston Rings: Aged or damaged piston rings can allow oil to seep into the combustion chamber, exacerbating the risk of diesel engine runaway.

            How to Stop a Diesel Engine Runaway

            If your diesel engine starts running away, it can be normal to feel a sense of dread or panic. However, the most important thing to do if your diesel engine starts running away is to remember your safety training. Here are some things you can do if your diesel engine starts running away.

            Cut Off the Air Supply

            Immediately restrict the engine’s air supply by closing the air intake shut-off valve. This helps limit the combustion process. If you have an automatic shut off valve, this is done automatically once the diesel’s RPM exceeds a safe limit. However, if you have a manual positive air shut off valve or no positive air shut off valve at all, you’ll have to see if there is a switch to shut the air supply. 

            Turn Off Fuel Supply

            Shut off the fuel supply by either turning off the engine or utilizing an emergency fuel cut-off system. If you can catch the diesel engine runaway before it becomes uncontrollable, you may be able to turn off the fuel supply and shut the engine down. If the engine is running away and taking in fuel from the external air, the only way to stop the diesel engine from running away is to shut off the air intake system.

            Use a Fire Extinguisher

            Although a fire extinguisher into the intake system can cause some damage to your engine, a CO2 extinguisher will stop the engine from burning fuel and at least avoid the risk of sparks and explosions.

            Clear the Area

            If you are unable to get your diesel engine under control once it starts to run away, it’s time to evacuate. This is critical, when your diesel engine starts to runaway you have seconds to get out of the danger zone. If you don’t have a positive air shut off system or way to stop your engine, evacuate immediately.

            Preventing Diesel Engine Runaway

            The only way to prevent diesel engine runaway safely is an emergency shutdown system. Without emergency shutdown systems like a positive air shut off valve or a gas-detection shut off system, you always run the risk of diesel engine runaway.


            The ShockerPASS is an emergency shutdown system for diesel engines that will directly prevent diesel engine runaway. If you want to prevent diesel engine runaway, install our manual or automatic positive air shut off valve (ShockerPASS). The automatic shut off will immediately activate when your diesel engine’s RPM is too high, while the manual shut off will require an operator to flip the shut off switch to prevent diesel engine runaway. Both systems are incredibly effective and an important tool if you’re looking to stop diesel engine runaway and protect your people and property.


            The ShockerEDGE is an emergency gas detection and shut down system. The ShockerEDGE will prevent diesel engine runaway by immediately shutting down your engine if it detects high levels of dangerous gases in the air. This means that your engine will shut down before it even starts to runaway. The ShockerEDGE turns your engine into a continuous air monitor, so as you are running your engine your gas detector is automatically recalibrating and pulling in air to test for contamination. If you are looking for a state of the art piece of technology to keep your people safe and prevent diesel engine runaway, install our ShockerEDGE!

            Prevent Catastrophic Diesel Engine Runaway

            Diesel engine runaway is a serious concern that demands proactive measures and a comprehensive approach to prevention. By understanding the causes and implementing effective preventive strategies, you can safeguard your diesel engine and those around it from potential catastrophe. Install an emergency shutdown system in your diesel engine to ensure that you never have to deal with the dangers of diesel engine runaway.

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